Israel Journal of Plant Sciences
Vol. 53
2005
pp. 155–166
An innovative contribution of landscape ecology to vegetation science
VITTORIO INGEGNOLI
Department of Biology, University of Milan, Via Celoria 26, Milan 20133, Italy
(Received 10 July 2005 and in revised form 20 January 2006)
ABSTRACT
An expansion of the foundations of the theory of landscape ecology can relocate its
different approaches in a deeper biological vision. To this purpose, I directed my
efforts towards comprehension of the landscape and of its main component—the
vegetation mosaic—as a proper biological system.
As suggested by Naveh, I have revised landscape ecology according to new scientific paradigms, ranging from the Principle of Emerging Properties to the “order
through fluctuation” processes. Considering that a landscape is much more than
a set of spatial characters, I tried to focus its ecological elements and processes,
proposing new concepts (e.g., ecocenotope, ecotissue), new functions (e.g., biological and territorial aspects of vegetation), and new applications (e.g., evaluation of
vegetation, etc.).
This improves vegetation science through (1) a critical review of the limits
of phytosociology in studying the landscape, (2) a more coherent study of both
natural and anthropogenic vegetation, (3) a better understanding of transformation
processes, (4) a confirmation of the necessity to abandon deterministic concepts
(e.g., potential vegetation), and, especially, through (5) a new capacity for landscape
vegetation diagnosis.
Keywords: vegetation science, landscape ecology, biological territorial capacity
(BTC), ecotissue, ecocenotope
INTRODUCTION
Improving landscape ecology
Today advancement in landscape ecology is particularly
difficult. This young branch of ecology needs to synthesize and advance beyond the different approaches its
founders have given to it, primarily Naveh and Lieberman (1984, 1994) and Forman (1986, 1995). Such an
effort needs to study the landscape as a living entity. The
landscape is much more than a set of spatial characters:
it is a proper level of the hierarchy of life organization.
To a certain extent, Naveh and Forman stated that the
landscape may be defined as a living system, but they
never put this crucial concept at the base of the entire
discipline of landscape ecology.
Therefore, following the definition of landscape as a
living entity, we may observe that (1) the theoretical suggestions of Naveh and Lieberman (1984, 1994) about the
importance of new scientific paradigms in landscape ecology
led to a revision of some ecological elements and even to new
concepts, and (2) practical applications result in a wider set
of methods, consistent with the theoretical principles.
One of the major consequences of widening the
foundation of landscape ecology involves vegetation
science. The main component of a landscape is vegetation, the most important controller of the flux of energy
and matter. Vegetation communities usually form the
main mosaic of the landscape.
E-mail: [email protected]
© 2005 Science From Israel / LPPLtd., Jerusalem
156
Limits of phytosociology
At present, vegetation is defined as a set of living
plant individuals, growing in a certain site in their
natural disposition (Westhoff, 1970). In Europe, the
study of vegetation is mainly founded on phytosociology (Braun-Blanquet, 1928) and (for the landscape) on
geosynphytosociology (Biondi, 1996). But, beginning
with Naveh and Lieberman (1984), many scientists
realized the inadequacy of phytosociology in studying
landscape. The principal weaknesses of phytosociology
include the following points:
1. After about 80 years of investigations there was no
true innovation in the method of phytosociology.
Thus phytosociological results became more and
more incompatible with modern developments of
science (Pignatti et al., 2002). Indeed, this line of
investigation concentrated mostly on description of
communities.
2. It is impossible to properly show the order existing
in a vegetation community only through a floristic
description (e.g., phytosociologic tables, Pignatti
et al., 1998). On the other hand, if the shorter algorithmic description of a system coincides with the
description of the entire system, the system has to be
classified as a chaotic one (Pignatti et al., 1998). But
vegetation is not a chaotic system!
3. Classic phytosociology describes a typology of an
idealized “natural” assemblage of plants rather than
a study of vegetation in its full reality. It does not
consider the coevolution and the interaction of vegetation with man and the resulting new coenosis of
anthropogenic vegetation.
4. Until now, even in the representation of the ecological space, it has not been considered that an association must have an information content that is greater
than the sum of the information acquired by the
component species. This is due to the Principle of
Emergent Properties (Odum, 1989), which allows
a vegetation coenosis to become an attractor in its
context (the landscape), where it evolves and has to
sustain a role (Ingegnoli, 2002).
Thus phytosociology gives insufficient information
for studying a complex living system like a landscape.
For this purpose the contribution of landscape ecology
to vegetation science is needed. This may be the main
reason why Zev Naveh (personal communication) was
the first to request that I write a scientific text on landscape ecology, (Ingegnoli, 2002).
In this paper I present a brief synthesis of the new
paradigms expanding the theoretical foundation of landscape ecology, as well as some of the methods available
Israel Journal of Plant Sciences 53
2005
in studying vegetation. Two examples of natural and
human environments are presented: (1) the vegetation
of the Venice lagoon, and (2) the forested landscape unit
of the Lavazé Pass (Trentino–AltoAdige).
NEW PARADIGMS AND NEW CONCEPTS
Hierarchic levels of life and their characters
Organisms or very complex self-organizing systems
need to exchange material and energy with the environment. They are able to perceive and process information, to transform and reproduce themselves, to have
their history, and to participate in evolution. Life cannot
exist without the presence of its environment. Life and
its environment are a unique system, because the conditions allowing life are necessary both inside and outside
an adapted distinguishable entity, like an organism. That
is why the concept of life is not limited to a single organism or to a group of species, and why we describe life
organization in hierarchic levels. The landscape is one
of these levels.
Concerning this argument there is still some confusion. Organism and population generally correspond to
quite definite ranges of scale, if we consider their vital
space per individual and their minimum habitat, respectively. The upper part of the “biological spectrum”
(sensu Odum, 1971) also presents a quite definite range
of scale corresponding to ecoregions and ecosphere.
Problems arise in the middle part of the biological
spectrum, concerning communities, ecosystems, and
landscapes. For many scientists these are usable levels
at almost any scale (Allen and Hoekstra, 1992; Wiens
and Moss, 1999), or at least they occupy the same wide
range of scales. This is in contrast with the Principle
of Emerging Properties, which affirms that the whole
is greater than the sum of its components. Philosophically this was expressed by the epistemological school
of Gestalt (i.e., perception of the form; Lorenz, 1978;
Naveh and Lieberman, 1984). The differences among
communities, ecosystems, and landscapes seem to be
mainly in criteria of observation.
There are three parallel hierarchies (Ingegnoli and
Giglio, 2005), based on the biotic, on the environmental,
and on the ecological (integrated) criterion. The last one
is able to integrate the first two, since any ecological
system must include both a biological element and its
environment. Therefore, it seems probable that we have
to consider two hierarchic levels in the middle biological spectrum: (1) the ecological system, composed of
the community (biotic view), the ecosystem (functional
view), and the microchore (i.e., the spatial contiguity characters, sensu Zonneveld, 1995), which we will
name ecocoenotope, and (2) the landscape, formed by
157
a system of interacting ecocoenotopes. Consequently,
a landscape can be defined as a system of intertwining
and coevolving natural and human ecocoenotopes repeated in a characteristic way over the land.
No doubt some of the characters of community and
ecosystem are available also at landscape level, and
that the inverse is also true. Only reductionism pretends
to separate all the characters related to each level. In
contrast, we can note that each biological level presents
unique characters and exportable characteristics. For
example, processes allowing the definition of life are
exportable characteristics: each specific biological level
expresses this process in a unique way, depending on its
scale, its structure, its functions, and its amount of infor-
mation. Each system that presents unique characteristics
is an entity. We can find properties uniquely characterizing cell, organism, population, ecocoenotope, landscape, ecoregion, and ecosphere. That is why we cannot
describe the behavior of a landscape merely by scaling
up an ecological system of communities (Fig. 1).
The landscape level and its main structure
To study the behavior of a landscape it is useful to focus
on the main landscape apparatuses. The definition of
landscape apparatus (Ingegnoli, 2002) concerns functional systems of “tesserae” and/or ecotopes that form
specific configurations in the complex mosaic (i.e.,
ecotissue) of a landscape. But how can we define a tes-
Fig. 1. Flow diagram representing (above) a plant community (i.e., association) according to Pignatti (1996). Note the two main
complementary cycles: integration of spatial niches and formation of vegetation layers and humus. Below, the representation of
a system of plant communities (Ingegnoli, 1997), the main difference with that above being the cycle related to the transformation of the ecotissue.
Ingegnoli / Landscape ecology’s contribution to vegetation science
158
sera and an ecotope in this new perspective? A tessera
is the smallest homogeneous unit visible at the spatial
scale of a landscape, multifunctional but tridimensional.
It corresponds to the old definition of ecotope (as the
sum of physiotope and biotope) and it may represent the
hierarchical level of ecocoenotope.
In contrast, an ecotope is the smallest multidimensional unitary element that presents all the structural
and functional characters of the concerned landscape. It
is the minimum system of interdependent tesserae (Ingegnoli, 2002). A landscape subsystem formed by a set
of tesserae of the same landscape function (e.g., protection) can be considered a landscape apparatus.
A primary well-known landscape function is represented by the survey of human habitat (HH) versus
natural and semi-natural habitat (NH). The HH can
be defined as the whole area in which human populations live or manage permanently, limiting or strongly
influencing the self-regulation capability of natural
systems. Self-regulating and near-natural ecosystems
(i.e., almost unchanged after human abandonment) are
NH. In landscape ecology the management role of human populations—if not directed against nature—may
be considered as a semi-natural function.
Life processes and systemic attributes
As expressed by some scientists (Ingegnoli, 1980, 1993,
2001, 2002; Naveh and Lieberman, 1984,1994; Naveh,
1987; Leser, 1997; Meffe and Carrol, 1997), the landscape presents life processes and systemic attributes of
a self-organizing system at each biological level. Consequently a landscape (1) follows non-equilibrium thermodynamic, and (2) is subjected to the irreversibility of
time, the Principle of Emerging Properties, the ‘order
through fluctuation’ process (Prigogine and Nicolis,
1977; Naveh and Lieberman, 1984, 1994; Ingegnoli,
1991, 1993, 2002; Prigogine, 1996).
Focusing our attention on the main transformation
processes concerning the landscape, let us review the
main aspects:
Hierarchical structuring. The behavior of a landscape
and of all ecological systems is limited by (1) the potential behavior of its components (lower level of scale),
and (2) the constraints of the environment (upper level
of scale). These conditions represent the field of existence in which the system of ecocenotopes must reside.
Metastability. An ecological system can remain within a
limited set of conditions, but it may present alterations if
these conditions change. The system may cross a critical
threshold, approaching even radical changes (Ingegnoli,
2002). Therefore, different types of landscapes may be
correlated with diverse levels of metastability.
Israel Journal of Plant Sciences 53
2005
Non-equilibrium thermodynamic. Thermodynamic
bonds may determine an attractor that represents a
condition of minimum external energy dissipation in
its proper field of existence. Possible macro-fluctuations produce instabilities that move the system towards
a new organizational state. This new state allows an
increase of dissipation and moves the system towards
new thresholds to reach a new attractor. All this could
be represented as a cybernetic process of “order through
fluctuation”.
Evolutionary changes. The structuring of every biological system may be reached (i.e., the information may be
transmitted) only if the final state of the system considered
is less unstable (i.e., more metastable) than its initial state.
The modalities by which these processes are realized may
be different and not limited to a single scale.
Coevolution. The history of the interactions among the
elements of a landscape in a given locality shows a particular dominion that is characterized by the coherence
of the reciprocal adaptation of the elements themselves.
This process leads to a stabilization of the different
homeostatic capacities of a landscape, which may be
expressed with a particular degree of metastability.
Reproductive processes. Each level of life organization
presents typical reproductive components: (1) a system
that maintains information, (b) a mutation, (c) a protection of renewed elements, (d) a selection phase, and
(e) a crucial disturbance eliminating the old structure.
Therefore a landscape is able to reproduce itself.
Ecological Reproduction
At the organizational level of landscape, or of ecocoenotope, how does reproduction occur? There is no
doubt that it is different from the same processes at
organism level; nevertheless it has to occur. Information to be transmitted has to be circumscribed in time
and space, e.g., in a propagule-bank. An outbreak effect
must appear, for example, a “zero event” (Oldeman,
1990) or “crucial disturbance” (e.g., fire), allowing the
“propagula” to substitute previous organic structures.
For instance, through the renewal of the tesserae
forming an ecotope, a landscape may reproduce itself,
following the typical sequence of reproductive processes (Table 1). From the point of view of vegetation
science we have to underline the concept of ecological
memory (Bengtsson et al., 2003). It could be divided
into a within-patch memory and external memory to
show the different ecological processes. The within-site
processes can be viewed as assembly rules (e.g., propagule-bank, biological legacies, etc.), while among-site
processes may include such landscape functions as
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Table 1
Comparison of the main processes of reproduction of an animal population and of a landscape minimum unit
Population renewal
Reproduction process
Ecotope renewal
Predisposed gonads
Reservoir of information
Ecological memory
(e.g., propagule bank)
Chromosome crossing over
Mutation
Nest or parental cares
Young structure protection
Death, often deferred
Old structure death
Competition and predation
Selection
dispersal filters, pioneer belts, old tree sources, distance
from source, and range of disturbances. Crucial disturbances can be natural or human.
Re-colonization also plays an important role in selfreproduction. Pioneer phases tend to be stochastic, but
pioneer dynamics are oriented by strain conditions that
depend on the structure and dynamic of the landscape
unit. Time has a considerable functional importance:
therefore, the recreative phases of the elements of a specific landscape have to avoid too-rapid transformations.
Even human colonization is able to reproduce typical
ecotopes and landscapes almost all over the world. In
doing this, cultural tradition plays an important role,
even in an ecological sense.
NEW FUNCTIONS AND NEW METHODS
Crucial importance of vegetation in the evaluation
of a landscape
In reality, landscape ecology cannot represent the complexity of the landscape level only through an ecological mosaic. The new disciplinary model proposed by
Ingegnoli (2002) is based on the ecotissue (or ecological
tissue) concept, a complex multidimensional structure
built up by a main mosaic (generally formed by the
vegetation coenosis) and a hierarchic set of correlated
and integrated mosaics and information of different
temporal and spatial scales.
The role of vegetation coenosis is in accordance
with a non-equilibrium thermodynamic. Whereas an
energy concentration (i.e., photosynthetic plants) produces structure and organization in a landscape matrix
with increasing entropy, the “order through fluctuation”
process creates a patch that acquires a specific landscape
role. This may be the principal way through which
ecological systems become heterogeneous (Ingegnoli,
1980, 1999; Forman and Moore, 1991). Consequently, a
correct evaluation of the ecological state of a landscape
is impossible without the evaluation of its vegetation.
But this evaluation has to be in accordance with the
above-mentioned landscape ecological principles, as
follows:
Local disturbances
Nursery niches
Competition and predation
Crucial disturbance
1. First of all, the definition of vegetation must be: the
complex of the plants of a landscape element, considered in their aggregation capacities and in their
relations with environmental factors. Therefore, a
cultivated tessera has to be considered as vegetation
not only for its weeds (e.g., Secalinetea, Chenopodietea), but even for the cultivation itself (e.g.,
Triticum aestivum, Hordeum vulgare), without which
the weeds do not succeed and the tessera does not
become the habitat for many natural species (e.g.,
Coturnix coturnix, Alauda arvensis). Besides, this
type of vegetation is a crucial ecological component
for human populations.
2. Therefore, the following statement: “Vegetation is
organized in communities” (Pignatti et al., 2002)
(Fig. 2) is necessary but not sufficient. Vegetation
is organized in ecocoenotopes and in systems of
interacting ecocoenotopes (i.e., landscape), thus
involving both the hierarchic levels of the middle
biological spectrum. Consequently, in Fig. 1 we may
observe the emergence of other processes impossible
to consider at the community level, e.g., the ecotope
web, patch conditions, landscape disturbances, etc.
3. Finally, the processes of transformation of vegetation
need to be synthesized following the studies of Falinski (1998) modified by Ingegnoli (2002), as shown in
Table 2. The main processes are (1) Steady attractor,
(2) Transitory variations, (3) Instability processes, (4)
Destructive processes, (5) Recreative processes. Thus,
a complete understanding of the transformation modalities of the vegetation in a landscape need a proper
ecological function able to quantify these changes.
The biological territorial capacity of vegetation
The linkage between the ecological balance of a landscape and the ecological metastability has a very important dynamic significance. Trying to evaluate the metastability of a landscape, one has to refer to the concept
of biodiversity (in this case, landscape diversity) and to
the concept of latent capacity of homeostasis of an ecocoenotope. We start from this second concept.
Ingegnoli / Landscape ecology’s contribution to vegetation science
160
Table 2
Main transformation processes in vegetation
Transformation
Development phase
Main processes
Main results
1. Steady attractor
maturity
steady fluctuation
2. Transitory variations
maturity or near
maturity & adult
gradual and recurrent
exchanges of components
incorporation of disturbances
senescence or
alteration
out of scale disturbances
(non-incorporation)
3. Instability processes
4. Destructive processes
5. Recreative processes
growing & maturity
successional
new variations on transitory
variations
renewal and reproduction,
through inner and context
sources
Referring to the vegetation of an ecocoenotope, it is
possible to define a synthetic function, named biological territorial capacity or BTC (Ingegnoli, 1991, 1993,
1999, 2002; Ingegnoli and Giglio, 1999), on the basis
of (1) the concept of resistance stability (Odum, 1971);
(2) the principal types of ecosystems of the ecosphere
(Whittaker, 1975); and (3) their metabolic data (biomass, gross primary production, respiration, R/PG, R/B)
(Duvigneaud, 1977; Piussi, 1994; Pignatti, 1995). We
can elaborate two coefficients:
ai = (R/GP)i/ (R/GP)max
bi = (dS/S)min/(dS/S)i
where R is the respiration, GP is the gross production,
dS/S is equal to R/B and is the maintenance/structure
ratio (or a thermodynamic order function; Odum, 1971,
1983), and i are the principal ecosystems of the ecosphere. The factor ai measures the degree of the relative
metabolic capacity of the principal ecosystems; bi measures the degree of the relative antithermic (i.e., order)
maintenance of the principal ecosystems. We know that
the degree of homeostatic capacity of an ecocenotope
is proportional to its respiration (Odum, 1971, 1983).
So through the ai and bi coefficients, even related in the
simplest way, we can have a measure that is a function
of this capacity:
BTCi = (ai + bi ) Ri w
where w is a necessary variable to consider the Principle
of Emergent Property and to compensate the environmental difficulties.
It is possible to calculate an ecological index based
on the BTC function. The values of this BTC index,
associated with the statistical data on the landscape,
allow the recognition of regional thresholds of landscape replacement (i.e., metastability thresholds) and
of the transformation modalities controlling landscape
changes, even under human influence.
Israel Journal of Plant Sciences 53
2005
degeneration or regeneration
phases
unpredictable transformations
degradation or even death
seldom forecasted results,
because of the bifurcations
in non-equilibrium dynamics
An integrative approach to study vegetation
Landscape ecology criticizes other aspects linked with
the phytosociological method. For instance, the attempt
to replace the dogmatic climax concept with the more
meaningful “potential natural vegetation” is not satisfactory for landscape studies because the word “potential” is intended to represent undisturbed conditions in
an indefinite time. The proposal of Ellenberg (1974), to
distinguish among zonal, extrazonal, and azonal vegetation, is again not sufficient for landscape ecological theory and therefore even for vegetation science. Ellenberg
(1978) already perceived the ecosystem and the human
dual parts in the structure of a landscape, and Naveh
and Lieberman (1984) pointed out that Walter (1973)
proposed to determine plant formations and types not
only in their floristic aspect but also in their stability,
structure, human influence, diversity, productivity, etc.
The reasons for this criticism derive from the self-organization processes, when the role of disturbances is
seen as structuring and when the transgressions in a
linear succession are based on the interaction among
landscape elements even in the same zonal area.
Remember that the way to evaluate the vegetation
on the basis of its ecological distance from the potential
vegetation is not correct in landscape ecology because
we cannot imagine a potential landscape reduced to
very few (sometimes only one or two) types of vegetation. This is in contrast with all the main processes
and dynamics of the landscape! It is a sort of “virtual
ecology”! In fact, it clashes with the non-equilibrium
thermodynamic principle and the processes of self-organizing systems.
Therefore, the concept of potential vegetation has
to be changed. It has to be defined not only for natural
cases but also in relation to the main range of landscape
disturbances (including man) and with defined temporal
161
conditions. It must never be considered as the optimum
for a certain landscape (or part of it). It could be better
named fittest vegetation. This concept indicates the most
suitable or suited vegetation to (1) the specific climate
and geomorphic conditions of a certain limited period of
time in a certain defined place, (2) the main range of incorporable disturbances (including man’s), and (3) natural or unnatural conditions. This is a considerable change
of perspective. Note that it serves also to eliminate, or at
least to declassify, the concept of primary succession and
to change the concept of vegetation dynamics itself.
Consequently, phytosociology can be utilized only
if it is integrated with other methods, especially concerning landscape ecological characters. The vegetation units should be studied by gathering the following
information: (1) site data, geographic coordinates,
altitude, slope, climate, substrate, etc.; (2) descriptors
of biological components of the vegetation community,
i.e., height, stratification, biomass, biological forms
(sensu Box, 1987), green area index, interrelation with
the landscape, etc.; (3) consequences of human actions,
stress, forest exploitation, grazing, risks, endangered
species, history, etc.; and (4) landscape parameters,
i.e., metastability, boundary connections, disturbances
incorporation, tessera characters, etc.
The characters relating the vegetation to the landscape can be proposed in three forms: (1) a set of parameters (six to eight) measuring the relation between a vegetated patch and the landscape through an ecogram (i.e.,
radar plot), (2) a survey schedule for a vegetated tessera
(see below), and (3) the evaluation of the biological territorial capacity of a vegetated tessera (or ecotope) with
BTC indexes.
The evaluation of vegetation in landscape ecology
As emphasized before, the importance of vegetation
analysis and evaluation in landscape ecology is extremely high, but it needs a proper methodology. One of
the useful methods in which vegetation characters can
be related to landscape ecology is through a standard
form (or “survey schedule”, a proper one for each type
of vegetation) for the evaluation of a vegetated tessera.
The schedule (an example is shown in Table 5) has
been designed to estimate the metastability of a tessera,
considering both “general ecological” and “landscape
ecological” characters: T = landscape element characters (e.g., tessera); F = plant biomass above ground; E =
ecocoenotope parameters; U = relation among the elements and their landscape parameters.
The parameters for each T,F,E,U group range from
2 to 12, thereby reaching the number of about 26–32.
The evaluation classes are four: the weights per class
depend on an evaluation model representing the selforganization level and the metabolic potentiality related
to a system of ecosystems (Ingegnoli, 2002). This model
was built on the basis of the well-known relationships
among gross productivity, net productivity, and respiration in vegetation ecosystems (Odum, 1971; Duvigne-
Table 3
Evaluation equations of biological territorial capacity (BTC) ranked for the main vegetation types available in Europe
Vegetation types
Schlerophyll forest
Reference max. value
of BTC
Maturity thresholds
(years)
BTC evaluation equations
(Mcal/m2/year)
13.0
120–150
0.01705 (y-28) + 0.13 (pB/60)
Temperate forest
12.0
Medit. pine forest
10.5
100–130
7.5
70–110
Boreal alpine forest
Corridors with trees
Urban gardens
Wooden agrarian
Tall shrubs
Low shrubs
Reed thicket
Wet prairie, bogs
11.0
8.5
4.5
4.0
2.6
2.5
2.0
120–150
120–150
90–130
25–45
30–40
25–35
36–48
25–30
Agricultural fields
1.9
10–20
Salt marshes, prairie
1.2
15–20
Prairie and pasture
1.4
20–24
0.01667 (y-28) + 0.13 (pB/65)
0.01339 (y-28) + 0.12 (pB/70)
0.01510 (y-28) + 0.12 (pB/65)
0.0072 (y-33) + 0.10 (pB/75)
0.00526 (y-30) + 0.10 (pB/45)
0.00575 (y-29) + 0.15 (pB/35)
0.00344 (y-30) + 0.10 (pB/17)
0.00247 (y-30) + 0.03 (pB/0.2)
0.0023 (y-29) + 0.04 (pB/0.3)
0.0016 (y-29) + 0.02 (pB/0.14)
0.00192 (y-26) + 0.09 pB
0.001335 (y-29) + 0.02 (pB/0.14)
0.0026 (y-28) + 0.10 (pB/1.4)
Data from: Ingegnoli, 2002; Ingegnoli and Giglio, 2005. y = total score of the survey schedule, pB = measured value of plant
biomass in each examined tessera.
Ingegnoli / Landscape ecology’s contribution to vegetation science
162
aud, 1977). Therefore the development of a vegetation
community shows (1) an exponential growing phase
from young adult to maturity, and (2) a logarithmic
growing phase from maturity toward old age. Each
curve presents in the transition phase (1–2) its own BTC
values, defined after a control through the field study of
critical points referred, for instance, to plant biomass
relations, and structural and ecological parameters.
These schedules are very useful to verify a level of quality (Q) and to estimate the biological territorial capacity
(BTC) of the vegetation through a proper equation (Table
3). At present, 10 standard forms have been elaborated and
tested, concerning 14 types of vegetation both natural and
human (Table 3). Schedules and results can be utilized both
in evaluation studies (allowing the possibility to detect
evidence of recurrent negative characters) and in therapeutic ones (permitting one to choose parameters needing an
intervention and to measure and control the results).
EXAMPLES AND RESULTS
Evaluation and diagnosis
A clinical-diagnostic method is indispensable to study
a complex living system like a landscape. To acomplish
this we have to compare the ecological data with a series
of “normal behaviors”. An ecological diagnosis depends
on the comparison between the conditions of the system
examined and the conditions of the state considered a
normal one for this type of ecosystem. Therefore, this
assessment needs the integration of local and species
parameters. The new functions and the new methods
presented in this paper enhance the diagnostic evaluation of the ecological state of the systems examined, as
we will present in two abstracts of case studies.
Evaluation of the vegetation of the Venice lagoon
This preliminary research deals with a very complex situation: the ecological state of the landscape of the Venice lagoon. The study was commissioned by the Venice
Water Authority (Magistrato alle Acque di Venezia) and
the CVN (Consorzio Venezia Nuova) (Ingegnoli, 2003).
I will summarize here only some of the research related
to the evaluation of the vegetation of the landscape.
Figure 2 shows the seven groups of vegetation types of
the lagoon landscape. In the last century this vegetation
has been considerably reduced in its surface (Fig. 2),
especially in the natural components (salt marshes or
“barene”), and simplified in the anthropogenic components (total decrease of woody agrarian).
In this framework, it is of crucial importance to
evaluate the landscape vegetation (both natural and
anthropogenic). A summary of the present qualities (Q)
and biological territorial capacity (BTC) of the main
vegetation types of the lagoon is presented in Fig. 2:
the natural and semi-natural vegetation reaches 27.9%
of the vegetated areas (in total 37.6%), therefore only
10.5% of the landscape area, with a medium quality
(50.5%) and a low BTC (0.59 Mcal/m2/year). This is
Fig. 2. The surface covered by the main groups of vegetation of the Venice lagoon landscape and its dynamic in the last century.
Note the decrease of the total vegetated areas, especially of the salt marshes or “barene”. This important natural vegetation is
composed of three main alliances: Puccinellio-salicornion, Thero-salicornion, and Juncion maritimi (Pignatti, 1966).
Israel Journal of Plant Sciences 53
2005
163
Fig. 3. Synthesis of the evaluation of the main landscape vegetation groups of parameters derived from the “barene” (salt
marshes) schedule after nearly 60 surveys (Ingegnoli and Giglio Ingegnoli, 2004).
Table 4
Synthesis of some of the most significant landscape ecological parameters referred to the
preliminary study of the Venice lagoon landscape (Ingegnoli, 2003)
Main landscape ecological
parameters
1900
Year
1950
2000
Re-balance
targets
Habitat ratio, HH/NH (%)
36.9
59.8
61.7
60 ÷ 61
28.5
19.0
11.0
BTC (Mcal/m /year)
2
Salt marshes/tidal area
Deviation from HH/BTC model (%)
Resistant apparatus (woods) RNT (%)
Ecotonal vegetation belts ETN (%)
Landscape diversity ratio ψ/τ
0.51
–23.5
1.99
7.32
2.24
0.35
–26.1
1.40
3.95
2.51
0.29
–27.5
1.76
4.24
3.14
0.38 ÷ 0.40
18 ÷ 20
± 15
4÷5
7÷8
2.2 ÷ 2.4
ψ landscape ecological index of structural diversity, considering landscape element types (Ingegnoli and Giglio,
2005); τ landscape ecological index of functional diversity, considering both heterogeneity and information
among classes of vegetated tesserae (Ingegnoli, 2002).
due to the dominance of underwater grasslands (Zostera and Cymodocea sp.) and of Limonieta salt marshes
(Limonietum venetum Pignatti 1966), while the lagoon
margins present few remnant wood patches and tree
corridors.
In Fig. 3, we can see in detail the synthesis of the
main parameters of landscape vegetation related to salt
marshes (“barene”). Even in the most positive scenario,
only the ecocenotope parameters reach a good evaluation level (80%), while the tessera parameters remain
about 45% of the best possibility.
The evaluation of the landscape vegetation represents the most important way towards the comprehension of the criteria of restoration of the Venice lagoon
landscape, as shown in Table 4, where the dynamics of
the main landscape parameters during the last century
are compared with re-balance ecological targets. These
comparisons depend on the building of ecological models in which the diagnostic evaluation of vegetation is
essential (Ingegnoli, 2002). Not one of the present values of the examined landscape is acceptable.
Ingegnoli / Landscape ecology’s contribution to vegetation science
164
Evaluation of the forested landscape of the Lavazè
Pass
The small landscape unit (LU) of the Passo Lavazè (173
ha) in the Western Dolomites (1800 m a.s.l.) is formed
by 4 ecotopes, 3 of which are forested (HomogynoPiceetum Zukrigl 1973). This LU presents a quite high
level of BTC (4.76 Mcal/m2/year) with an HH/NH ratio
equal to 0.36 according to the ecological values of a
semi-natural landscape.
An example of the survey schedule proposed by
the above-mentioned method of Ingegnoli (Ingegnoli,
2002) is presented in Table 5, referring to one of the
evaluated forested tesserae. The result is a total score
(Y) equal to 513, the quality (Q) equal to 73.3%, and
Table 5
Forest permanent plot TRE1 (Lavazè Pass, Alps) Piceion abietis, 1,800 m a.s.l.
Boreal Forest
1
5
14
25
score
<9
<30
low
none
simple coppice
< 80
9.1–18
>90
medium
<30
coppice
81–160
18.1–29
31–60
good
31–89
wood
161–240
>29.1
61–90
high
>90
natural forest
>240
Canopy
Ts surface
Age, space groups, etc.
(% Ts)
Or similar
Old trees
near 0
near 0
<200
>10
<1.5
201–500
1–5
1.6–3.5
501–950
5–10
>3.5
>950
% of living biomass
cm
pB = 696 m3/ha
>3
<15
<5
>10
near all
evident
<3
2
none
degradation
3
16–30
6–40
10–4
>25
suspect
4–5
3
intense
recreation
2
31–40
41–80
<4
<25
risk
6–7
4
sporadic
regeneration
1
>40
>80
0
0
0
>7
>4
normal
fluctuation
As pB volume
n° sp./Tessera
Phytosociological
From other ecoregions
Coverage on Ts
Even acid rain damage
Cfr. Box, 1987, mod.
Traditional
Dominant species
Cfr. Ingegnoli, 2002
<25
neutral
minor
scarce
partial
medium
gradual
changes
near
chronicle
100–300
26–75
partial
evident
normal
risk
good
temporal
instabilities
easy to
incorporate
300–1200
>76
source
important
high
none
attraction
fluctuation
none
% of perimeter
Species and resources
Context and typology
Local disturbances
On the phisiotope
Key species
Today
+ tendency
From landscape
>1200
Historical presence
w = 11
Y = 513
Q = 73.3 [%]
BTC = 7.69
[Mcal/m2/a]
T. Tessera characters (Ts)
T1.
T2.
T3.
T4.
T5.
T6.
Vegetation height (m)
Cover of the canopy (%)
Structural differentiation
Interior/edge (%)
Management
Permanence (years)
F. Vegetational biomass (above ground)
F1. Dead plant biomass
F2. Litter depth
F3. Biomass volume (m3/ha)
E. Ecocenotope parameters
E1. Dominant species (n°)
E2. Species richness
E3. Key species presence (%)
E4. Alloctonous species (%)
E5. Infesting plants (%)
E6. Threatened plants
E7. Biological forms (n°)
E8. Vertical stratification
E9. Renewal capacity
E10. Dynamic state
U. Landscape unit (LU) parameters
U1. Similar veg. contiguity
U2. Source or sink
U3. Functional role in LU
U4. Disturbances incorporation
U5. Geophysical instabilities
U6. Permeant fauna interest
U7. Tranformation modalities
of the Ts
U8. Landscape pathology
interference
U9. Permanance of analogous
vegetation (years)
0
sink
reduced
insufficient
evident
low
strong
distubances
serious
<100
Results of the survey
Total score Y (= h+j+k+w)
Quality of the Ts
Estimation of the BTC
J=0
K = 17
Q = Y / 700
BTC (b) = 0,01339 (y–28) + 0,12 (pB / 70)
h=0
Israel Journal of Plant Sciences 53
2005
165
Fig. 4. Values of the main ecological sets of parameter measured with the mentioned survey schedule in percentage of their
normal optimum state. Case study: the landscape unit of Lavazè Pass (Trentino–AltoAdige), after the survey of 11 forested
tesserae.
the BTC equal to 7.69 Mcal/m2/year. Moreover, the first
set of characters (T) reaches 70.67% in quality, while
the qualities of (F), (E), and (U) are 56%, 82.4%, and
70.67%, respectively.
In this case study, the main values resulted after the
evaluation of all the forested tesserae are reported in
Fig. 4. The results are better than the case presented in
the salt marshes of the Venice lagoon. The difference
between the best and the worst surveyed tesserae is
remarkable. Note that the ecocenotope parameters are
quite good in every tessera. This is a relevant observation, because these are the traditionally measured
parameters while the other sets (presenting a different
ecological state) usually are not assessed. This diagnostic evaluation of the landscape vegetation allows one
to propose therapeutic interventions in this landscape
unit, based on the comparison with ecological models.
It is now possible to answer questions like: Does the LU
present an alteration syndrome? or What is the minimum
number, extension, and position of forested tesserae to
be preserved in a completely natural condition?
CONCLUSIONS
This paper tries to demonstrate that the advancement in
landscape ecological theory leads to improving many
aspects of vegetation science: (1) a more coherent
study of both natural and anthropogenic vegetation;
(2) a better evaluation of landscape metastability; (3) a
better understanding of transformation processes; (4) a
confirmation of the necessity to abandon deterministic
concepts (e.g., potential vegetation, primary succession); and, especially, (5) a new capacity for landscape
vegetation evaluation and diagnosis. The last one could
be expanded further, into: (5.1), better possibilities of
therapeutic intervention in nature conservation, and
(5.2) more coherent building of ecological models that
can link vegetation with other landscape parameters.
ACKNOWLEDGMENTS
Many sincere thanks to Elena Giglio Ingegnoli, Marco
Ferraguti, and Linda Whittaker for the reviewing of the
article and to Sandro Pignatti for the discussion on the
limits of phytosociology.
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