Assessment of human and physical factors influencing spatial distribution of vegetation degradation - Environmental Protection Area Cachoeira
das Andorinhas, Brazil
Marise Barreiros Horta
March, 2002
Assessment of human and physical factors influencing spatial distribution of vegetation degradation - Environmental Protection Area Cachoeira das Andorinhas, Brazil
by
Marise Barreiros Horta
Thesis submitted to the International Institute for Aerospace Survey and Earth Sciences in partial fulfilment of the requirements for the degree of Master of Science in Natural Resources Management
Degree Assessment Board
Name Professor
Name Examiners
INTERNATIONAL INSTITUTE FOR GEO-INFORMATION SCIENCE AND EARTH OBSERVATION
ENSCHEDE, THE NETHERLANDS
Disclaimer
This document describes work undertaken as part of a programme of study at the International
Institute for Geo-Information Science and Earth Observation. All views and opinions expressed
therein remain the sole responsibility of the author, and do not necessarily represent those of
the institute.
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
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ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
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ACKNOWLEDGMENTS
I am very grateful to all the teachers and staff of ITC, for the patient and encouragement in the task of
introducing me in the world of pixels, and its amazing applications in ecological issues.
I would like also to express my gratitude to the Dutch Government and the Netherlands Fellowship Program (NFP) for providing me the opportunity to continue my studies. I extend my thanks to Roberto Cardoso, director of AMBIO Geology and Environmental Engineering Company in Brazil, for all the support.
I am very thankful that I had the generous and wise supervision of Dr. Wietske Bijker, through the journey of learning and growing during my research. Many thanks to Ir. Edwin Keizer for his excellent supervision, involvement, encouragement, suggestions, and pleasant friendship. Many special thanks to Prof.
Hans ter Steege that provided fundamental critical guidance in statistics.
Thank you Dr.Michael Weir, for the comprehension and help during the hard times. Thank you Dr.
Robert Albricht and Dr. Iris van Duren, for the openness and unconditional willingness to help. I appreciated that. Thank you Dr. Jan de Leew for the important critical advises during mid term evaluation. To the
Ilwiss expert …….. , thanks for the tips.
To my many colleagues in ITC: my love and gratitude. It was a pleasure to be part of this multicultural
environment. My special thanks to José Santos for the immeasurable help, support, care, present during
times of laughs, tears and fears. My friends Alejandra Fregoso and Valéria Gonçalves, you are in my
heart girls.
In Brazil there are several people and organisations that I would like to thanks, and without them this research would not be possible. I would like to thanks to Aristides Guimarães Neto from the State Forestry
Institute (IEF) for the logistics support, assistance in the field, suggestions and friendship. To the IEF, my
gratitude for the interest and support. Many thanks to fieldwork assistants: Paulo, Walmir and Jorge. My
deepest appreciation to all the team of Geoinformatics Division in FEAM (State Foundation for Environmental Control) for the provision of the Landsat TM image 2000 used during the research and many other
maps. My thanks to the directors Luiz Fernando Assis and Adriano Macedo. Special thanks to Regina
Camargos, Bernadete Barros and Ivana Lamas for inspiring me to take this challenge. Much gratitude to
you Polynice Rabello, for providing all the maps and sharing immeasurable helpful emails. My thanks
extend to IBAMA, CETEC and CPTEC for providing image and maps. From UFOP (Federal University
of Ouro Preto) I would like to thanks my friend and colleague Hildeberto Caldas and the herbarium cura-
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
tor Maria Cristina Messias. In São Bartolomeu my thanks to Ronald de Carvalho (Manuelzão Project) and
Mrs. Serma Fortes.
Finally, I am in debt with my mother, father, sister and brothers, for the loving support and encouragement. I extend my thanks to my family in New York (Brown family and Capoeiristas) for the support,
encouragement, care and love.
ABSTRACT
Most of the investigation of factors influencing vegetation degradation in the spatial context has been directed at arid landscapes or at degradation of temperate and tropical forests.
This study examined the influence of human and physical factors in the spatial distribution of vegetation
degradation in the Environmental Protection Area Cachoeira das Andorinhas (Brazil), characterized by
subtropical moderately humid climate. The degradation affects forest, savannah and rocky shrublands
formations.
Remote Sensing, Geographic Information Systems (GIS) and statistical analysis techniques were used
together with field data collection. Landsat TM image, topographic map, DEM and secondary data were
used for generation of maps of the human and physical factors examined. Those factors comprised: distance to the roads, distance to rural settlements/village/city, distance to tourist sites, distance to mining
sites, distance to agricultural areas, distance to the drainage, slope and geology. The diagnosis of vegetation degradation variations was made with utilization of five ecological indicators: invasive species cover,
understory cover, canopy cover, bare soil cover and dead shrub percentage. The total of 47 sample plots
was classified according to vegetation degradation variations. Principal Component Analysis was performed for generation of scores that represented numerically the levels of vegetation degradation. Regression analysis was used to investigate the relationship between vegetation degradation and human and
physical factors, and to select significant variables, used in the assessment of areas at risk of vegetation
degradation.
The factors slope and distance to tourist sites presented significantly negatively correlated to the vegetation degradation in forest and savannah /rocky shrublands formations, respectively. The assessment of
areas at risk of vegetation degradation was based on those factors that represented 20% and 19% respectively of the variability of the vegetation degradation variations in the area. The spatial variations of vegetation degradation were mapped for the extremely degraded forest areas (scrub).
The factors slope and distance to tourist sites can enhance accessibility of humans and livestock to natural
vegetation areas, which may increase intensity of damaging activities in areas of lower slope and shorter
distance to tourist sites. The low significance of the factors used to assess areas at risk of vegetation degradation suggested limitations for further use of the information. The possibility of mapping spatial distri4
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
bution of vegetation degradation only for extremely degraded areas suggested limitations of using remote
sensing techniques (Landsat TM imagery) to detect the degradation process when considering one snapshot in time, few undisturbed situations and lower levels of degradation.
The information can contribute to improvements in conservation management strategies in the protection
area, but the low influence of the factors in the overall vegetation degradation process has to be considered.
CHAPTER1. INTRODUCTION
1.1.
Introduction
Human induced chronic disturbance has been referred as one of the major causes of vegetation degradation in developing countries (Singh 1998). At the global level, socio-economic and political forces that
determine the mode of development in many developing countries play an important role in the processes
of vegetation degradation and destruction (Mather 1992). At the national and local levels, forest degradation has been suggested to be linked to rural population pressure, through subsistence farming, grazing,
and selective wood extraction, and as a result of large-scale development projects (World Resources Institute 1996).
Vegetation degradation is defined as the deterioration of the healthy conditions of the vegetation, expressed through changes in its composition, structure and function (Kakembo 2001;TCM 1998). The
global assessment of forest conditions comprehends some standard measurement, that include (World
Resources Institute 1996):
• the degree of degradation, or the extent of fragmentation and biomass removal
• the degree of naturalness, or the extent to which recent human activity has modified forest structure
and species composition
• the intensity of forest management
• the relative health of the tree species within a forest
Vegetation degradation, unlike deforestation, is not a very obvious phenomenon. The changes are revealed gradually, sometimes not in terms of decrease of area, but represented by qualitative losses, for
example, through the reduction of species diversity, increase of invasive species, decrease of the shrub
layer, reduction of woody species and biomass decline (TCM 1998, Hargyono 1993).
For that reason, the condition of the world’s forest and vegetation has not been assessed comprehensively
since degradation, naturalness, and health is difficult to quantify on a regional or global scale. Despite
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
that, forest degradation is a significant concern due to the substantial losses of biomass and habitat fragmentation, not reflected in deforestation estimates (World Resources Institute 1996).
Some authors investigated factors influencing vegetation degradation in the spatial and temporal context.
Kakembo (2001) investigated the trends in vegetation degradation in relation to land tenure, rainfall and
population changes in South Africa. The study revealed land tenure as the main controlling factor to the
spatial and temporal variations in vegetation degradation in the area. De Pietri (1995) examined the spatial configuration of vegetation as an indicator of landscape degradation due to livestock enterprises in
Argentina, and developed an index for detection of significant changes in the spatial configuration of
plant communities. De Hier and Hussin (1993) refined the Area Production Model (APM), originally developed by Nilsson in the early 1980s. The model makes use of the factors population growth, gross domestic product (GDP) and agriculture productivity to predict the amount of land that might be transferred
from forest and other land uses, to agriculture.
Mather (1992) emphasized the influence of some proximate factors in the processes of deforestation and
forest degradation: roads network, that increases accessibility, and slope steepness, found usually inversely related to the cited processes. According to the author, those factors represent a physical expression to some underlying structural driving forces, such as demographic and political factors.
Most of the vegetation degradation research has been directed at arid landscapes associated with land
degradation, desertification and soil erosion processes (Michael Bridges et al 2001, Guerrero-Campo &
Montserrat –Marti 2000, Kembron 2001), or at degradation of temperate and tropical forests (World Resource Institute 1996). Eswaran (2001) mentioned the need for establishment of distinct criteria for evaluating vegetation degradation. The author argued that the overlap between vegetation and land degradation
is associated to conceptual similarities, since both processes may imply on reduction of biomass, decrease
in species diversity, or decline in nutritional value for livestock and wildlife. The situation has generated
studies that combine vegetation degradation with other processes, such as, soil erosion. In general, however, they lack considerations of the quality and quantity of vegetation.
The present research, on the other hand, examines the vegetation degradation phenomenon in a protected
area, characterized by subtropical moderately humid climate, where degradation affects not only forest,
but also other vegetation types. It aims to investigate the influence of human (rural settlements, villages,
city, agricultural areas, tourist sites, mining sites, roads network) and physical factors (slope, geology,
drainage) in the spatial distribution of vegetation degradation, in the Environmental Protection Area
(EPA) Cachoeira das Andorinhas, Minas Gerais, Brazil. For that, Remote Sensing and Geographic Information Systems (GIS) techniques are used coupled with detailed field data collection. Therefore, it can
widen the perspective over the problem, and be a contribution to the understanding of the influence of
some spatially explicit factors, in the vegetation degradation process. Additionally, it can offer some insight into the situation of nature conservation in Brazil, especially regarding the EPAs that intend to harmonize land use development and biodiversity protection.
1.2.
Aspects of nature conservation and Environmental Protection Areas in
Brazil
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Nature conservation in Brazil has been taken into consideration since the 1930s with the first delimitation
of areas to be protected. Nevertheless, it was in the 1980s that the network of protected areas expanded.
Nowadays, the country has 785 conservation areas, corresponding to 69 174 600 ha or 8.13 % of the total
national territory, which are administrated and controlled by the IBAMA - Brazilian Institute for Environment and Renewable Natural Resources (MMA 1998; Camargos & Lana 1996).
The conservation areas belong to several management categories. These categories are divided in areas of
indirect and direct use, according to the level of restriction for the exploitation of natural resources. The
indirect use conservation areas comprise strict reserves, where the exploitation of natural resources is prohibited, and the principal objective is ecosystem preservation. Examples are the National Parks, Biological Reserves and Ecological Stations. The direct use areas are those where the exploitation of natural
resources are allowed, according to specific management plans and legislation. Examples are the National
Forests and Environmental Protection Areas (MMA 1998).
The Environmental Protection Areas (EPAs) corresponds to IUCN category V or “Protected Landscapes
and Seascapes” (IUCN 1992). They were created in the 1980s, as a result of the search for innovative
strategies that harmonize nature conservation and economic development, in areas of intensive population
pressure in Brazil. The general objectives of the EPAs are the biodiversity protection and the land use
development, in a sustainable perspective.
Currently, there are 38 EPAs in Minas Gerais state covering 1 352 031 ha, equivalent to 64% of the total
protected area and 2% of the total area of the state (Camargos 2001). The sites are selected, according to
the presence of remarkable natural and semi-natural characteristics, related to their biotic, abiotic, cultural
and aesthetic attributes (Camargos & Lana 1996).
The EPAs allows the maintenance of private ownership and economic activities compatible with the nature conservation, such as ecotourism and recreation. Some other activities are not allowed, such as industries, mining activities, abusive use of pesticides, predatory hunting, edification, construction, and others,
that contribute to erosion processes. Activities related to the road construction, urban projects, mining
activities and earthwork depend on licensing procedures, operated by the state or federal environmental
protection agencies (Minas Gerais 1989).
The planning framework for the EPAs includes a cluster of political and administrative activities, that
starting from the actual reality in the area, lead to a new scenario, where the use of natural resources is
oriented to the biodiversity protection and improvement of life quality of the local people involved. The
management plan generated comprehends the socio-environmental analysis, logical framework, action
plan and environmental zoning (Arruda 1999).
Despite of the importance of the creation of the EPAs, most of them exist only on paper and lack environmental functional zoning, land use and management plans for the true implementation of this conservation category.
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
1.3.
Vegetation degradation process in the Environmental Protection Area
Cachoeira das Andorinhas
A first concern that was raised during the present research was about what and in which extent major
variations in the vegetation conditions of the EPA Cachoeira das Andorinhas can be attributed to human
disturbance. This consideration was made because natural disturbance processes are a normal component
of vegetation ecosystems (Sprugel 1991) and affect community structure and dynamics (Pickett et al
1989; Harmon et al 1983). When it comes to a long-term time scale, it becomes patent that most of the
vegetation ecosystems have been shaped by interactions between human and natural disturbances
(Sprugel 1991). However, chronic human disturbances can lead to large alterations in the structure and
composition of vegetation, and establishment of degradation processes (Singh 1998). Those processes are
pronounced by inappropriate land-use practices, and increase in population pressure (Kakembo 2001).
Considering the reports of human activities in the EPA Cachoeira das Andorinhas (Andrade 2000) and
the findings of damaging activities signs in most of the areas investigated during the research, the human
activity was considered of great importance and major influence for the vegetation degradation conditions
evidenced.
Another relevant concern was from which point a vegetation ecosystem can be considered degraded and
what quantitative measurements could be used. Andreasen et al (2001) argued that a degraded condition
is the end of a continuum that comes from an “unimpacted state”, and defines the “socially unacceptable
state”. The author suggested that for definition of degraded and unimpacted conditions it is fundamental
the use of expert judgment, reconstruction from historical records, and selection of candidate metrics to
measure in the location under study. Those candidate metrics or ecological indicators are then used to
assess the conditions of the environment (Dale & Beyeler 2001).
The present study had the underlying orientation of the verification of occurrence of degradation processes in the different vegetation types of the EPA Cachoeira das Andorinhas and establishment of quantitative measurements of the vegetation conditions, through the use of ecological indicators.
1.4.
Problem statement
The understanding of the environmental conditions and factors involved in the deterioration of the ecosystems found inside protection areas are fundamental for appropriate management. Chronic disturbances
can lead to vegetation degradation and subsequent reduction of desirable characteristics of an area for
nature conservation.
Ferreira et al (1999) pointed out the relevance of studies of the situation and vulnerability of protected
areas in Brazil, since most of them have not been properly implemented. This is the case of the EPA Cachoeira das Andorinhas (located in Ouro Preto county) that lacks a proper management plan and in this
context, vegetation degradation is taking place. The protected area was created by the decree number
30264 on 16/10/1989, and since then, no effective intervention for biodiversity protection and land use
development has been undertaken.
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
The EPA was created in that site mainly for catchment protection, considering that one of the most important rivers in the state, Velhas river, has its origin in the Andorinhas waterfall and other springs inside the
area. Other characteristics taken into consideration were the relevant attributes concerning historical, cultural, landscape, and natural values. In addition, Ouro Preto is an important historical and tourist center,
and the development of ecotourism in the site was seen as an opportunity to extent the tourism network
(Minas Gerais 1989).
That region has a long history of human interventions in its natural ecosystems. Ouro Preto was capital of
the province in 1823, mostly due to the richness in gold. Until recently, the area was exploited by gold
mining companies. In the last past years, activities of forest cutting for charcoal production spread
through the region. Inside the EPA, siderurgic enterprises explored forest areas for charcoal production
and in many sites the forest has been regenerating for a short time (among 10 and 20 years). Forest destruction for charcoal production, is reported by researchers (Zurlo 1978) and dwellers of the village São
Bartolomeu. The activity was a source of income for many villagers that worked for the company Queiroz
Junior Siderurgic. The exploitation was interrupted since the site became a protection area. Nevertheless,
other damaging activities are still jeopardizing the natural vegetation in the EPA.
The influential factors for vegetation degradation in the EPA Cachoeira das Andorinhas can be distributed at different levels. They are summarized in the Figure 1. Considering a broader perspective, demographic, socio-economic and political factors are associated to population pressure, poor incentives for
development and inefficient strategies for the management of the area. The population pressure takes
place mainly in the Ouro Preto vicinity, which population has increased considerably in the last past years
(IBGE 1991, IBGE 2001 - Table 1). Activities of encroachment into the conservation area, illegal settlements, illegal mining and tourism pressure are taking place.
On the other hand, the lack of incentives for the small scale agriculture, lack of alternative activities and
restrictions for the exploitation of natural resources led part of the people that live inside the EPA, specially in the rural areas, to move to other sites, including Ouro Preto. The population has been decreasing
slightly in the last past years (IBGE 1991, IBGE 2001 –Table 1). The limited involvement and support to
the communities that remain inside the area has been contributing to the intensification of damaging activities, such as, free grazing, selective cutting, and mining. Those damaging activities are coupled with
the traditional use of fire, for agriculture improvement, contributing to vegetation degradation in the area.
Table 1: Demographic figures for Ouro Preto and São Batolomeu, in the years 1991 and 2000 –
Source IBGE
City - Village
Ouro Preto
(urban)
São Bartolomeu
(urban and rural)
Year 1991
(inhabitant nr.)
35241
Year 2000
(inhabitant nr.)
56284
Increase
(inhabitant nr.)
21043
Decrease
(inhabitant nr.)
-
1017
786
-
231
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
The hypothesis of this research is that some factors spatially explicit influence the distribution of degraded vegetation areas, because they can increase accessibility to those areas (roads, slope, distance to
city, village, city, rural settlements, agricultural areas) or enhance the attractiveness for some activities
(geology, drainage, distance to mining sites, tourist sites).
If those factors are influencing degradation, then an investigation of the vulnerable areas for vegetation
degradation is feasible, and can provide important basis for conservation and management strategies.
1.5.
Objectives
The main objectives of the research are:
•
•
•
Assess the variations and distribution of vegetation degradation
Investigate the association between spatial distribution of vegetation degradation and human (roads
network, rural settlements, villages, city, tourist sites, mining sites, agricultural areas) and physical
factors (slope, geology, drainage)
Assess the potential areas at risk of vegetation degradation
Demographic factors
Socio-economic factors
Political factors
Population pressure
Insufficient
development incentives
Inefficient strategies for
management
Encroachment
into
conservation
area
Insufficient
Agriculture’
incentives
Lack of
alternative
activities
Intervention
resumed to
use restriction
Limited
involvement
of local
communities
Insufficient
information
about use and
conservation
Illegal
settlements
Damage
activities
Lack of
information to
tourists
Tourist
pressure
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Cutting
Free grazing
Mining
Lack of
planned
tourism
Fire
Vegetation degradation
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
1.6.
Research questions
The research objectives will be achieved by answering the following research questions:
General
•
What are the human and physical factors that influence the spatial distribution and variations of vegetation degradation, and is it possible to assess areas at risk of vegetation degradation based on those
factors?
Specific
•
•
•
What are the variations and the spatial distribution of vegetation degradation?
What kind of association is there among spatial distribution of vegetation degradation, and the human
(roads network, rural settlements, villages, city, tourist sites, mining sites) and physical factors (slope,
geology, drainage)?
Where might be the areas at risk of vegetation degradation?
1.7.
Hypothesis
The hypothesis of the study can be summarized as:
•
•
The spatial distribution of vegetation degradation is influenced by the human (roads network, rural
settlements, villages, city, tourist sites, mining sites, agricultural areas) and physical factors (slope,
geology, drainage)
It is possible to assess areas at risk of vegetation degradation based on the analysis of the influence of
human and physical factors in the spatial distribution of degraded areas
1.8.
Study area
The EPA Cachoeira das Andorinhas comprises an area of 18700 ha. It is located in the north of the Ouro
Preto Mountain Range, showing variation of elevation from 900 to 1600 meters above sea level. The climate is subtropical moderately humid. The mean annual temperature varies from 19.5ºC to 21.8ºC. The
annual rainfall concentrates in the summer, and varies from 1000 to 2100 mm (Andrade 2000; Messias
1999; Guimarães Neto 1999).
The area is located in the west extreme of the Brazilian Atlantic Forest dominion, setting bounds with the
Savannah dominion (Rizzini 1979). That situation coupled with physical factors, such as elevation and
geomorphology, determine variation on the vegetation formations found in the site. Besides the Atlantic
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Forest, the rocky shrublands formation is distributed through the higher portion of the hills. Some new
plant species were found and described for those formations in the area, for example Pisoniella apolinarii, Oleandra baetae, Hymenophyllum silveirae, Syngonanthus barbatus (Messias 1999). Savannahs
and scrubs, with dominance of Vanillosmopsis erythropappa, are the other vegetation types.
The relief is characterized by the presence of itabirite and quartzite escarpments, and plateaus. The soils
vary with the relief and comprehend cambissoils, latosoils, litosoils and litolic soils. The agriculture activities are limited in the region by the susceptibility to erosion processes and limitations for mechanization due to the abrupt relief, presence of rock fragments and superficial soils (Andrade 2000).
The total population inside the area is 786 people, 233 living in the village São Bartolomeu and 553 in the
rural areas (IBGE 2001). The population groups comprehend small farmers, dwellers of the village São
Bartolomeu and of the rural settlements Maciel, Engenho d’Água and Chapéu do Sol. The agriculture is
mostly of subsistence, including livestock (cattle, horses), cash crops (citrus and guava), horticulture and
fish farm. The Figure 2 presents the location of the study area.
EPA
N
Figure 2: Location of the study area. Background Map Source: Encarta, 1999
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ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
1.9.
Organization of the thesis
The thesis comprehends six chapters and thirteen appendices. Chapter 1 introduces the research, problem
statement, objectives, research questions, hypothesis adopted and study area. Chapter 2 describes the materials required, collected and acquired, and the method used. Chapter 3 presents the analysis and results,
divided in: Land cover and vegetation characterization; Variations and distribution of vegetation degradation; Vegetation degradation distribution in response to human and physical factors; Assessing areas at
risk of vegetation degradation. The Chapter 4 comprehends the discussion of the results. The Chapter 5
presents the general conclusions and recommendations. The references are presented in the Chapter 6 and
are followed by the Appendices.
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
CHAPTER2. MATERIALS AND METHODS
In this chapter the materials and methods used to investigate the spatial distribution of vegetation degradation variations and its association with human and physical factors are described.
1.1.
1.9.1.
Materials
Maps, images, land cover and vegetation data
The maps, images and environmental data used in this study are listed in Table 2, with respective sources.
Table 2: Data and information required and sources
Data and information
required
a- Land cover types
Remote sensing image
Secondary data
Landsat TM image 2000,
Pixel size 30 m (FEAM)
Ground truth
b- Vegetation conditions and environmental factors
Roads
Topographic map 1978,
1: 10000 (IBGE)
Rural settlements, villages, Topographic map 1978,
city
1: 10000 (IBGE)
Tourist , mining sites
Landsat TM image 2000
Contour map
Contour map (FEAM)
Geology map
Geology map (CETEC)
Drainage map
Drainage map (FEAM)
Remote sensing image
Landsat TM image 2000
Degradation indicators
Literature
Broader factors associated to Literature
degradation
1.9.2.
Primary data
Field sampling (78 plots)
Field sampling (6 plots)
Field sampling (47 plots)
Interviews (18)
Equipment
The following instruments were used during the research: Global Positioning System (GPS), slope meter,
compass, altimeter, plant press, pruning hook and measuring tape.
1.9.3.
Software
The software packages used are given in Table 3.
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Table 3: Software used
Software
ILWIS 3.2
ERDAS
SPSS 10.0; MINITAB 13.1
MS EXCEL
MS WORD
1.10.
Application
GIS; Image processing
Image processing
Statistical analysis; graphs
Spreadsheet; graphs
Word processing
Methods
The methods were selected according to the research objectives and questions. The research approach and
methods used are described following.
1.10.1.
Sampling strategy
The stratified random sampling was used in the present study. The method allows the splitting of the
population target into sub-populations, or strata, aiming to reduce within-stratum variance (de Gier 2000;
Kent and Coker 1992). The strata investigated in the field, comprehended forest, scrub, savannah, rocky
shrublands, Eucaliptus plantation, built up areas, pastures and crops. The size of each sample plot was 25
x 25 m and the total number of samples was 78, 47 distributed among the natural vegetation sites and 31
in the other strata (Table 4). The random sample location within each stratum was generated through
EXCEL. However, due to the relief and difficult accessibility to some areas, the priority was made to
those situated in the vicinity of the roads and trails network.
Table 4: Distribution of sample units in the different strata and features
Strata
Forest
Scrub
Savannah
Rocky shrublands
Eucaliptus plantation
Built up areas
Pastures
Crops
Total
1.10.2.
Number of sample plots
20
8
11
8
4
6
14
7
78
Data collection
The location of samples in the ground was made through the utilization of the Landsat TM image 2000,
topographic map and GPS. For each observation point the GPS coordinates were recorded from the center
of the plot and written in the relevee sheet (Appendix 1). Coordinates were also recorded for the tourist
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
and mining sites (6 sample points), that added with the 78 sample plots resulted in 84 observation points
undertaken in the field (Appendix 2).
The diagnosis of vegetation degradation variations in the study area was made with use of ecological indicators, that are intended to provide a simple and efficient way to examine the ecological composition,
structure and function of complex ecological systems (Dale & Beyeler 2001). The fact that there is not
yet a standard developed criteria for vegetation degradation measurement made the task of selection of
ecological indicators for the various vegetation types in the area a challenge. Five ecological indicators
were selected according to the literature (De Pietri 1992; De Pietri 1995; TCM 1998; Hargyono 1993)
and adapted to the situation and vegetation types of the area under study. For the forest areas, invasive
species cover, understory cover and canopy cover were selected. For the savannah and rocky shrublands
formation the indicators used were invasive species cover, bare soil cover and percentage of dead shrubs.
The main data collected in the different land cover is listed in Table 5.
Table 5: Data collected
Degradation
indicators
Structure
characterization
Invasive species
cover
Tree species identification (>10 cm dbh)
Understory cover
Tree species dbh and
height (>10 cm dbh)
Height maximum of
shrubs
Dominant shrubs species
Dominant lower layer
species
Canopy cover
estimation
Bare soil cover
Shrubs number
>1m
Dead shrubs
number
Damage signs
presence/absence:
fire, cutting, free
grazing, fences,
tracks
Eucaliptus
Plantation
Pastures/crops
Number per plot, dbh
and height (> 10cm
dbh)
Type and management
Built up areas,
tourist and
mining sites
Location and
type
The vegetation types discrimination was based on the height of dominant species, physiognomy and species composition. The trees were defined as the plant life forms able to reach a minimum size of 3 m. In
spite of the minimum size of healthy trees adopted was 3 m, the inclusion of dead and injured trees determined a lower size of 2 m, in those cases. Additionally, the measurements of trees in the forest and
scrub areas were limited to those with dbh (diameter at breast height) equal or higher than 10 cm (including palms and ferns). The shrubs were determined as the plant life forms able to reach a height of 1 to 3
16
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
m. This was the case of the shrubs found in the savannah, rocky shrublands and scrub areas. The understory or lower layer of the forest areas included, in this study, shrubs, herbs and seedlings with height
maximum of 3 m.
The invasive species are referred as “organisms which successfully establish themselves in, and then
overcome, otherwise intact, pre-existing native ecosystems” (van Duren 2001). They are also known as
alien invasive species and are considered a threat for the native biological diversity (van Duren 2001). In
the present research, were considered as part of the group of the invasive species, exotic grasses and ferns
(Mellinis minutiflora, Pteridium aquilinum), as well as opportunist species of the native flora. The opportunist species are those that take advantage of situations of disturbance and degradation and spread themselves over larger areas (Arundinaria effusa, Rhynchospora exaltata, among others). The species considered are listed in the Appendix 3.
The estimation of cover for invasive species, understory, bare soil and canopy were made in percentage,
with consideration of the total area sampled in each plot (625 m2). For the verification of the understory
conditions the presence of common species of herbs, shrubs and seedlings was notified. The species considered included, among others: Leandra scabra, Coccosypselum erythrocephalum, Diodia brasiliensis,
Psychotria tetraphylla, Miconia spp, ferns and bromeliads.
The identification of plants species was made using own expert knowledge, literature (Lorenzi 1992), and
consultation to the Herbarium Professor Jose Badini of the Federal University of Ouro Preto (OUPR).
For the understanding of the overall environmental and socio-economic problems related to vegetation
degradation in the area 18 interviews were conducted: 5 (to villagers and rural settlers); 7 (farmers); 1
(mining worker); 5 (key actors from organizations involved in the management of the area - FEAM, IEF,
UFOP). The semi-structured questionnaire used is shown in the Appendix 4. The interviews were used
for the understanding of the vegetation degradation process in the study area and for supporting discussions and recommendations.
1.10.3.
Digitizing, image processing, classification and data processing
The digitizing was carried out for the roads, rural settlements and village using the Topographic map
1978. The Landsat TM image 2000 and other maps were georeferenced by the team of the agencies that
collaborated for the thesis research, but some adjustments were made in the GIS environment to unify the
data obtained from different sources.
For the fieldwork, stretching, filtering and unsupervised classification techniques were undertaken beforehand. The hard copy used was a false color composite (combination of bands 4,5,3) for improvement
of discrimination of vegetation areas.
The classification of the Landsat TM image 2000 into land cover classes was carried out through a cluster
of steps of supervised classification including: selection and use of training sets (sample points), classification using the maximum likelihood classifier, application of majority filter, generation of output and
accuracy assessment.
17
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
The DEM (Digital Elevation Model) was obtained from a digitized contour map aiming the creation of
the slope map. Line interpolation technique was used.
The primary and secondary data collected and acquired were divided into dependent and independent
variables presented in Table 6 and Table 7. The classes of vegetation degradation defined comprehended:
not degraded, low degraded, moderately degraded, highly degraded and extremely degraded. Forest and
scrub were grouped together during the data processing, since the occurrence of scrub is related to the
forest degradation process. Savannah and rocky shrublands formed the other group, considering the fact
that the same indicators were useful for both. The direction of the influence of each indicator in the vegetation degradation process was defined through the use of multivariate analysis (Principal Component
Analysis/PCA – described in 2.2.4). Higher proportion of invasive species cover, lower estimation of
canopy cover and lower proportion of understory cover meant higher level of degradation in the forest
areas. The higher degradation condition in the savannah and rocky shrublands formations was determined
according to the higher proportion of invasive species cover, higher proportion of bare soil and higher
percentage of dead shrubs. The definition of each class of vegetation degradation was made by the sum of
the values obtained for each of the indicators and verification of what it represented considering the highest value possible in each of the vegetation group (12). The classes were intended to provide a basis for
the investigation of spatial distribution of vegetation degradation variations. The criteria, threshold values
and weights used for different indicators are presented on the Appendix 5. The establishment of classes
expressing the levels of vegetation degradation can bring about some subjectivity, due to the need of use
of arbitrary endpoints and weights. Although expert opinion and judgement is referred by Andreasan et al
(2001) as part of the choice of relevant degraded locations and scale metrics of degradation, the use of
PCA (2.2.4) granted confidence to the categorization of sample plots in low, moderately, highly, extremely and not degraded classes. The scores generated in the PCA (2.2.4) gave the numerical expression
of the vegetation degradation.
The values of independent variables were mostly obtained in the GIS environment during the evaluation
of the distribution of vegetation degradation variations in relation to distance to the roads, rural settlements, village, city, tourist sites, mining sites, agricultural areas and drainage. The rural settlements, village and city map comprehended Maciel, Engenho d’Água, Chapéu do Sol, São Bartolomeu and Ouro
Preto neighborhoods. The tourist sites map comprised Andorinhas waterfall, São Bartolomeu waterfall,
São Bartolomeu and Ouro Preto neighborhoods. The mining sites included the quartzite exploitation
(close to Ouro Preto) and the Capanema Mining Co., located in the boundary north of the EPA. In the
case of slope, a slope percentage map was obtained from the DEM (Digital Elevation Model). The geology map was generalized in two categories. The rocky formations grouped the quartzite, itabirite, schist,
and phyllites. The other group (not rocky) comprehended the sedimentary deposits. The investigation of
geology was based on the presence or absence of rocky formations, since the presence of rocks could be a
source of attraction for some activities, such as mining.
Table 6: Vegetation degradation scores (dependent variable)
Variable
Vegetation
degradation
Zero
Not degraded
One
Low
graded
Classes
Two
de- Moderately
degraded
18
Three
Highly
Degraded
Four
Extremely
degraded
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
scores
Table 7: Human and physical factors (independent variables)
Variables
Human factors
Distance
Distance
Distance
Distance
Distance
Slope
to
the to village, to tourist to mining to agriculroads
city, rural sites
sites
tural areas
settlements
1.10.4.
Physical factors
Geology
Distance
to
the
drainage
Statistical analysis
The analysis of the categorization of vegetation observation points into degradation classes and the definition of values for the degradation situation of each sample plot was implemented through the use of an
ordination method, the Principal Component Analysis (PCA). The PCA is performed to summarize environmental data and to produce an ordination of the sample plots, based on the environmental variables
(Kent & Coker 1992). It aims to provide an understanding of the underlying data structure and to standardize the measurements. The use of PCA allowed the investigation of how good and in which direction
each of the indicators used could be related to vegetation degradation. The technique constructs the theoretical variable that minimizes the total residual sum of squares after fitting straight lines to the environmental data (Jongman et al 1995). Through the PCA the most important components, that account for the
higher variability are generated with respective eigenvalues or scores (Kent & Coker 1992). The scores of
the best principal component were used to represent numerically the vegetation degradation variations in
the area. They were obtained by the multiplication of the original values of each variable (Appendix 6) by
the variable eigenvector value. Additionally, the PCA was performed for checking redundancy in the data
and selection of the independent variables to be used in the regression analysis. For the dependent variables, that had the same scale measurements, the covariance matrix was used to calculate the principal
components. The independent variables had the principal components calculated through the correlation
matrix, in order to standardize variables.
The equations of the PCA are (Jongman et al 1995):
n
bk= ∑
yki xi
i=1
Where bk is the slope parameter for the variable k, yki the centred abundance of the variable k (indicators) at the site i and xi the score of the variable at site i.
m
xi=∑
yki bk
k=1
Where xi refers to site scores (vegetation degradation)
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ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
yki=(bk1 xi1 + bk2 xi2) +residual
Where bk1 and bk2 are the scores of the variable k; xi1 xi2 are the scores of site i on Axis 1 and Axis 2,
respectively.
The normality test of Kolmogorov-Smirnov was performed to examine whether or not the variables followed a normal distribution. The Kolmogorov-Smirnov is an empirical cumulative distribution function
based test. The test performs a hypothesis test where the null hypothesis states that the data follow a normal distribution. The alternative hypothesis states that the data do not follow a normal distribution. The
normality test provides indication whether to use parametric statistics (variables close to normal distribution) or non parametric statistics (variables not normally distributed). The latter tests are known as distribution-free tests, because they make no assumptions about the underlying distribution of the data.
The hypothesis statement of the normality test is:
Ho: Fo (X) =SN(X) (null hypothesis) versus
Ha: Fo(X) ≠ SN(X) (alternative hypothesis)
Where Fo(X) Is theoretical normal cumulative distribution and SN(X) is the observed cumulative frequency distribution of the variable at N observations.
In order to investigate the relationship among the variations in vegetation degradation (scores) and human
and physical factors, and furthermore to support the prediction of areas under risk of degradation, regression and correlation analysis were performed. Regression analysis is a statistical method that describes
the response variable as a function of one or more explanatory variables (Jongman et al 1995). The
method is used for assessing which environmental variables contributes more to the response, and to predict environmental responses on sites from the observed value of one or more variables. The correlation
analysis is used to determine the strength of relationships between variables. The result of a correlation
analysis (correlation coefficient - r) is a statistic lying between –1 to +1, which describes the degree of
relationship between two varibles (Kent & Coker 1992). The correlation coefficient is used to describe
the success of regression in explaining the response y (More & McCabe 1998). The prediction of areas at
risk of vegetation degradation used as input variables (factors) those that presented p values significant at
α = 0.05, for a one-tailed test.
The regression equation is (Jongman et al 1995):
y = bo + b1x + ε
Where y is the response variable; x is the explanatory variable; ε is the error; and bo and b1 are fixed but
unknown coefficients corresponding to the intercept and slope parameters, respectively.
The hypothesis statement of the relationship vegetation degradation and human and physical factors,
through correlation analysis is:
Ho: ps = 0 (null hypothesis) versus
20
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Ha: ps ≠ 0 (alternative hypothesis)
Where ps is the population correlation coefficient.
The overall accuracy of the land cover map was calculated in a Confusion Matrix. The overall accuracy is
represented by the ratio of the number of correctly classified pixels by the total number of pixels checked
or sampled. For the land cover mapping half o the sample plots (39) were used, and the other half (39)
were used for the accuracy assessment. A general overview of the methods is presented in Figure 4.
21
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Landsat TM
Image 2000
Topographic
Map
Classifica-
Digitizing
Land Cover
Map
Settlements/
Village Map
Contour Map
Drainage
Map
Geology
Map
DEM
Roads
Map
Slope
Map
Agricutural
A
M
Spatial and Statistical Analysis
Training set
Vegetation
Map
Vegetation
degradation Point
Field Data:
Observation Points
Tourist
Sites,
Mining Sites
GIS
Opera-
Map of vegetation degradation distribution
GIS
Opera-
Map of areas at
risk
of vegetation
degradation
Figure 4: General overview of methods
22
Relationship factors/vegetation
degradation
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
CHAPTER 3. RESULTS
The results are presented in four parts starting with a characterization of the land cover and vegetation in
the study area, aiming to provide a general idea of the spatial distribution and qualitative aspects of the
different environments, specially the vegetation. The situation of the observed vegetation sample plots
regarding variations and distribution of vegetation degradation is described in the second part, and was
used as a basis for the investigation and understanding of the association among vegetation degradation
and human and physical factors. The resulted significant responses were used to assess the vegetation
areas at risk of degradation and comprehend the last part of this chapter.
3.1 Land cover and vegetation characterization
The land cover and vegetation in the EPA Cachoeira das Andorinhas, derived from the Supervised classification of the Landsat TM image 2000, resulted in 7 land cover classes, shown in Map 1.
Map 1: Land cover map of the Environmental Protection Area Cachoeira das
Andorinhas, derived from supervised classification of Landsat TM image 2000
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ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
The Table 8 shows the area in hectares covered by each class. The forest class covers the largest area in
the EPA Cachoeira das Andorinhas, followed by scrub, savannah and pastures. The rocky shrublands
formation, built up areas and Eucaliptus plantation cover a smaller proportion of the study area.
Table 8: Land cover classes and area size derived from supervised classification of Landsat TM
image 2000
Land cover
Forest
Savannah
Rocky shrublands
Scrub
Eucaliptus plantation
Pasture
Built up areas
Area
(ha)
10 744
1656
650
3866
57
1550
177
The characterization of the land cover classes and map accuracy assessment is given following.
1.10.5.
Forest
The forest distributed through the EPA Cachoeira das Andorinhas is a semi-deciduous seasonal forest
characterized by partial loss of tree leaves during the dry season (april - september). It is distributed
through the hilly areas, mainly in the sedimentary deposits. The forest found in the sampled areas, can be
divided into three categories, according to the succession stage and structural complexity of the vegetation: forest advanced stage (FAS - capoeirão), forest intermediate stage (FIS - capoeira) and scrub (SC –
matas de candeia and macega).
The FAS showed trees height of 25m maximum. The total number of trees found in the sampled units
(0.625 ha – 10 sample plots) with dbh (diameter at breast height) higher or equal to 10 cm was 615. An
amount of 69 individuals or 11% of the total number of trees was found dead. The density average of individuals /ha was 984. The estimated canopy cover average was 45%. The FIS showed trees height of 15
m maximum. The total number of trees assessed was 341(0.625 ha – 10 sample plots). From the total
number of trees sampled, 14 or 4% were found dead. The density average of individuals/ha was 446 and
average canopy cover 35%.
Comparisons in the vertical (height) and horizontal (dbh) structures of the two categories are shown in the
Figures 5 and 6. The number of trees was higher in the FAS areas, but the diameter distribution (dbh
≥10cm) followed the same shape as FIS, with higher amount of trees in the class 10-20cm. The distribution on the higher classes (30-40 cm; > 40 cm) of diameter was slightly predominant in the FAS areas.
The tree height distribution (dbh ≥ 10 cm) followed the same pattern in FAS and FIS for the classes 2-7 m
and 7-12 m, with increase of representation of individuals in the latter. In the case of the class 12-17 m, a
higher amount of trees was observed for the FAS areas. Additionally, only in the FAS samples occurred
representation in the class over height 17 m.
24
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Figure 5: Distribution of trees in height classes in
Figure 6: Distribution of trees in diameter
classes
in the forest intermediate and advanced stage
the forest intermediate and advanced stage
The tree species composition presented a total of 95 species (identified at least at botanic family level), 39
common for the FAS and FIS areas, 34 occurring only in the FAS and 22 in the FIS (Appendix 5). In the
FAS a total of 15 individuals were found unknown and 31 (5% of the total) had no leaves, making the
task of identification unfeasible. For the FIS, 3 individuals were unknown and 10 (3%) had no leaves, due
to the deciduous behavior of the trees in the study area.
Many of the species found are pioneers such as Cecropia hololeuca, Clethra scabra, Cordia sellowianna,
Hyptiodendron asperrimum, Vismia brasiliensis and Vanillosmopsis erythropappa. The latter cited species has a high importance in terms of use by the local people, not only for fuelwood production, but also
as building material. Some other species found are secondary, for example, Sclerolobium rugosum,
Guarea guidonia, Anadenathera colubrina. A number of woody species has potential commercial use
including Aspidosperma parvifolium, Cupania vernalis, Bowdichia virgilioides, Copaifera langsdorffii,
Machaerium villosum, Myrcia rostrata, Xylopia sericea, Vanillosmopsis erythropappa (IEF 1994). The
tree like fern species, Cyathea arborea, occurred in the areas investigated. One species found in the FAS,
Ocotea odorifera, is threatened of extinction according to the Red List of Threatened Plant Species of
Minas Gerais State (Mendonça & Lins 2000).
The species composition of the understory was similar for the two categories and included the presence of
Leandra scabra, Coccosypselum erythrocephalum, Diodia brasiliensis, Psychotria tetraphylla, Miconia
spp, as well as some ferns, bromeliads and seedlings.
25
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Although differences in structure were found between FAS and FIS, they were merged as one group (forest), since the spectral reflectance was similar and the dn (digital number) values for pixels overlapped in
many cases (Map 1).
The scrub (SC) comprehends the forest areas that have been regenerating for a shorter time and consequently the structure is less complex and poorer comparing to the FAS and FIS. It also includes abandoned pasture and agricultural areas. Two different types of scrub were found: scrub with small trees (ST
– matas de candeia) and scrubs with predominance of shrubs (SS - macega). In both cases Vanillosmopsis
erythropappa was found an important dominant species.
The ST presented height maximum of 7 m and few trees reaching trunk diameter at or over 10cm. The
maximum canopy cover estimated on those areas was 20%. Besides Vanillosmopsis erythropappa, other
pioneer trees were found, for example, Clethra scabra, Vismia brasiliensis, Lithraea molleoides, Lamanonia ternata, Rapanea umbellata. The understory showed varied composition with some savannahs’ and
other common species combined, such as Byrsonima coccolobifolia, Jacaranda caroba, Baccharis
dracunculifolia, Vernonia polyanthes, Lantana lilacina.
The SS showed predominant cover of shrubs and herbs, with height maximum of 2 m. The species composition was largely dominated by invasive and opportunist species, that spread easily over open areas,
with high sun light availability. Some of the species found were pastures’ grasses coupled with others
such as, Vannilosmopsis erythropappa, Vernonia polyanthes, Lantana lilacina, Baccharis dracunculifolia, Achyrocline satureoides, Chamaecrista sp, Eupatorium sp.
The different spectral reflectance showed by the scrub in relation to the other forest succession stages
made it possible to map them separately, as one land cover class (scrub - Map 1).
1.10.6.
Savannah
The brazilian savannah like formation (cerrado) is distributed through the north part of the study area
(Map 1). Three different forms of savannah are found in the site: savannah with dominance of grasses
(campo limpo), savannah with sparse shrubs (campo sujo) and savannah with short trees (campo cerrado).
In all of them, a continuous grass layer is found, interrupted in some places by shrubs and/or short trees.
In spite of the physiognomy differences, not many variations in the species composition was found in the
areas under study. The height maximum of trees in the savannah areas was 7 m with an average of 4 m.
Vochysia tucanorum, Byrsonima verbascifolia, Tabebuia ochracea, Dydimopanax morototoni, Roupala
montana, Eugenia dysenterica, Erythroxyllum suberosum, Sthryphnodendron adstringens and Rapanea
sp were some of the most common short trees found. Those species were also found in shrub form, distributed sparsely among the grass cover.
The lower layer comprehends a continuous layer of grasses and herbs, some of them members of the
neighboring rocky shrublands formation. The species composition included Echinolaena inflexa, Lippia
sp, Heteropteris sp, Microlicia spp, Cambessedesia spp, Erythroxyllum spp.
26
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
1.10.7.
Rocky shrublands
The rocky shrublands (campo rupestre) is distributed through the quartzite and itabirite rocks formation in
the north, south and east regions of study area (Map 1). Rocks interrupted sparsely by the layer of shrubs
and herbs dominate the ground cover.
Some variations are found among the rocky shrublands of the area depending on the rock type. The most
important shrub species found were Lychnophora linearis, Lychnophora spp, Diplusodon sp, Baccharis
sp, Vellozia compacta, Marcetia sp, Periandra mediterranea, Lavoisiera sp, Tibouchina sp and Vannilosmopsis capitata. The herbs comprehended many ornamental species of orchids, such as, Laelia flava,
Epidendrum ellipticum, Oncidium sp, Bulbophyllum sp. Other species found were Dickia coccinea, Paepalanthus planifolius, Paepalanthus aequalis, Vellozia gramineae, Syngonanthus sp.
1.10.8.
Eucaliptus plantation
The main species of the plantation forest in the area is Eucaliptus sp, an exotic species. The plantations
are distributed irregularly in areas in the south and north of the EPA. Most of the plantations are managed
by the private owners and the principal purpose is commercial, specially regarding charcoal production.
Variations on the age of the stands and consequently in height of the trees were found. In the older ones
the height maximum was around 20 m. The unsderstory was found invaded by species of the neighboring
vegetation formations and invasive species, such as Pteridium aquilinum.
1.10.9.
Agricultural areas
The most evident agriculture activity in the area is cattle raising and the pastures are established for the
livestock grazing. The grasses species used are mainly Brachiaria spp, but in some cases the lack of appropriate management facilitates the invasion and establishment of other species such as Mellinis minutiflora and Pteridium aquilinum.
The agriculture crops are in the majority situated close to the houses and villages and do not cover extensive areas. For that reason, they were not classified as a specific category and were mapped combined
with the pastures and built up areas. From the 7 sample plots undertaken citrus, guava and other fruit
plantation were found in all the areas. Vegetable horticulture was found in 4 plots and annual crops (corn)
in 3. Only one of the areas visited had a commercial organic vegetable horticulture activity, and in the
other areas the crops were grown for subsistence purposes. In the case of guava and citrus, some families
in São Bartolomeu and Engenho d’Água have been developing the production of fruit sweets, that is sold
to stores in Ouro Preto and other cities.
1.10.10.
Built up areas
The built up areas are usually comprised of areas of intensive use with much of the land covered by structures (Anderson 1976). In the EPA Cachoeira das Andorinhas they comprehend the settlements, villages,
27
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
farms, houses and transportation facilities inside the area. Most of the built up areas are distributed
through out the flat and undulating slope or following the drainage system of the Velhas river.
1.10.11.
Map accuracy
The accuracy of the map is showed in the error matrix (Table 6). The table shows the derived errors and
accuracy expressed as percentages. A total of 78 observation points were sampled in the field, 39 used as
training set during the supervised land cover classification, and 39 for accuracy assessment. The overall
accuracy refers to the number of correctly classified pixels, that in the case were 32, divided by the total
number of pixels (39). The overall accuracy obtained was 82 %. The user accuracy is the probability that
a reference pixel has been correctly classified, and it is calculated by dividing the diagonal value of each
class by the column total. The producer accuracy is the probability that a pixel classified on the map
represents that class on the ground (Anderson 1976). The values obtained for the producer and user accuracy were 85% and 78% respectively.
Table 6: Error matrix after land cover classification – Landsat TM image 2000
Eucalytus
plantation
Scrub
Forest
8
0
0
0
2
0
0
10
Producer
Accuracy %
80
Rocky shrublands
Savannah
0
2
2
0
0
0
0
4
50
0
0
7
0
0
0
0
7
100
Eucalyptus
Plantation
1
0
0
2
0
0
0
3
67
Scrub
0
0
0
0
4
0
0
4
100
Pasture
0
0
0
0
0
7
1
8
88
Built up areas
1
0
0
0
0
0
2
3
67
Total
10
2
9
2
6
7
3
39
78
89
100
78
100
67
85
Land cover
types
User Accuracy %
Overall Accuracy %
Forest
Rocky
shrublands
Savannah
82
28
67
Pasture
100
Built Total
up
areas
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
1.11.
Variations and distribution of vegetation degradation
The results of the categorization of the 28 sample plots of the forest and scrub areas into vegetation degradation conditions are presented in the Table 7. The criteria, threshold values and original data used are
shown in Appendices 5, 6 and 7. From the total areas sampled, 8 cases or 28% were classified as extremely degraded (class four), 10 units or 36% as highly degraded (class three), and 10 cases or 36% were
found moderately degraded (class two). The forest intermediate stage presented 60% of the sample plots
classified as highly degraded and 40% as moderately degraded. The forest advanced stage, otherwise,
comprehended 40% of sample units classified as highly degraded and 60% as moderately degraded. The
scrub areas were all (100%) classified as extremely degraded. For the savannah and rocky shrublands
formations (Table 8), in the totality of 19 sample plots, 2 cases or 10 % were found extremely degraded
(class four), 1 case or 6% presented highly degraded (class three), 7 units or 37% were classified as moderately degraded (class two), 7 cases or 37% low degraded (class one) and 2 cases or 10% not degraded
(class zero). The savannah had 9% of the sample plots classified as highly degraded, 46% as moderately
degraded, 36% as low degraded and 9% as not degraded. The rocky shrublands comprehended 25% classified as extremely degraded, 25% moderately degraded, 38% as low degraded and 12% as not degraded.
The vegetation degradation scores were generated in the PCA
and used as input data for the regression analysis.
29
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Table 7 - Categorization of sample plots of the forest areas according to vegetation degradation indicators Ia, % invasive species cover; Ib, % understory cover; Ic, % of canopy cover
Table 8 - Categorization of sample plots of the savannah and rocky shrublands areas according to
Sample
Plots
Type
Sample
1
Plots
2
3
14
25
36
47
58
69
710
811
912
1013
1114
1215
1316
1417
1518
1619
1720
1821
19
Type
FIS
FIS
FIS
SA
FIS
SA
FIS
SA
FIS
SA
FIS
SA
FIS
SA
FIS
SA
FIS
SA
FAS
SA
FAS
SA
FAS
SA
FAS
RS
FAS
RS
FAS
RS
FAS
RS
FAS
RS
FAS
RS
FAS
RS
ST
RS
Ia
Ib
Ic
Ia2
2
3
33
32
01
33
22
11
02
23
13
01
01
11
01
02
01
12
11
24
2
Id3
2
3
23
13
03
03
11
13
23
13
13
12
01
03
03
03
03
23
23
40
4
Ie2
2
2
22
13
32
12
02
22
22
12
12
01
02
11
22
32
02
22
22
23
4
Vegetation Classes
Degradation
Scores
Classes
Vegetation
-6.816
3
Degradation
-10.504
2
Scores
20.553
3
70.965
3
27.488
3
62.608
2
6.914
3
1.425
1
-21.307
2
48.332
2
29.753
3
30.965
12
-19.634
20.719
22
-19.053
22.127
23
0.049
34.830
23
20.553
0.570
13
32.007
3.640
12
-47.215
0.000
02
-37.944
3.815
12
-30.508
1.083
12
-15.294
1.824
13
8.456
0.000
02
-7.658
29.471
23
3.085
36.360
22
-3.057
100.823
44
51.892
93.542
4
vegetation degradation indicators Ia, % cover of invasive species; Id, % of bare soil cover; Ie, relative % of dead shrubs
The Principal Component Analysis (PCA) was performed aiming to verify in which way and in what proportion the indicators used for characterizing vegetation degradation were actually explaining the process.
In the forest areas, the results (Table 9) revealed variance or eigenvalue of 1093.4 for the first principal
component that accounted for 77% of the total variance. Together, the first two and the three components
represented 90% and 100% respectively of the total variability. Therefore, the first component was found
representative of the overall vegetation degradation variance, since the remained principal components
accounted for a very small proportion of the variability. The scores of the first principal component were
used to represent numerically the vegetation degradation situation of each plot (Table 7).
Table 9: Eigenvalues obtained in the Principal Component Analysis (PCA) for the first, second and
third component – Forest areas
30
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Eigenvalues
Eigenvalues
First Component
1093.4
Percentages
Cumulative
ages
Percent-
Second Component
191.3
Third Component
133.0
0.771
0.135
0.094
0.771
0.906
1.000
The variables factor loadings or eigenvector values resulted from the PCA (Table 10), are a set of scores,
that represents the weighting of each of the original variable on each component. They are scaled like correlation coefficients and range from +1 to –1. The nearest the score is to +1 or –1, or the furthest away
from zero, the more important is that variable in terms of weighting that component (Kent & Coker 1992).
In the first component the variables’ eigenvectors (Table 10) were positive for the indicator invasive species cover and negative for the understory cover and canopy cover. The indicator invasive species cover
had the highest weight (0.764) followed by canopy cover (-0.453) and understory cover (-0.460). The direction of the influence of each variable of the first component was used to determine the orientation of
the vegetation degradation classes weighting (Appendix 5). Thus, the variable invasive species cover was
considered positively correlated with the vegetation degradation process. Understory cover and canopy
cover were arranged negatively related to the process, since they presented negative eigenvector values.
The orientation and weighting importance of the variables in the first and second components can be
visualized in the ordination diagram, presented in the Figure 7. In the diagram, the variable invasive species cover is located much further of the center in comparison with the other two, and lies in the positive
region of the axis x (first component) and axis y (second component).
Table 10: Eigenvector values of the Principal Component Analysis (PCA) for the variables invasive
species cover, understory cover and canopy cover – Forest areas
Eigenvectors (Factor loadings)
First Component
Second Component
Third Component
Variables
Invasive species cover
Understory cover
Canopy cover
0.764
-0.453
-0.460
0.644
0.492
0.585
0.039
0.743
-0.660
Variables
0.8
0.6
C
Second component
I
U
0.4
0.2
0
-0.6
-0.4
-0.2
-0.2
0
0.2
0.4
-0.4
-0.6
31
First com ponent
0.6
0.8
I- Invasivespecies
cover
U- Understory
cover
C- Canopy cover
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Figure 7: Diagram of the variables invasive species cover, understory cover and canopy cover,
showing the eigenvectors values along the first component and the second component axis
The analysis of the correlation between the vegetation degradation scores generated and vegetation degradation classes in the forest areas showed that there is high correspondence between them (R2 0.8197 Figure 8), which granted confidence to the classification of vegetation degradation based on weights.
Vegetation Degradation Classes
4
3
R2 = 0.8197
2
1
-15
-10
-5
0
5
10
15
Vegetation Degradation Scores (PCA)
Figure 8: Straight line fitted by linear regression of the relationship vegetation degradation classes
and PCA scores (used to represent numerically the variations in vegetation degradation) in the forest areas
The results of the PCA for the savannah and rocky shrublands formations are shown in Table 11. The first
principal component exhibited variance (eigenvalues) of 1046.4 and comprehended 69% of the total variance. The first two and the three components together explained 94% and 100% respectively of the total
variability. The first component represented the overall vegetation degradation variance in those formations, while the remaining principal component responded for a very small proportion of the variance.
Table 11: Eigenvalues obtained in the Principal Component Analysis (PCA) for the first, second
and third component – Savannah and Rocky shrublands formations
Eigenvalues
Eigenvalues
Percentages
Cumulative
ages
Percent-
First Component
1046.4
Second Component
385.9
Third Component
78.5
0.693
0.255
0.052
0.693
0.948
1.000
32
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
The variables’ eigenvectors for the savannah and rocky shrublands areas are shown in Table 12. All the
three indicators had positive eingenvectors values and this information supported the weighting process,
for vegetation degradation classes definition (Table 8 - Appendix 5). In the first component the variable
bare soil cover had the highest value (0.728), and can be considered the most important in terms of influencing the vegetation degradation ranking in those sites. Invasive species cover presented the second
highest value (0.683) and dead shrub percentage had a very small participation in the definition of the
vegetation degradation variance (0.057). The Figure 9 shows the distribution of the three indicators used
in the savannah and rocky shrublands, according to their eigenvector values in the first and second components. It can be seen, that bare soil cover and invasive species cover presented values farther from 0,
contributing consequently in higher proportion to the vegetation degradation level definition
Table 12: Eigenvectors values of the Principal Component Analysis (PCA) for the variables invasive species cover, understory cover and canopy cover – Savannah and Rocky shrublands
Eigenvectors (Factor loadings)
First Component
Second Component
Third Component
Variables
Invasive species cover
Bare soil cover
Dead shrubs %
0.683
0.728
0.057
0.721
-0.659
-0.215
0.119
-0.188
0.975
Variables
0.8
B
B- Bare soil cover
I- Invasive
species cover
D- Dead shrubs %
Second component
0.6
0.4
0.2
0
-0.8
-0.6
-0.4
-0.2
-0.2
-0.4
0
0.2
0.4
0.6
0.8
D
I
-0.6
-0.8
First com ponent
Figure 9: Diagram of the variables bare soil cover, invasive species cover and percentage of dead
shrubs, showing the eigenvectors values along the first component axis and the second component
axis
The high correlation (0.848) found among the scores obtained in the PCA in relation to the classes of
vegetation degradation generated (Table 8 - Appendix 5), supported the utilization of both as an expression of the vegetation degradation variations (Figure 10).
33
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
5
Vegetation Degradation Classes
R2 = 0.848
4
3
2
1
0
0
20
40
60
80
100
120
Vegetation Degradation Scores (PCA)
Figure 10: Straight line fitted by linear regression of the relationship vegetation degradation classes
and PCA scores (used to represent numerically the variations in vegetation degradation) in the savannah and rocky shrublands areas
The analysis of the presence and absence of damage activities in the sample plots totality (47) showed
that signs regarding grazing, fire, cutting, mining and tourism activities were present in all the sampled
areas (Figure 7). The importance of the activities was different for the various vegetation types. Activities
of cutting and grazing were found in higher proportion in the FIS (40% and 50% respectively) and FAS
(40% and 70%), while the presence of fire was evidenced only in the FIS (10%). Signs of fire occurred in
higher proportion in the scrub (100%), savannah (100%) and rocky shrublands (100%) areas. Grazing
activities were also testified as important in those areas, occurring in 88% of the scrub areas, 90% of the
savannah areas and 75% of the rocky shrublands. Indicators of mining activities, on the other hand, were
restricted to the rocky shrublands areas (25%), due to the presence of the rock substrate, specially quartzite, target of exploitation. Besides that, garbage signs (cans, plastics, etc) from tourist activities were observed only in the rocky shrublands (25%).
The situation found in the study area, regarding fencing system and presence of tracks is presented in the
figure 8 shows. Those indicators contribute to vegetation degradation, since they potentially increase the
accessibility of livestock and humans to the natural vegetation areas. From the 47 sampled areas 87%
showed the presence of tracks, and 81% the absence of fences.
34
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Figure 11: Occurrence of the damage activities (fire, Figure 12: Distribution of the indicators tracks
grazing, cutting, mining, tourism) in the different ve- and fences according to their presence and abgetation types, in the sample plots
sence in the sample plots investigated
The distribution of the classified observation points according to vegetation degradation levels is presented in the Map 2. An attempt was made to map the spatial distribution of the different degradation
classes. The low number of not degraded situations to limit the spatial distribution of the degraded areas,
made unfeasible the task to extrapolate the degradation situation for the whole vegetation areas. Moreover, an analysis of the vegetation degradation classes in the GIS environment showed a weak clustering
capability for most of the classes, similarities in the spectral characteristics, and consequent overlapping
in some classes (Figures 13 to 16). The spatial distribution map was consequently generated only for the
extremely degraded scrub areas, that showed a distinctive spectral response and clustering in relation to
the other categories (Map 3), and was obtained during the procedures of supervised classification of the
land cover.
35
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Map 2: Distribution of categorized vegetation degradation points, investigated in the Environmental
Protection Area Cachoeira das Andorinhas
Figure 13 – Representation of clusters in
the feature space, of the three vegetation
degradation classes in the forest areas
(bands 3 and 5). Note mixing in the
spectral characteristics of moderately
and highly degraded classes
Figure 14: Representation of clusters of
vegetation degradation classes in forest areas,
in the feature space (bands 4 and 7). Note
stronger clustering capability of extremely
degraded class
36
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Figure 15 – Representation of clusters in
the feature space, of the five vegetation
degradation classes in the savannah and
rocky shrublands (bands 3 and 5). Note
weak cluster capability and mixing of
spectral characteristics of various classes
Figure 16: Representation of clusters of
vegetation degradation classes, in savannah
and rocky shrublands, in the feature space
(bands 4 and 7). Note mixing of spectral
characteristics in the different classes
Map 3: Spatial distribution of the extremely degraded vegetation areas or scrub, in the Environmental Protection Area Cachoeira das Andorinhas
1.12.
Vegetation degradation in response to human and physical factors
The verification of the influence of the human and physical factors in the vegetation degradation of the
study area is presented below. An investigation of the data structure and selection of variables, aiming at
redundancy reduction and synthesis of the environmental data used, is presented at first.
1.12.1.
Descriptive statistics and selection of variables
The descriptive statistics of the variables is shown in Appendix 9 and the results of Kolmogorov-Smirnov
test of normality of the data are shown in Appendix 10. For the forest areas most of the variables presented normally distributed and the following were not normally distributed: distance to the roads and
distance to agricultural areas. In the savannah and rocky shrublands half of the variables were found normally and half not normally distributed. The normally distributed ones comprised: distance to mining
37
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
sites, distance to agricultural areas, distance to the drainage, slope, geology and dead shrub percentage.
The not normally distributed were: vegetation degradation scores, distance to the roads, distance to village/city/rural settlements, distance to tourist sites, invasive species cover and bare soil cover.
The Principal Component Analysis (PCA) was used for the selection of independent variables (human
and physical factors) target of investigation, in order to avoid redundancy. The results of the PCA in the
forest and savannah areas are shown in the Appendices 10 and 11. In the forest areas the human factors
variables selected were distance to village/city/rural settlements, distance to mining sites and distance to
roads. In the Figure 17 it is shown the ordination of the variables along the first and second component
axis. The human factors distance to agricultural areas and distance to tourist sites presented clustered to
village/city/ rural settlements, with scores very close to zero, and were removed from the analysis. The
distance between two points in the PCA diagram is an indication of the similarities between variables.
The closeness to zero indicates less influence in the process under consideration.
Variables
R
R- Roads
M- Mining sites
T- Tourist sites
A- Agricultural
areas
V- Villages
0.8
Second component
0.6
0.4
V
0.2
A
-0.6
-0.4
T
0
-0.2
-0.2
0
0.2
0.4
0.6
0.8
-0.4
-0.6
M
First com ponent
Figure 17: Diagram of the human factors variables in the forest areas, showing the eigenvectors
values along the first and the second component axis, and data redundancy expressed by clustering
among distance to village/city rural settlements, distance to tourist sites and agricultural areas
The physical variables distance to drainage, geology and slope presented apart from each other, and were
all selected for the analysis in the forest areas (Figure 18).
38
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Variables
1
D- Drainage
G- Geology
S- Slope
G
Second component
0.8
0.6
0.4
0.2
-1
-0.8
S
-0.6
0
-0.2-0.2 0
-0.4
0.2
0.4
0.6
-0.4
D
0.8
1
-0.6
-0.8
-1
First component
Figure 18: Diagram of the physical factors variables in the forest areas showing the eigenvectors
values along the first and the second component axis, and distinct distribution of variables
For the savannah and rocky shrublands formation the human factors variables selected were distance to
tourist sites, distance to mining sites, distance to agricultural areas and distance to roads. The variable
distance to village/city/ rural settlements was clustered to tourist sites, with value of the second component very close to 0 and was removed from the analysis (Figure 19).
Variables
R- Roads
M- Mining sites
T- Tourist sites
A- Agricultural
areas
V- Villages
0.8
R
Second component
0.6
0.4
M
0.2
V
-1
-0.8
-0.6
-0.4
0
-0.2
0
-0.2
0.2
0.4
0.6
0.8
1
-0.4
A
T
-0.6
-0.8
First com ponent
Figure 19: Diagram of the human factors variables in the savannah and rocky shrublands areas,
showing eigenvectors values along the first and the second component axis, and clustering of the
variables distance to distance to village/city/rural settlements and distance to tourist sites
39
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
In the case of the physical factors variables, the situation was similar to the forest areas, with the three
variables located apart from each other along the first and second component axis (Figure 20). Indeed,
distance to drainage, geology and slope were kept in the analysis.
Variables
0.9
G
Second component
0.6
D- Drainage
G- Geology
S- Slope
0.3
D
0
-0.9
-0.6
-0.3
0
0.3
0.6
0.9
-0.3
-0.6
-0.9
S
First component
Figure 20: Diagram of the physical factors variables in the savannah and rocky shrubalnds, showing eigenvectors values along the first and the second component axis, and distinct variables distribution
40
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
1.12.2.
Relationship vegetation degradation and human and physical factors
The results of the correlation analysis, obtained from linear regression, for investigation of the relationship among vegetation degradation scores and human and physical factors, in the forest and scrub areas,
are shown in the Table 13. The human factors, distance to village/city/rural settlements, distance to roads
and distance to mining sites presented a negative correlation to vegetation degradation levels. In the case
of the physical factors, geology and distance to drainage showed a positive correlation to vegetation degradation. The physical factor slope presented a negative correlation coefficient (R2=-0.223; p= 0.011).
That factor was the only one that showed a significant correlation to vegetation degradation in the forest
and scrub areas (Figure 21).
Table 13: Correlation coefficients among human and physical factors and vegetation degradation
scores in the forest and scrub areas (bold entry indicate result significant at ∞ = 0.05)
Dependent
Variable
Forest and
scrub
Independent Variables
Human factors
Physical factors
Distance to Distance
Distance
Slope
Geology
Distance to
village/city/ to
the to mining %
Classes
drainage
settlements roads
sites
Vegetation
degradation
scores
-0.086
-0.001
-0.021
-0.223
0.072
0.100
80
Vegetation degradation scores
60
40
20
0
-20
-40
-60
Rsq = 0.2226
0
10
20
30
40
50
60
70
Slope (%)
Figure 21: Scatter plot and fitted line showing the relationship between vegetation degradation
scores and slope percentage in forest areas
The correlation analysis results for the savannah and rocky shrublands formations (Table 14), showed that
the human factors distance to agricultural areas, distance to roads, distance to mining sites and distance to
tourist sites were negatively correlated to vegetation degradation variations in that areas. The physical
41
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
factors slope, geology and distance to drainage were found negatively correlated to vegetation degradation. The human factor distance to tourist sites was the one presented a significant correlation (R2=0.250; p=0.029) to vegetation degradation (Figure 22).
Table 14: Correlation coefficients among human and physical factors and vegetation degradation
scores in the savannah and rocky shrublands (bold entry indicate result significant at ∞ = 0.05)
Dependent
Variable
Savannah
Distance to
and Rocky Agriculshrublands tural areas
Vegetation
-0.069
degradation
scores
Independent Variables
Human factors
Physical factors
Distance
Distance
Distance Slope Geology Distance to
to
the to mining to tour- %
drainage
roads
sites
ist sites
-0.137
-0.056
-0.250
-0.181
-0.061
-0.001
120
Vegetation degradation scores
100
80
60
40
20
0
-20
-2000
Rsq = 0.2505
0
2000
4000
6000
8000
10000
Distance to tourist sites (m)
Figure 22: Scatter plot and fitted line showing the relationship between vegetation degradation
scores and distance to tourist sites in the savannah and rocky shrublands formations
42
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
1.13.
Assessing areas at risk of vegetation degradation
The spatial prediction of areas at risk of vegetation degradation was derived from regression analysis. The
input variables of the model comprehended those that showed a significant relationship with vegetation
degradation. For the forest and scrub areas, the variable slope was the one included and the model generated responded for 19% of the variability of vegetation degradation (adjusted R2 = 0.193). In the case of
savannah and rocky shrublands formations the variable distance to tourist sites was selected and the
model explained 20% (adjusted R2 = 0.206) of the variability of vegetation degradation in that areas.
The regression functions used for the prediction were:
Y= bo - b1x
Y – response variable
x- explanatory variable
bo - intercept
b1 – slope parameter
Forest and scrub
Y= 44.4 – 1.08 *x1
Y- Vegetation degradation
x1 – slope
Savannah and Rocky shrublands
Y=60.3 43
– 0.00478 * x2
Y- Vegetation degradation
x2 – distance to tourist sites
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
The spatial prediction of areas at risk of degradation was performed in the GIS environment. The definition of risk classes was based on the pattern of the distribution of the plots sampled in the ground in relation to the factors slope (forest) and distance to tourist sites (savannah and rocky shrublands). The distribution of vegetation degradation classes in relation to the significant factors considered is shown in Figures 23 and 24. Although there was not a very clear pattern, the higher concentration of extremely degraded areas, low degraded and not degraded areas in the ground provided an orientation for the determination of classes of high, moderate, low and not risk. The extremely degraded areas, which are on the map
of distribution of vegetation degradation (Map 4), were removed from the map of areas at risk for forest
degradation. For the savannah and rocky shrublands, the whole area covered by this vegetation type was
considered (Map 5), since the map of vegetation degradation distribution could not be obtained for those
formations. The input maps used for generation of the maps of areas at risk of vegetation degradation area
shown in Appendix 12.
It is important to highlight that the prediction of areas at risk of vegetation degradation is based only in
the factor slope and distance to tourist sites. Moreover, the model validation could not be performed,
since all the training data set was used for model calibration.
Figure 23: Distribution of vegetation degradation
classes
(% of occurrence) in the different slope classes, in forest
Areas
Figure 24: Distribution of vegetation degradation
classes (% of occurrence) in different distance to
tourist sites classes, in the savannah and rocky
shrublands formations
44
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Map 4: Forest areas at risk of vegetation degradation, based on the physical factor slope
Map 5: Savannah and rocky shrublands areas at risk of vegetation degradation, based on the human factor distance to tourist sites
45
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
46
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
DISCUSSION
1.14.
Land cover and vegetation characterization
The accuracy assessment is a fundamental part of the process of image classification because it gives an
idea of the validity of the results. The total number of sample plots collected can influence the accuracy
(Jensen, 1996). Congalton (1991) suggested a minimum of 50 samples to be collected for each land cover
class. In the present research, constraints of time and accessibility to the target areas limited the number
of sample plots to a much lower value than the proposed one. However, the overall classification accuracy obtained in the present study was 82%, which is slightly lower that proposed by Anderson (1976): 85
to 90% for land use and land cover assessment for planning and management purposes. The generalization of classes certainly contributed to improvements in the accuracy. Moreover, results of 100% in the
user accuracy for the classes Eucaliptus plantation, rocky shrublands and pastures, with use of only 6, 8
and 14 sample plots respectively, can be seen as too optimistic and susceptible of errors. The fact that the
use of few sample sites to characterize a study area can be a major source of error in remote sensing investigations is referred to by Brogaard & Ólafsdóttir (1997). The authors recommended a sample size larger than 30 sample plots per class aiming to reduce errors. Thus, the judgment of the accuracy assessment
results has to be considered together with constraints of sample size, when using the information for decision making.
1.15.
Variations and distribution of vegetation degradation
The results of categorization of vegetation in degradation classes showed that the majority of sampled
sites were found degraded. The findings have certainly relation with the large amount of damaging activities signs found in the sampled areas. Different authors refer to the contribution of activities such as grazing, cutting and fire to processes of vegetation degradation (Kakembo 2001; Dongmo 1998; TCM 1998;
Grégroire et al 1998; Hofstad 1997; World Resources Institute 1996; De Pietri 1995; Kumar & Bhandari
1992; De Pietri 1992; Talbot 1986). Additionally, the absence of efficient fencing system as verified in
the investigated areas, can bring about increase in grazing pressure and subsequent degradation processes.
Kumar & Bhandari (1992) found higher degradation in unfenced areas in relation to the fenced ones, in a
study of the impact of protection of areas from free grazing in sand dune vegetation.
The forest areas presented higher levels of degradation while undisturbed and low degraded situations
were found only in the savannah and rocky shrublands. The large availability of resources, especially
wood for fuelwood and building materials in the forest areas (Arnold & Dewees 1997), can be a source of
major attraction for damaging activities.
In the savannah areas of the EPA the trees are short and occur in low proportion, sparsely distributed
through the grass layer, and consequently they do not have the potential for cutting and charcoal production activities. The latter activity is characterized as the highest important disturbance pressure in most of
the savannah areas in Brazil (Mistry 2000). Disturbances caused by fire, although can occur in savannah
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
areas in cases of accidental or criminal intensive burning, are not a major problem when that factor is kept
in periodical lower frequencies (Coutinho 1990). Since fire is an old component of savannah ecosystems
the vegetation has developed resistance and dependency on this factor (Mistry 2000; Coutinho 1990;
Rizzini 1979). Among the beneficial effects of fire one can cite the stimulation of germination, resprouting, flowering, fruiting and nutrient recycling acceleration (Coutinho 1990).
The rocky shrublands are attractive especially for mining activities, but the impacts, although large, are
restricted to the mining location. Similarly, the impacts of tourist activity on the rocky shrublands are limited to those areas close to waterfalls and cities.
The use of ecological indicators provided an assessment of the vegetation conditions in the area. The indicator invasive species presented the highest weight in the definition of the degradation levels in forest
areas, and showed positively correlated to the process. The increase of invasive species and introduced
grasses in degraded areas is considered important by different authors (Joshi 2001; De Pietri 1991; TCM
1998; World Resources Institute, 1996).
The understory cover and canopy cover presented similar levels of influence in the weighting process and
showed negatively correlated to the vegetation degradation. According to De Pietri (1991) the decrease of
shade tolerant species in the understory is one of characteristics of degradation in vegetation. Other modifications in the understory, as a result of degradation by grazing activities is the reduction of palatable
plants and seedlings (TCM 1998; Hofstad 1997; Dongmo 1994). The thinning of the forest canopy cover
was pointed out by De Pietri (1991), as a marked tendency in the vegetation degradation process. In studies of forest degradation, areas with lower canopy cover (under 20%) are referred as indicating degradation processes (Hargyono, 1993). In the areas under study the scrub areas presented the lowest canopy
cover. According to Pedralli et al (1997) the scrub formations with dominance of Vanillosmopsis
erythropappa is a characterisitc secondary succession in the Ouro Preto region, that develops after human
disturbances over forest areas. The number of individuals of the species reduces gradually with the development of the forest into more advanced succession stages.
For the savannah and rocky shrublands formations the indicators bare soil cover and invasive species
showed higher influence in the vegetation degradation levels definition. Both variables were found positively correlated to degradation what agrees with Dongmo (1994) and De Pietri (1991). The indicator
dead shrub percentage had a lower contribution and showed positively correlated to vegetation degradation, what is corroborated by TCM 1998.
.
The attempt of mapping spatial distribution of vegetation degradation using the Landsat TM image 2000
presented constraints, represented by the low number of undisturbed situations among the sample plots.
Vegetation degradation is probably visualized and detected better through monitoring and spatio-temporal
image analysis. The methodology developed by Arquero et al (2001), for example, for identification of
natural degraded areas using dispersion diagrams of the spectral reflectance of features, relies on monitoring of the area under study, and knowledge of the previous state of the actual degraded areas. Other studies using multi-spectral satellite data were undertaken according to multi-temporal map classification
(Tanser & Palmer 2000) or in arid landscapes, where a large amount of areas denuded of vegetation was
found (Viljoen et. al. 1993).
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Other limitations to the spatial distribution mapping of variations in vegetation degradation the EPA Cachoeira das Andorinhas was related to the mixing of spectral characteristics among different classes. In
the forest areas, the variations in canopy cover were the best indicators that could be detected from satellite sensors and allow the mapping of the vegetation degradation classes. However, only the scrub areas,
characterized as extremely degraded, presented a stronger canopy cover differentiation in relation to the
others, having potential for mapping. In the savannah and rocky shrublands, the indicator bare soil cover
could be the one best suited for detection from satellite sensors, but only three sample plots presented a
higher amount of bare soil, enough for differentiation.
1.16.
Vegetation degradation distribution in response to human and physical
factors
The results of correlation analysis for the forest areas showed that slope is a significant physical factor
influencing the vegetation degradation distribution in the EPA Cachoeira das Andorinhas. The negative
association of this factor with forest degradation agrees with Mather (1992). This author argues that slope
is a proximate factor that can increase accessibility of humans to forest areas. In the study area, activities
of cutting and grazing might be hindered by the slope steepness, with presence of higher degradation levels in the areas with lower slopes.
In the savannah and rocky shrublands formations the human factor ‘distance to tourist sites’ presented a
significant negative correlation with vegetation degradation. The tourist visitation is higher in the southern part of the EPA, where Ouro Preto and the Andorinhas waterfall are located. In protected areas in
Costa Rica and Belize, Farrell & Marion (2001) also found that intense tourist visitation can degrade
natural resources and contribute to vegetation damage and loss. The authors argued that successful ecotourism and protected area management needs effective management of natural areas for visitor enjoyment
and resource protection. There is not yet a planned ecotourism in the study area, with definition of special
trails and recreation sites, what might worsen the situation. Marks of garbage (cans, plastics, etc) generated by the activity could be found in the areas sampled. The rocky shrublands in the south portion of the
area are the most jeopardized vegetation type by tourist activities. The savannah areas in the north are
situated farther from the tourist sites and have been less affected by the activities. An important consideration to be made is that among the tourist sites, the most populated areas of the EPA were included
(Ouro Preto neighborhoods and São Bartolomeu), what may have contributed for the findings of significant relationship between vegetation degradation and tourist sites.
The human factor ‘distance to roads network’ did not present the expected significant negative relationship with vegetation degradation levels in the different vegetation types of the area. Roads network are
equivalent to increase accessibility and human activities in the natural vegetation areas bringing about,
among others: introduction of exotic species, enhancement of dispersal of particular species, changes in
the composition of vegetation and chronic disturbance due to human activity and traffic (Saunders et al
2001). The EPA presents a considerably dense road network, but there is a higher concentration of roads
and trails in the portions south and east of the area. According to Saunders et al (2001) the influence of
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
roads in the landscape change structure, for example, is more evident when the spatial distribution of
roads is regular across the extent of the study area, and the resolution of the analysis is relatively broad.
The fact that only a few spatially explicit factors were found significantly influencing the vegetation degradation levels in the study area may indicate that other factors are involved. Kakembo (2001) found land
management practices that vary with land-tenure systems, as the main controlling factor to the spatial
variations in vegetation degradation in South Africa. In the EPA Cachoeira das Andorinhas there are
some indications that land ownership might be a factor influencing vegetation degradation. In the north of
the area, conflicts of land ownership were reported during the interviews. The enterprise VDL Siderurgic
claims the ownership of 5800 ha in the EPA, but small farmers plead the rights over some properties. According to the farmers, the land, where they now live, was a donation made by their employer (previous
owner - Queiroz Junior Siderurgic). Furthermore, the long time that they have been settled in the area
could give them the rights. The VDL Siderurgic has maintained guards inside the properties to restrict the
exploitation of natural resources, specially the cutting of trees (Vannilosmopsis erythropappa). The control over some areas might be affecting the use and level of human disturbances in relation to the
neighboring areas. Similarly, in the south of the area, close to Ouro Preto vicinity a patch of forest area
(Mata da Brígida) belongs to the UFOP (Federal University of Ouro Preto) that keeps the fenced area as a
source of academic research. However, further research is needed to evaluate accurately the influence of
land ownership in the vegetation degradation processes in the EPA Cachoeira das Andorinhas.
The low number of sample plots, especially in the savannah and rocky shrublands formation may have
contributed to the low correlation coefficient and significance of the human and physical factors investigated.
Assessing the areas at risk of vegetation degradation
In the present research, the first step of the assessment of areas at risk of vegetation degradation was the
verification of what and in which direction human and physical factors were influencing the spatial distribution of variations in vegetation degradation in the area. Regression analysis was performed and the significant variables were used as input in the spatial model, in the GIS environment.
The generated output map of areas at risk of vegetation degradation in the forest areas was based on the
physical factor slope. In the savannah and rocky shrublands formations the significant factor distance to
the tourist sites was used. The expected validation of the model could not be performed due to the use of
all sample units for model calibration. The evaluation or validation of a model is essential for determining
how accurate the predictions are (Guisan & Zimmerman 2000). A rough idea of how good the variables
explain the spatial variations of vegetation degradation in the area can be given by the resulted adjusted
correlation coefficient. The variable slope responded for 19% of the vegetation degradation variability in
the forest areas, and distance to tourist sites explained 20% of the variability of vegetation degradation in
the savannah and rocky shrublands formations. Although the assessment of areas at risk can provide information to support decision making and management improvement, the low participation of the considered variables in the overall process has to be taken into consideration when using the information.
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5. CONCLUSION AND RECCCOMENDATIONS
The study has presented an assessment of the spatial distribution of vegetation degradation in the Environmental Protection Area Cachoeira das Andorinhas and its relationship with human and physical factors. Most of the factors investigated did not present a significant correlation with the variations in vegetation degradation. However, vegetation degradation in the area was found significantly negatively influenced by the factor slope, in the forest areas, and significantly negatively associated to distance to the
tourist sites, in the savannah and rocky shrublands formations. Those factors can facilitate accessibility
and the development of human damaging activities in the site.
The factors slope and distance to tourist sites could be used as input variables to assess the areas at risk of
vegetation degradation in the EPA. However, the use of the information for conservation management
strategies establishment has to take into consideration the low participation of the input variables in the
overall vegetation degradation variability in the area.
The combination of Remote Sensing, GIS and ground truth data provided means for the assessment of the
spatial distribution of the extremely degraded forest areas, but not for the whole vegetation degradation
variations. Landsat TM imagery probably provides better results through spatio - temporal investigations
of vegetation degradation, where the previous undisturbed state is well known. The generated map of spatial distribution of extremely degraded forest areas (scrub) can provide valuable information for management improvements and regeneration strategies in the area.
The importance of the vegetation of the EPA for watershed protection, representation of remnants of the
highly threatened Atlantic Forest in Minas Gerais state, and the intense fragmentation of the vegetation in
surrounding areas, bring about concerns about the consequences of persistence of degradation processes
in a chronic manner. Effective interventions for land use development and biodiversity protection are
needed, but depend on the fully involvement of local communities and stakeholders in the decisions for
management strategy definition.
Some recommendations for further research and management of the area are given following, based on
the present study findings:
- Investigation of vegetation degradation through permanent plots to track better the process dynamics
- Investigation of the influence of other factors, such as, land ownership in the vegetation degradation
process
- Investigation of intensity of damaging activities in the vegetation areas
- Establishment of remote sensing monitoring system to track undesirable changes in the vegetation, in
the spatio-temporal context
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
-
Elaboration of ecotourism plan that include the local communities and orientates visitors
Elaboration of general forest management plan for the whole area
Support to the communities for the establishment of effective fencing system and appropriate pastures management, that exclude the grazing of livestock in the natural vegetation areas, specially in
the lower slopes
ABSTRACT
Most of the investigation of factors influencing vegetation degradation in the spatial context has been directed at arid landscapes or at degradation of temperate and tropical forests.
This study examined the influence of human and physical factors in the spatial distribution of vegetation
degradation in the Environmental Protection Area Cachoeira das Andorinhas (Brazil), characterized by
subtropical moderately humid climate. The degradation affects forest, savannah and rocky shrublands
formations.
Remote Sensing, Geographic Information Systems (GIS) and statistical analysis techniques were used
together with field data collection. Landsat TM image, topographic map, DEM and secondary data were
used for generation of maps of the human and physical factors examined. Those factors comprised: distance to the roads, distance to rural settlements/village/city, distance to tourist sites, distance to mining
sites, distance to agricultural areas, distance to the drainage, slope and geology. The diagnosis of vegetation degradation variations was made with utilization of five ecological indicators: invasive species cover,
understory cover, canopy cover, bare soil cover and dead shrub percentage. The total of 47 sample plots
was classified according to vegetation degradation variations. Principal Component Analysis was performed for generation of scores that represented numerically the levels of vegetation degradation. Regression analysis was used to investigate the relationship between vegetation degradation and human and
physical factors, and to select significant variables, used in the assessment of areas at risk of vegetation
degradation.
The factors slope and distance to tourist sites presented significantly negatively correlated to the vegetation degradation in forest and savannah /rocky shrublands formations, respectively. The assessment of
areas at risk of vegetation degradation was based on those factors that represented 20% and 19% respectively of the variability of the vegetation degradation variations in the area. The spatial variations of vegetation degradation were mapped for the extremely degraded forest areas (scrub).
The factors slope and distance to tourist sites can enhance accessibility of humans and livestock to natural
vegetation areas which may increase intensity of damaging activities in areas of lower slope and shorter
distance to tourist sites. The low significance of the factors used to assess areas at risk of vegetation degradation suggested limitations for further use of the information. The possibility of mapping spatial distribution of vegetation degradation only for extremely degraded areas suggested limitations of using remote
sensing techniques to detect the degradation process when considering one single point in time, few undisturbed situations and lower levels of degradation.
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
The information can contribute to improvements in conservation management strategies in the protection
area, but the low influence of the factors in the overall vegetation degradation process has to be considered.
The low number of not degraded situations among the sampled units presented as a constraint for vegetation degradation mapping, that is better detected through monitoring. The assessment of areas at risk of
vegetation degradation presented constraints of low significance of the factors involved.
This author argues that slope is a proximate factor that can increase accessibility of humans to forest areas. In the study area, activities of cutting and grazing might be hindered by the slope steepness, with
presence of higher degradation levels in the areas with lower slopes.
The influence of the factors slope and distance to tourist sites can be seen as an expression of the underlying inappropriate use and management of the vegetation resources in the Environmental Protection Area
Cachoeira das Andorinhas. Those factors can facilitate accessibility and the development of human damage activities in the site.
Some recommendations for management are made following, based on the research findings and interviews undertaken:
Reccomm: futher research
Investigation of other factors, land ownership
Research using permanent plots for better investigstion of the process
Intensity of damage in different areas
Monitoring investigation of changes in a spatio-temporal context
Implications for management
People involvement, area of sutainable use: high proportion of damge activites
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
The findings of vegetation degradation reflected in the increase of invasive species, understory impoverishment, canopy cover decrease, bare soil cover increase and increase of dead shrubs has an indication of
vulnerability and risk of the ecosystems found inside the protection area. In the forest areas, 36% of the
investigated sites presented moderately degraded, 36% highly degraded and 28% extremely degraded. In
the savannah and rocky shrublands formations, 37% of the examined areas were found low degraded,
37% moderately degraded, 6% highly degraded, 10% extremely degraded and 10% not degraded.
-
Elaboration of zoning and management plan for the area with establishment of priority areas for conservation, management and use of natural resources
Elaboration of general forest management plan for the whole area
Elaboration of ecotourism plan that contemplates the local communities and orientates visitors
Establishment of remote sensing monitoring system to track undesirable changes in the environment
Improvement in the involvement of local communities, including awareness about implications of the
fact that the area is an EPA and education concerning fauna and flora conservation
Support to the communities for the establishment of effective fencing system and appropriate pastures management, that exclude the grazing of livestock in the natural vegetation areas
Investigation and solution of land ownership conflicts
Support to the local communities regarding agriculture assistance, establishment of cooperatives for
small scale products sell and alternative activities for income generation
Support and orientation to miners that has the quartzite exploitation as a source of income, regarding
licensing procedures and recuperation plan
can be seen as an expression of the underlying inappropriate use and management of the vegetation resources in the Environmental Protection Area Cachoeira das Andorinhas, since they
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ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
The assessment of areas at risk using regression analysis and GIS modeling provided an indication of areas of higher vulnerability to damage activities. The use of
of use of integrated capabilities of
There are variations in the levels of vegetation degradation, with forest areas presenting higher levels of
degradation in realtion to this and that
Remote sensing allowed this and this but not the mapping of the overall, with only scrub areas mapped
The areas were assed for risk in relation to factors this and this, but represented low variabilita
The use of integrated capabilities of Remote Sensing, GIS and ground truth data allowed the classification
of the land cover and vegetation of the study area, tested in a Confusion Matrix. According to Johnston
(1998) satellite imagery has many advantages as a source of GIS data: it can be obtained in digital form;
provides frequent recurrence of coverage; allows cover of an extensive area and efficient image analysis.
The author pointed out that Landsat Thematic Mapper imagery, resolution 30m, offers desirable characteristics for land cover, land use and ecological applications.
According to Johnson (1988) risk can be defined as the probability of occurrence of a specific undesirable
event. Due to the fact that nature is too complex and heterogeneous to be accurately predicted in every
aspect of time and space (Guisan and Zimmerman 2000), the selection of relevant measurable variables
that reflects the ecosystem state is fundamental in model simulation (Johnson 1988).
The predictive geographical modeling in ecology is generally based on hypothesis on how environmental
factors influences the distribution of communities (Guisan & Zimmermann 2000).
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
the situation as it of the question that if the degradation persist in chronic state the area can become as
fragmented as the areas in the surroundings.
The Environmental Area cachoeria das Andorinhas is a conservation category of sustainable use th
repectively in the forest and savannah/rocky shrublands formation. Those factors can been seen of an
expression of human activities in the area, through cutting, grazing, mining and fire activities.
The high incidence of degradation levels in the forest, savannah and rocky shrublands found shows the
vulnerability of that ecosystems and the necessity of establishment of management strategies to meliorate
the situation presence of signs of damage activities and quantification of ecological indicators provided
the inidcation that the vegetation in the area is target of degradation processes.
Moreover, Coutinho (1990) and Mistry (2000) presented that presence of invasive species, principally
Melinis minutiflora is an important threat for the native flora of the brazilian savannah, reducing biodiversity of the herbaceous flora, increasing fire temperature and greater loss in nutrients. In the degraded
savannah areas of the EPA Cachoeira das Andorinhas, that invasive species was also found.
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
The fact that activities such as grazing, cutting and fire contribute to processes of vegetation degradation
is referred by different authors
The results of the categorization of the 28 sample plots of the forest and scrub areas into vegetation degradation conditions are presented in the Table 7. The criteria, threshold values and original data used are
shown in Appendices 5, 6 and 7. From the total areas sampled, 8 cases were classified as extremely degraded (class four), 10 as highly degraded (class three), and 10 cases were found moderately degraded
(class two). The forest intermediate stage presented 60% of the sample plots classified as highly degraded
and 40% as moderately degraded. The forest advanced stage, otherwise, comprehended 40% of sample
units classified as highly degraded and 60% as moderately degraded. The scrub areas were all classified
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as extremely degraded. For the savannah and rocky shrublands formations (Table 8), in the totality of 19
sample plots, 2 cases were found extremely degraded (class four), 1 case highly degraded (class three), 7
moderately degraded (class two), 7 low degraded (class one) and 1 not degraded (class zero). The savannah had 9% of the sample plots classified as highly degraded, 46% as moderately degraded, 36% as low
degraded and 9% as not degraded. The rocky shrublands comprehended 25% classified as extremely degraded, 25% moderately degraded, 38% as low degraded and 12% as not degraded.
The generation of maps of land cover, vegetation, and area at risk of vegetation degradation can bring
about applications for management improvements in the area.
Consideri
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Considering the area under study, the closeness to Ouro Preto bring about other damage activities, including the quartzite exploitation in a river bed close to Cachoeira das Andorinhas waterfall and free grazing
activities.
research scope. Short term perspective what is more visible: bare soil cover, inv speceis and decrease of
healthy shrubs .
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
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6.
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ACKNOWLEDGEMENTS
3.3- Vegetation degradation distribution in response to human and physical factors
3.4- Assessing areas at risk of vegetation degradation
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7. References
Andrade, J.A. 2000. Diagnostico Geoambiental da Cabeceira do Rio das Velhas – APA Cachoeira das
Andorinhas, Ouro Preto, Minas Gerais. Dissertacao de Mestrado. Universidade Federal de Ouro Preto,
MG. Brasil.
Van Duren, I. 2001. Biodiversity. Elective 9. ITC.
IEF.1994. Processo no. 2394. Plano de Manejo Florestal Simplificado Simultaneo. Fazenda Cardoso
(Evanir Alves Pinto), Ouro Preto, MG.
Lorenzi, H. 1992. Arvores Brasileiras – manual de Identificacao e cultivo de plantas arboreas nativas do
Brasil. Nova Odessa, SP: Edotora Plantarum.
IBGE, 1991. Censo Demografico. Resultados do universo relativos as caracteristicas da populacao e dos
domicilios. Numero 18 – Minas Gerais.
IBGE ( Fundacao Instituto Brasileiro de Geografia e Estatistica, censo Demografico, Riode janeiro,
p.1 –1037, IbGE/CDDI. Depto de Documentacao e Bibliotec – R.J. IBGE/93-20
IBGE 2001Sinopse preliminar do Censo demografico 2000 – volume 7 –
1. brasil – censo Demografico.1. IBGE.II. Recenseamento geral do Brasil. IBGE. CDDI. DEPTO de
Documentacao e Biblioteca, RJ. IBGE 20001 –06-fev.
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APPENDICES
Appendix 1a: Relevee sheet for land cover and vegetation conditions assessment
Date:
Site plot location in
UTM
Sample nr.
Easting
Northing
Land form:
Flat ( )
Valley ( )
Hills ( )
Plateau ( )
( ) Presence
( ) Absence
Fences
( )yes
( )no
Map nr.
GPS- X:
Y:
Rock lithology:
Granite ( )
Quartzite ( )
Sand ( )
Other ( )
Type:
Cattle ( )
Goat ( )
Another:________
Land cover
Trees ( )
Shrubs( )
Crops ( )
Grass ( )
Water bodies ( )
Bare land ( )
Other ( )
Land use
Forest ( )
Rocky shrubl. ( )
Ecotone ( )
Pasture ( )
Road ( )
Agriculture ( )
Mining ( )
Other ( )
Crops
Plot size: ______
Ground cover %
Bare soil ____
Shrub layer ______
Grass ______
Litter ______
Lichens _______
Mosses ________
Ferns __________
Trunks_________
Branches _______
Type
Corn ( )
Citrus ( )
Fruit ( )
Horticulture ( )
Other __________
Succession stage
Forest
Scrubs– higher trees
5m ( )
Forest intermediate
stage – higher trees 12
m ( )
Forest advanced stage
higher trees >12m ( )
Terrain
Data
Livestock
Annual ( )
Perennial ( )
Vegetation Conditions
Environmental quality/
Vegetation degradation
Type:
Forest ( )
Rochy shrubl. ( )
Ecotone ( )
Other ________
Sensitive species
Count – range (poor,
fair, good, excellent)
Or-
Invasive species
Cover %
10 ( ) 60 ( )
20 ( ) 70 ( )
65
Photo nr.
Observer:
Altitude:
Slope%
Lower slope 0-5% ( )
Middle slope 5-10% ( )
High slope 10-20% ( )
Valley ( )
Presence of droppings
within 50 m
Yes / no
Presence of tracks
within 50 m
Yes / no
Soil erosion:
Gullies ( )
Rills ( )
Sheet erosion ( )
None ( )
Fire indicators:
Presence ( )
Absence ( )
Ploughing quality
Poorly plough. ( )
Neatly plough. ( )
Good plough. ( )
Contour ridges
Good ( )
Moderate ( )
Poor ( )
Species indicators of
sucession stage %
Climaxes:______________
________
___________________
___________
___________________
___________
_______________
Pioneers:_______
_______________
_______________
_______________
Canopy cover
Estimated %
10 ( )
20 ( )
Rocky shrublands,
savannahs, shrublands
Shrubs number
__________________
__________________
__________________
__________________
Dead shrubs number
__________________
__________________
__________________
Plant species present in
the:
Top canopy
_______________
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Pollution ___________
Damages ___________
Tourist sites:
Location ___________
Density_____________
Damage signs:
( ) garbage
( ) fire
( ) others
chids______________
__________
Bromeliads______
_______________
Ferns______________
____________
Lichens ________
_______________
Road network:
Location:___________
Type: car ( ) dirt ( )
Bike ( ) foot ( )
Density:___________
Damage ____________
30 ( ) 80 ( )
40 ( ) 90 ( )
50 ( ) 100 ( )
Species important
(5/10)______________
___________________
___________________
___________________
___________________
___________________
30 ( )
40 ( )
50 ( )
60 ( )
70 ( )
80 ( )
90 ( )
100 ( )
Mining sites
Damages (erosion,
fires) ___________
Road network (intense?) ___________
( ) licensed ( )not lic.
Settlement sites
People number_______
Roads yes ( ) no ( )
Waste disposal yes ( )
No ( )
Energy yes ( ) no ( )
66
_______________
_______________
_______________
Understory
__________________
__________________
__________________
______
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Appendix 1b: Relevee sheet for forest structure data collection
Date:
Sample no.
Vegetation
type:
Observer:
Point no
Distance (transect line)
DBH (≥ 10cm)
Height
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
67
Species
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
30
31
32
33
34
35
68
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Appendix 2: Map of observation points
69
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Appendix 3: List of invasive and opportunist species considered in the research
Invasive and opportunist species
Species
Family
Arundinaria effusa
Eupatorium sp
Gramineae 1 (invasive – from pasture)
Gramineae 2 ( invasive – from pasture)
Gleichenia sp
Lantana lilacina
Mellinis minutiflora
Panicum sp
Pteridium aquilinum
Rhynchospora exaltata
Solanum sp
Vernonia scorpioides
?
Asteraceae
Gramineae
Gramineae
Gleicheniacaeae
Verbenaceae
Gramineae
Gramineae
Pteridaceae
Cyperaceae
Solanaceae
Asteraceae
70
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Appendix 4: Study questionnaire used to assess the environmental problems and
3.
Study Questionnaire
Location:
Date:
Name of household head or key actor:
Household identification: (
(
(
(
(
(
) Villager
) Local Farmer
) Outsider Farmer
) Miner
)Tourist/visitor
) Other
Organization: ________________________________
1. What environmental problems in the EPA Cachoeira das Andorinhas do you consider more important?
1- Deforestation
2- Vegetation degradation
3- Soil erosion
4- Loss of wildlife
5- Water pollution in the rivers
6- Garbage
7- Waste disposal
8- Others
________________________________________________________________________
And socio-economic?
1- Lack of incentives
2- Lack of assistance for agriculture
3- Lack of alternative activities for income generation
4- Others
________________________________________________________________________
2- Thinking about the problems what measures are more urgent to be undertaken in the EPA
(indicate the more important)?
1- Implementation of ecotourism
2- More availability of land for agriculture
3- Incentives for agriculture
4 Planting of trees for income and household use decreasing use of trees in the natural vege
71
Appendix 5: Criteria and threshold values for categorization of
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
vegetation
degradation
(I – Indicator)
DEGRADATION
-ENVIRONMENTAL
PROTECTION
AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
factors
Classes of vegetation degradation
Class nr. Classes
0
Not degraded
1
Low degraded
2
Moderately degraded
3
Highly degraded
4
Extremely degraded
Ia – Invasive species cover
Invasive species cover Classes
0
0
0.1 – 25%
1
25.1 – 50%
2
50.1% - 75%
3
> 75%
4
Ib –Understory cover
Understory cover
0
0.1 – 25%
25.1 – 50%
50.1 – 75%
> 75.1%
Ic – Canopy cover
Canopy cover classes
0
0 – 25%
25.1 – 50%
50.1 – 70%
Classes
4
3
2
1
0
Id – Bare soil cover
Bare soil cover
0
0.1 – 25%
25.1 – 50%
50.1 – 75%
> 75%
Classes
4
3
2
1
Ie – Relative percentage of dead
shrubs
Dead shrubs %
Classes
0
0
0.1 – 10%
1
10.1 – 20%
2
20.1 – 30%
3
> 30%
4
Classes
0
1
2
3
4
72
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Appendix 6: List of tree species assessed in the forest areas
73
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Appendix 7: Original data of forest areas, comprising invasive species cover % (Ia), understory
cover % (Ib) and canopy cover % (Ic)
Species
Alchornea triplinervia
Amaioua guianensis
Anadenanthera colubrina
Annonaceae 1
Aspidosperma parvifolium
Aspidosperma sp
Asteraceae 1
Cabralea canjerana
Calycorectes acutatus
Casearia arborea
Casearia decandra
Casearia sylvestris
Cecropia hololeuca
Clethra scabra
Copaifera langsdorffii
Cordia sellowiana
Coutarea hexandra
Coutarea sp
Croton floribundus
Croton urucurana
Cupania vernalis
Cyathea arborea
Dalbergia villosa
Emmotum sp
Eugenia sp
Euphorbiaceae 1
Guarea guidonia
Guarea sp
Guatteria sp
Hyptidendron asperrimum
Ilex pumosa
Ilex sp
Inga marginata
Inga sp
Lamanonia ternata
Lauraceae 1
Lauraceae 2
Lauraceae 3
Leguminosae 1
Leguminosae 2
Leguminosae 3
Forest type
FIS; FAS
FIS; FAS
FIS; FAS
FAS
FIS; FAS
FIS
FAS
FAS
FIS; FAS
FAS
FAS
FAS
FIS; FAS
FIS; FAS
FIS; FAS
FIS; FAS
FAS
FAS
FIS; FAS
FAS
FIS; FAS
FIS; FAS
FIS; FAS
FIS
FAS
FAS
FAS
FIS; FAS
FAS
FIS; FAS
FIS
FIS
FIS; FAS
FAS
FAS
FIS
FIS
FAS
FIS
FAS
FAS
Licania kunthiana
Lonchocarpus sp
Luehea sp
FIS
FIS
FIS; FAS
Species
Maytenus salicifolia
Mezilaurus sp
Miconia chartacea
Miconia sp1
Miconia sp2
Miconia sp3
Mollinedia sp
Myrcia eriopus
Myrcia rostrata
Myrcia sp
Myrsinaceae
Myrtaceae 1
Myrtaceae 2
Myrtaceae 3
Myrtaceae 4
Nectandra sp1
Ocotea cf corymbosa
Ocotea odorifera
Ocotea sp1
Peltophorum sp
Pera sp
Piptocarpha sp
Pisoniela apolinari
Protium heptaphyllum
Psidium rufum
Psidium sp1
Psidium sp2
Psychotria sessilis
Rapanea umbellata
Rollinia sp
Roupala brasiliensis
Schinus terenbithifolius
Sclerolobium rugosum
Sebastiania sp
Swartzia sp1
Swartzia sp2
Tabebuia sp
Tapirira guianensis
Tibouchina candolleana
Tibouchina sp
Vanillosmopsis
erythropappa
Vernonia discolor
Vismia brasiliensis
Vochysia emarginata
74
Forest type
FIS; FAS
FAS
FAS
FAS
FIS
FIS
FAS
FIS; FAS
FIS; FAS
FAS
FAS
FIS; FAS
FIS; FAS
FIS
FAS
FIS
FIS; FAS
FAS
FIS; FAS
FIS
FIS; FAS
FIS; FAS
FAS
FIS
FIS
FIS
FIS; FAS
FIS; FAS
FIS; FAS
FAS
FIS; FAS
FIS
FIS; FAS
FAS
FIS
FIS
FAS
FAS
FIS
FIS; FAS
FIS; FAS
FIS; FAS
FIS; FAS
FIS; FAS
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Sample
Plots
1
Vegetation
types
FIS
2
FIS
40
3
4
FIS
FIS
60
60
5
FIS
30
6
FIS
5
7
8
FIS
FIS
60
40
9
FIS
20
10
FIS
30
11
12
13
FAS
FAS
FAS
60
75
10
14
FAS
10
15
FAS
5
16
FAS
10
17
FAS
50
18
FAS
20
19
FAS
40
20
FAS
20
21
22
23
ST
ST
ST
80
80
80
24
ST
55
25
ST
60
26
27
SS
SS
85
80
Ia
Ib
30
2
5
5
0
5
1
0
1
5
2
5
5
6
0
2
5
2
0
5
5
5
0
6
0
2
5
1
0
2
5
1
0
2
0
1
0
5
5
1
0
2
5
1
5
0
0
Ic
40
40
50
30
20
30
30
50
50
30
50
50
70
40
50
40
40
40
40
30
20
5
5
10
10
0
0
75
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
28
SS
80
0
0
Appendix 8: Original data of savannah and rocky shrublands areas, comprising invasive species
cover % (Ia), bare soil cover% (Ib) and dead shrubs % (Ic)
Sample
Plots
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
Vegetation
type
SA
SA
SA
SA
SA
SA
SA
SA
SA
SA
SA
RS
RS
RS
RS
RS
RS
RS
RS
Ia
Id
Ie
60
70
0
70
40
25
0
35
0
0
0
5
0
0
0
10
20
50
50
40
20
0
0
5
5
30
15
0
5
0
0
0
0
0
30
30
90
80
15
4
25
9
0
0
5
0
10
0
0
7
19
32
0
14
15
20
20
76
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Appendix 9 : Descriptive statistics
Variables
N
Minimum
Maximum
Mean
Standard
deviation
Standard
error
Median
210.2557
39.7346
161.0000
28
60
Forest and scrub
925
213.9286
Distance to village, city, rural
settlements
Distance to
tourist sites
Distance to mining sites
Distance to agricultural areas
Slope
Geology
Distance to
drainage
Vegetation degradation scores
Invasive species
cover
Understory
cover
Canopy cover
28
618
5522
2996.0714
1350.9411
255.3039
2913.5000
28
617
7175
2729.8929
1609.8224
304.2278
2339.0000
28
760
12163
5901.3214
4008.9077
757.6123
5014.5000
28
60
1631
337.3214
361.1924
68.2589
245.5000
28
28
28
3
0
17
65
1
308
28.9286
.1071
127.9643
14.4040
.3150
80.0187
2.7221
5.952E-02
15.1221
26.5000
.0000
112.0000
28
-47.22
64.91
13.0379
33.0668
6.2490
7.6855
28
5
85
45.5357
26.7824
5.0614
45.0000
28
0
60
16.4286
18.5521
3.5060
10.0000
28
0
3.5668
35.0000
Distance to
roads
Distance to village, city, rural
settlements
Distance to
tourist sites
Mining sites
distance
Distance to agricultural areas
Slope
19
60
70
31.0714
18.8737
Savannah and Rocky shrublands
1764
328.1053
466.4415
107.0090
167.0000
19
1177
6752
4006.6842
1861.7631
427.1177
4629.0000
19
76
9768
6418.0000
3387.2474
777.0878
7598.0000
19
255
6735
6735.00
1829.1771
419.6420
3670.0000
19
24
1147
419.1053
346.2586
79.4372
330.0000
19
0.3
49
18.5947
12.3188
2.8261
16.0000
Distance
toRoads
77
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Geology
Distance to
drainage
Vegetation degradation scores
Invasive species
cover
Bare soil cover
Dead shrubs %
19
19
0
53
1
413
.9474
212.8947
.2294
104.7950
5.263E-02
24.0416
1.0000
195.0000
19
0
100.82
29.6368
32.3478
7.4211
22.1270
19
0
70
22.8947
26.2634
6.0252
10.0000
19
19
0
0
90
32
18.4211
10.2632
26.9285
9.7914
6.1778
2.2463
5.0000
9.0000
Appendix 10: Kolmogorov-Smirnov Normality Test results
Variables
Forest areas
Savannah and Rocky shrublands
78
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
P- Values
Normality results
Normal distributed
Not normal distributed
Normal distributed
P-Values
<0.01
>0.15
Vegetation degradation scores
Distance to roads
> 0.15
Distance to village/city/rural
settlements
Distance to tourist sites
Distance to mining sites
Distance to agricultural areas
Slope
>0.15
Geology
>0.15
Distance to
drainage
Invasive species
cover
Understory
cover
Canopy cover
>0.15
Bare soil cover
-
Normal distributed
Normal distributed
Not normal distributed
Normal distributed
Normal distributed
Normal distributed
Normal distributed
Normal distributed
Normal distributed
-
Dead shrubs %
-
-
< 0.01
0.098
0.125
0.032
>0.15
>0.15
0.090
>0.15
79
0.037
<0.01
0.127
Normality results
Not normal distributed
Not normal distributed
Normal distributed
-
Not normal distributed
Normal distributed
Normal distributed
Normal distributed
Normal distributed
Normal distributed
Not normal distributed
-
-
-
0.027
Not normal distributed
Normal distributed
>0.15
>0.15
>0.15
>0.15
>0.15
0.013
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Appendix 10: Results of the Principal Component Analysis for independent variables selection in
the forest areas
PCA scores
First
com- Second com- Third com- Fourth com- Fifth component
ponent
ponent
ponent
ponent
Human factors eigenvalues
Eigenvalues
2.2061
1.3726
0.7664
0.3670
0.2878
Proportion
0.441
0.275
0.153
0.073
0.058
Cumulative
0.441
0.716
0.869
0.942
Human factors variables eigenvectors
-0.255
0.668
-0.406
-0.560
1.000
Distance
to
80
-0.101
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
roads
Distance to
village, city,
rural settlements
Distance to
tourist sites
Distance to
mining sites
Distance to
agricultural
areas
-0.604
0.008
0.055
0.371
-0.703
-0.202
-0.545
-0.806
0.007
0.108
-0.578
0.233
0.083
0.355
0.000
-0.442
-0.450
0.418
-0.650
0.065
Eigenvalues
Physical factors variables eigenvalues
1.1515
1.0042
0.8442
Proportion
0.384
0.335
0.281
Cumulative
0.384
0.719
1.000
Distance
drainage
Slope
Geology
to
Physical factors variables eigenvectors
0.704
-0.146
0.695
-0.709
0.039
-0.091
0.985
0.699
0.167
81
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Appendix 11: Results of the Principal Component Analysis for independent
variables selection in the savannah and rocky shrublands area
PCA scores
First
com- Second com- Third com- Fourth com- Fifth component
ponent
ponent
ponent
ponent
Human factors eigenvalues
Eigenvalues
Proportion
Cumulative
Distance to
roads
Distance to
village, city,
rural settlements
Distance to
tourist sites
Distance to
mining sites
Distance to
agricultural
areas
3.0656
0.613
0.613
0.9415
0.188
0.801
0.5309
0.106
0.908
0.3765
0.075
0.983
0.0856
0.017
1.000
Human factors variables eigenvectors
-0.311
0.822
-0.099
-0.384
-0.265
-0.547
0.061
-0.203
0.069
0.807
-0.496
-0.102
-0.379
0.611
-0.476
-0.413
-0.557
-0.131
-0.676
-0.214
-0.433
-0.020
0.888
0.134
-0.080
Eigenvalues
Proportion
Physical factors variables eigenvalues
1.3910
0.9321
0.6769
0.464
0.311
0.226
Cumulative
0.464
Distance
drainage
Slope
Geology
to
0.774
1.000
Physical factors variables eigenvectors
-0.672
-0.057
-0.739
0.473
-0.800
-0.369
0.570
0.597
-0.564
82
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Appendix 12 a – Roads map of the EPA Cachoeira das Andorinhas
83
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Appendix 12 b: Drainage map of the EPA Cachoeira das Andorinhas
84
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Appendix 12 c: Agricultural areas map of the EPA Cachoeira das Andorinhas
85
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Appendix 12 d: Geology map (generalized) of the EPA Cachoeira das Andorinhas
86
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Appendix 12 e: Slope classes map of the EPA Cachoeira das Andorinhas
87
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Appendix 12 f: Map of village, city and rural settlements of the EPA Cachoeira das
Andorinhas
Appendix 12 f: Map of tourist sites of the EPA Cachoeira das Andorinhas
88
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Appendix 12 g: Map of mining sites of the EPA Cachoeira das Andorinhas
89
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Appendix 12 f: Map of forest areas of the EPA Cachoeira das Andorinhas
90
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Appendix 12 f: Slope percentage class map of the EPA Cachoeira das Andorinhas
91
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Appendix 12 g: Map of the savannah and rocky shrublands areas of the EPA
Cachoeira das Andorinhas
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Appendix 12 h: Map of distance to tourist sites - EPA Cachoeira das Andorinhas
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Savannah and Rocky
shrublands
Grazing and/or
mining
Invasive species increase
Bare soil cover increase
Constant grazing
and/or mining
Scattered islands of
healthy vegetation
94
Shrubs mortality increase
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
0-20 20-40 40-60 >60
0-3500 3500-7000 7000-10500 >10500
The regression equation is
degrscores = 60.3 - 0.00478 touris
Predictor
Constant
touris
Coef
60.31
-0.004779
S = 28.82
SE Coef
14.47
0.002005
R-Sq = 25.0%
T
4.17
-2.38
P
0.001
0.029
R-Sq(adj) = 20.6%
Analysis of Variance
Source
Regression
Residual Error
Total
DF
1
17
18
SS
4717.6
14117.2
18834.9
MS
4717.6
830.4
F
5.68
P
0.029
The regression equation is
newscores = 44.4 - 1.08 slope
Predictor
Constant
slope
S = 29.71
Coef
44.37
-1.0832
SE Coef
12.78
0.3969
R-Sq = 22.3%
T
3.47
-2.73
P
0.002
0.011
R-Sq(adj) = 19.3%
Analysis of Variance
Source
Regression
Residual Error
Total
DF
1
26
27
SS
6572.6
22949.6
29522.2
MS
6572.6
882.7
F
7.45
P
0.011
During the variable selection procedure, the deviance reduction associated with each variable is tested for
significance at a given confidence level (usually 0.05) Zimmerman
Acrescentar gr’aficos de distribution of veg degra – slope – tourist sites
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The degradation process in the forest areas in a short-term perspective is summarized in Figure 23. The
variations of thinning in canopy cover, understory impoverishment and invasive species increase are connected to the intensity and constancy of damage activities, that although not measured in the present
Forest
complex structure
Cutting and
grazing
Canopy cover
thinning
Invasive species increase
Understory impoverishment
Pioneer species increase
Constant
cutting and
grazing
Forest simplified structure (scrub)
study, could be detected through marks, such as, livestock droppings and cutting signs. The presence of
fire signals was found in very few plots and was not considered a major problem in the forest areas. The
selective cut of trees species has leading to openings in the canopy cover, that increases growth and
dominance of invasive and opportunist species in the understory. In cases where the opening is large,
some of those species, for example Arundinaria effusa, trends to cover all over causing tree mortality and
degeneration of the forest conditions. The higher availability of light promotes the increase of pioneer
species, tolerant to that conditions. In the area, Vannilosmopsis erythropappa is one of the species that
trends to spread over the disturbed areas, being the dominant species of the scrub areas. The grazing ac97
ASSESSMENT OF HUMAN AND PHYSICAL FACTORS INFLUENCING SPATIAL DISTRIBUTION OF VEGETATION
DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
tivities, sustained by the lack of efficient fencing system with neighboring agricultural areas, intensify the
dominance of invasive species. The livestock may eliminate palatable species of the understory, including
regenerating seedlings (TCM 1988), reducing the shrubs and herbs of the understory, and promoting increase of invasive and opportunist species.
In the case of savannah and rocky shrublands formation the damage activities grazing, fire and mining are
major threats, the latter one specific for the rocky shrublands. An overview of the vegetation degradation
process in the area, in a short-term perspective, is shown in Figure 24. In the savannah areas, grazing and
fire activities has been contributing to increase in the bare soil cover and spread of invasive species. According to Coutinho (1990), one of the first savannah’s flora alteration symptoms in response to fire, in
some areas in Brazil, is the invasion by exotic grasses, such as, Melinis minutiflora. In the rocky shrublands the bare soil cover and invasive species increase are mainly linked to mining activities, established
for exploitation of the quartzite and itabirite substrates. The increase of dead shrubs and reduction of
healthy shrub layer of those formations might been pronounced by fire and grazing activities.
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Forest
complex structure
Cutting and
grazing
Canopy cover
thinning
Invasive species
increase
Understory
impoverishment
Pioneer species increase
Constant
cutting and
grazing
Forest simplified
structure (scrub)
Figure 23: General overview of the vegetation degradation process in the forest formations of the
study area, considering a short-term perspective
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Savannah and Rocky
shrublands
Grazing, fire
and/or
mining
Invasive species
increase
Bare soil cover increase
Shrubs mortality
increase
Constant g razing,
fire and/or
mining
Scattered islands of
healthy vegetation
Figure 24: General overview of the vegetation degradation process in the savannah and rocky
shrublands formations of the study area, considering a short-term perspective
The density variations of trees, shrubs and grass cover presented in the brazilian savannah vegetation has
been referred as a result of a long history of human disturbances, through activities of cattle raising, use
of fire and cutting (Rizzini, 1979). ttraction
The establishment of classes expressing the levels of vegetation degradation can bring about some subjectivity, due to the need of use of arbitrary endpoints and weights. Although expert opinion and judgement
is referred by Andreasan et al (2001) as part of the choice of relevant degraded locations and scale metrics of degradation, the use of Principal Component Analysis granted confidence to the categorization of
sample plots in low, moderately, highly, extremely and not degraded classes. The use of multivariate statistics is appropriate for cases where there is a need of integrating metrics, and the analysis provide estimation of the probability that a site has departed significantly from a not degraded to a highly degraded
state (Andreasan et al 2001). Moreover, the scores generated by the PCA made possible a numerical rep-
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
resentation of the degradation levels and influenced the decision of the direction of influence of the ecological indicators used, in relation to the vegetation degradation process.
The establishment of classes expressing the levels of vegetation degradation can bring about some subjectivity, due to the need of use of arbitrary endpoints and weights. Although expert opinion and judgement
is referred by Andreasan et al (2001) as part of the choice of relevant degraded locations and scale metrics of degradation, the use of Principal Component Analysis granted confidence to the categorization of
sample plots in low, moderately, highly, extremely and not degraded classes. The use of multivariate statistics is appropriate for cases where there is a need of integrating metrics, and the analysis provide estimation of the probability that a site has departed significantly from a not degraded to a highly degraded
state (Andreasan et al 2001). De Pietri (1995) used discriminant analysis for the categorization of degradation levels.
Moreover, the scores generated by the PCA made possible a numerical representation of the degradation
levels and influenced the decision of the direction of influence of the ecological indicators used, in relation to the vegetation degradation process.
Ecological indicators are intended to represent key information about structure, function and composition
of ecosystems (Dale & Beyeler 2001). De Pietri (1995) used five ecological indicators to diagnose vegetation degradation in three vegetation types in Argentina (tall forest, low forest and grasslands) that expressed three degradation levels: high, intermediate and moderate. In the present study invasive species
represented the highest correlation. and
The classes to be distinguished in an image classification need to have different spectral characteristics,
and reliable results depend on the establishment of distinct clusters in the feature space (Janssen 2000).
The existence of high percentage of bare soil cover is referred as a characteristic of the last stages of
vegetation degradation.
. Supervised image classification of
in: low degraded, moderately degraded, highly degraded, extremely degraded and not degraded.
The classified sample plots point map of the vegetation degradation classes was used for examination of
the spatial distribution of degraded areas.
digitizing
Most of the revegetation degradation research has been directed at arid landscapes or at degradation of
temperate and tropical forests.
Chronic human disturbances lead to vegetation degradation and subsequent reduction of desirable characteristics of areas for nature conservation.
The study provides information of factors influencing the vegetation degradation distribution in the protected area.
was significanIn the forest areas, 36% of the investigated sites presented moderately degraded, 36%
highly degraded and 28% extremely degraded. In the savannah and rocky shrublands formations, 37% of
the examined areas were found low degraded, 37% moderately degraded, 6% highly degraded, 10% extremely degraded and 10% not degraded.
The physical factor slope presented a negative correlation coefficient (-0.223). That factor was the only
one that showed a significant correlation to vegetation degradation variations in the forest and scrub areas
(Figure 21).
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digital elevation model (
Investigation of vulnerability and degradation process of the vegetation inside protected areas There is a
lack of studies of the human influence in protected areas, involving different types of vegetation. Although studies of degradation in forest areas and vegetation of arid landscapes exist, there is a lack of
studies of the phenomenon in protected areas, involving different vegetation types.
Remote sensing and Geographic Information Systems (GIS) are used coupled with field data collected.
Most of the studies examining the influence of human and physical factors in the vegetation degradation
process has been directed at arid landscapes and forest areas lack considerations of the quality and quantity of vegetation conditions.
Palo et al (1986) evidenced that a degraded forest, for example, is assumed to recover from the disturbance within a period, but if the continuous situation of stress persist it may generate a deforestation condition.
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dead shrubs, shrub layer, succession stage – literature?
diagrama of vegetation degradation process
Identified the natural forest degradation from the scrub area, because most of scrub area originally was
natural forest. Concluded that, then the decrease of natural forest while the scrub took over is indicating
forest degradation.
Degradation process is marked by a tendency to
De Pietri (1991) found three main indicators for vegetation degradation caused by cattle ranching in Argentina: key species (icluding decreasers, increasers, and invaders); vegetal cover of exotic species, relative ratio of perennial-annual species in summer, and relative cover of an specific species not used as forage and vegetal biomass.
presented some constraints. Although some of them were found in the literature, the difference in vegetation type bring about the need of different indicators. In the case of forest areas scrub are usually seen as
the most degraded areas .. succesion stage. Some subjectivity There is not standard criteria developed
canpy cover invasive species
Definition of tresholds in the area: need of knowledge of not degraded situation/ some subjectivity that
need the not degraded situation
Dale 2001
They can provide an early warning signal of changes in the environment, and they can be used to diagnose the cause of an environmental problem. The purpose influences the choice of ecological indicators.
The suite of indicators should represent key information about structure, function and composition.
Have not knowledge history of the disturbance history in the area, although have indications of disturbance
Andreasan 2001
The location of a “degraded” reference condition may be based on expert opinion combined with historical experience of drastic ecosystem changes.. Prudence would dictate that a margin of error be built into
the degraded end of the metric to deal with uncertainty. There is a need of estimation of the potential
scale of metrics, based on the history and long-term ecological research network. By having a “natural” or
“sustainable” condition at one end of the scale for each metric and a degraded condition at the other hand,
the total range of each metric can be specified.
De Pietri 1991
If natural environmental conditions such as elevation, aspect and slope are similar, variation in vegetal
communities in terms of structure and composition may be attributed mainly to different livestock management. The existence or non-existence of certain species, increase or decrease of tohers, could be used
as indicators of cattle ranching intensity.
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
Determined grazing degradation ecological indicators in Argentina, for environments of high evergreen
forest, low forest and grassland. The ecological indicators found were key species, icluding decreasers
(those that tend to disappear under livestock ranching pressure), increasers (those that increases or keep
stable frequencies) and invaders ( those species not belonging to the original vegetal community that appear in the area due to changes in micro-environmental features.; vegetal cover: exotic species relative
cover, relative ratio of perennial-annual species in summer, and relative cover of an specific species;
vegetal biomass : global vegetal biovolume and perennial cespitose, rhizomatose and stoloniferous.
De Pietri 1995
5 representative physiognomic formations or vegetation types: tall forest; low forest; grasslands.
She used five ecological indicators to diagnose the degradation state in twenty-eight sampling sites. A
grid was obtained for each indicator discriminating 3 degrees of degradation: low, intermediate and high.
The five ecological indicators: relative cover of Rumex acetosella (perennial species of no foriage value);
relative cover of annual species; total biomass; biomass of clonal species; relative cover of exotic species.
The mapping of degraded vegetation areas expected in all categories was limited to the scrub areas. The
use of remote sensing techniques for vegetation degradation detection has been made. Author used spot
multiespectral bands…… found the spectral diagrams… in both cases however the differentiation of degrade and not were permited by the monitoring or………..
In the present research the insuffient number of not degrade situation for all vegetation types…….
Landsat TM showed also application for discrimination of forest areas conditions allowing the mapping
of the scrub areas or areas of recent regeneration and succession stage. However, limitations were found
for discrimination of forest intermediate and advanced stage. This can happened because although the
structural differences exist they are subtle and the canopy cover is not very different among the two types.
Assessment of forest succession stages and stand condition is commonly made with the utilization of aerial photographs and
Landsat Thematic Mapper has been commonly used for land cover and land use purposes.
The The Landsat TM images have seven spectral bands, three in the visible spectrum, one near-infrared
band, two mid-infrared, and one termal-infrared band.
Generalization: The results for the overall accuracy, average accuracy and average reliability were found
satisfactory, but some limitations to include more classes identified in the field occurred. In the case of
forest intermediate and advanced stage, although differences in the structure were revealed the overlap in
the reflectance response limited the stratification of the forest areas. Succession stage detection and mapping for forest areas are usually identified better using other sources and techniques……………………………..
In the case of crops, limitations on the size of the crop areas and proximity to other units made unfeasible…… Savannah although the influecne of fire and human acivities can influence the variation in the
amount of trees and grasses found it seems this process is seen in a ont time scale, out of the
The decision of the direction of influence of the ecological indicators used in relation to the vegetation
degradation process was made through the use of Principal Component Analysis, that also provide the
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DEGRADATION -ENVIRONMENTAL PROTECTION AREA CACHOEIRA DAS ANDORINHAS, BRAZIL
information of how good each variable explain the process (Jongman 1995). Moreover, the scores generated by the PCA made possible a measurement of the degradation levels and. The subjectivity generated
by the weighting process was reduced with the use of the method (Kent & Coker 1992).
The use of key species and establishment of treshold values for the degradation categories depend on the
characteristics of the area under study and vegetation types involved. According to Andreasan (2001) the
choice of a relevant degraded location require judgement and expert opinion. The cited author mentioned
that the scale metrics needs a “natural” or “sustainable” condition at one end of the scale and a “degraded” condition at the other end, to specify the total range of each metric
The high occurrence of damage signs in the sample plots in forest, scrub, svannah and rocky shrublands
formations of damage activities the natural disturbances that can be also influencing the indicators are not
included. The inexistence of strong natural disturbance in the are such as geophysical eruprions , cyclonic
storms in the short time scale assuming that the highest variations in the indicators is a response of human
disturbance.assuming that even if they are taking place is in lower proportion in relation to man made
The Principal Component Analysis viabilized direction of the influence of each of the indicators in the
vegetation degradation scores and classes were
and many times have preference
The different responses given by the different vegetation types to anthropogenic disturbance
results of the categorization of the different vegetation types sampled in vegetation degradation classes
resulted in the majority of sample units classified as degraded, and only in the savannah and rocky shrublands formations the not degraded situation was detected. what can be corroborated by the large amount
of damage activities signs found in the areas sampled. Moreover, the absence of efficient fencing system
and the presence of tracks can bring about potential increase in the susceptibility of the areas for degradation.
The use of indicators for the categorization of vegetation degradation made possible a discrimination of
degradation levels in the area.
In this study some constraints were found for the establishment of threshold values regarding the degradation indicators of forest areas, since any of the investigated locations showed a not degraded or preserved
situation, bringing about some subjectivity and uncertainty for the treshold definition.
The finding of different succession stages can be associated to the land use dynamics of the area in the
past that continues in the present time. In the two of the areas sampled, old ovens for charcoal production
were found, as a testimony of the activity. According to Pedralli et al (1997) the succession of the forest
formations is mainly associated with climatic changes, geologic changes and human intervention.
Although the research on vegetation degradation processes have presented a number of related alterations
on the structure, composition and vegetation environment, not much has been done considering quantitative measurements. Among the alterations referred one has: reduction of biomass (Hargyono 1993);
change in species composition (Hargyono 1993, Kakembo 2001); reduction of vegetal cover (Kakembo
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2001); soil degradation (Dongmo 1994; Hargyono 1993); reduction of tree growth (Dongmo 1994); increase of bare soil cover (Dongmo 1994), increase of cultivated plants (Dongmo 1994); increase of weeds
and cultivated grasses (TCM 1998); elimination of seedlings (TCM 1998); decrease of palatable plants
(Dondmo 1994; Hofastad 1997).
Table 7: Human and physical factors classes (independent variables)
One
0-100m
Two
100-200m
Classses
Three
Four
200-300m
300-400m
0-1000m
1000-2000m
2000-3000m
3000-4000m
>4000m
-
0-1000m
1000-2000m
2000-3000m
3000-4000m
>4000m
-
0-250m
250-500m
500-750m
750-1000m
>1000m
-
Variables
Roads
distance
Rural settlements,
village/city
distance
Tourist/mining
sites distance
Agricultural
areas distance
Slope
Geology
Five
400-500m
Six
>500m
0-20
20-40
40-60
>60%
Rocky
Not
rocky forma(Sediment
tions
deposits)
Drainage dis- 0-100m
100-200m
200-300m
300-400m
tance
The prolonged absence of fires can contribute even to the invasion of exotic species, since the competitive force of the native species of the lower layer is diminished, by delaying nutrient cycling or by decrease in reproductive capacity
106