ÉOCARREFOUR
Retief GROBLER
University of Pretoria
South Africa
Christoph Moning
Jan SLIVA
Technische Universitate
Munchen, Germany
George
BREDENKAMP
University of Pretoria, South
Africa
Piet-Louis
GRUNDLING
Working for Wetlands
Programme, South Africa
ABSTRACT
Maputaland is a region of
exceptionally rich
biodiversity located in the
north-eastern corner of
Kwazulu-Natal and forms
the southern most tip of the
Mozambique coastal plain. It
can be considered as the
most southern end of the
tropics in Africa and
consequently many tropical
species reach their southern
most distribution boundary
here. Maputaland is the
largest peat containing
region in South Africa with
60 % of the country’s peat
present therein. Coastal peat
swamps forests are more
abundant in Maputaland
than anywhere else in South
Africa, but remain poorly
studied as far as their
vegetation composition,
structure, functioning, and
the nature and impact of
exploitation on them are
concerned.
In this ongoing study an
initial vegetation and
environmental dataset of
May 2003 was used to
assess the impact of
subsistence farming,
predominately with
madumbes (Colocasia
esculenta) and bananas
(Musa xparadisiaca), on
coastal peat swamp forests.
A TWINSPAN numerical
classification resulted in the
identification of 10
vegetation groups,
exhibiting a gradient from
pristine to highly disturbed
peat swamp forests. The
pristine peat swamp forest
group is separated on the
degree of wetness, ranging
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317
Subsistence farming and conservation
constrains in coastal peat swamp forests
of the Kosi Bay Lake system, Maputaland,
South Africa
Coastal peat swamp forests (CPSF) can be
classified as fresh water forested wetlands (photo
1) that are established on peat soils (photo 3) in
open ended riverine interdune valleys in close
proximity to a marine water body. Coastal peat
swamps forests are highly threatened ecosystems
in South Africa, being the second rarest forest type
in the whole country and only occur in isolated
patches from the Mozambique border to just
south of the Msikaba River in the Eastern Cape
(Moll, 1980 ; Wessels, 1997). Roughly 3 986 ha of
swamp forest occur in Maputaland (fig. 1) of which
a great deal is still unclassified due to their
remoteness and inaccessibility, the swamp forests
on the flat coastal plain of Maputaland form 75 %
of all swamp forest found in South Africa which
make them very valuable for future conservation
(Lubbe, 1997).
The largest intact individual peat swamp forest in
South Africa occurs adjacent to the Syhadla river,
the main source of fresh water for the Kosi Bay
Lake System (KLS), with a total area of 880 ha
(Wessels, op. cit.) (fig. 1). The Kosi Bay Lake
System in the north-eastern corner of Maputaland
is a unique chain of 4 linked coastal lakes forming
both an estuary and freshwater wetland (Begg,
1980). Due to its uniqueness and subsequent
international importance it was classified as a
Ramsar site in 1991(Cowan and Van Riet, 1998).
CPSF in South Africa and especially those around
Kosi Bay are unfortunately under threat from
various sources. In the past large areas of swamp
forest were cleared for sugarcane farming,
forestry, slash and burn agriculture, and
eradicating of teste fly and mosquito habitat, but
are now provided better protection through
legislation and alternative insect pest control
practices. Legislation has however been found
insufficient in regulating aspects having bearing
on communal rural areas, especially relating to
wetland cultivation (Kotze, 2002).
The Tonga people of the Tembe Tribe have been
living next to the KLS for centuries and relied
heavily on coastal peat swamp forests as a source
of fresh drinking water and as the only available
productive land for cultivating crops. As the
peatlands retain surface water and water released
from perched aquifers in the dunes very well and
the surface Quaternary dune sediments are
nutrient-poor (Grundling, 1996). The inclined
swamp forest valleys’ slopes facilitate easy
drainage of the peat and resulted in traditional
cultivation techniques of cutting drainage ditches
and constructing raised beds. This gradient of
hydrological modifications enable the gardening
of a wide variety of crops, with bananas (Musa
x p a r a d i s i a c a) and madumbes (C o l o c a s i a
esculenta) being the most common (Grundling,
op. cit. ; Kotze et al. 2004).
Tension between the local Tonga inhabitants and
the controlling conservation authority, Ezimvelo
Wildlife has been high for many years as they
were forcibly removed from their land in 1988 with
the proclamation of the Kosi Bay Coastal Forest
Reserve. A changing socio-economic environment
has placed a greater demand on bananas and
other peat swamp forest derived crops, mainly
because of the following (Herrington and
Compton, 2003) :
- a general increase in population growth as health
services and infrastructure have improved over the
last few decades ;
- many miners have been retrenched as mines
closed in Gauteng and the Free State, forcing
migrant workers to return home and turn to peat
swamp forest gardening as their primary means of
survival ;
- portuguese and Tonga speaking illegal
immigrants continue to flock to the area, while the
Tembe people do not treat them, especially fellow
Tongas, with antagonism, but rather feel obligated
to help them, leading to yet more gardens being
established ;
- HIV/Aids is also becoming a serious problem
causing yet more poverty as the breadwinners are
commonly those most at risk to the disease. As the
disease proliferates it creates the need for yet
more nutrient supplements to remain productive
for as long as possible. The fish kraals at Kosi
Mouth and peat swamp forest habitat are the two
main reliable natural resources guaranteeing food
security.
METHODS AND MATERIALS
A total of 34 sites surrounding the KLS were
visited during May 2003. Individual peat swamp
forests sites were affected by a wide array of
different land uses as they occurred within and
without the boundaries of the Kosi Bay Coastal
Forest Reserve. Different peat swamp forest sites
were classified into one of four mutually exclusive
disturbance categories :
- pristine peat swamp forest
- recently disturbed peat swamp forest
- old disturbed recovering peat swamp forest
- active gardening in peat swamp forest.
Most often the specific category was apparent in
the field, but in some cases, especially the old
disturbed recovering peat swamp forests,
information was gathered from local people that
have been farming in the area for sometime. It was
however essential that each recorded site had to
be a peat swamp forest sometime in the past
irrespective of how it looked at the time of
investigation. An additional requirement for each
sampled site was that it still had to contain a
distinguishable peat layer, irrespective of its depth,
to ensure that is was still a peat swamp forest or at
least had the potential to become one again in the
future. Selected peat swamp forest sites were
randomly sampled by means of 10x10 m plots,
restricted to areas with a relatively homogenous
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VOL 79 4/2004
Subsistence farming and conservation constrains in coastal peat swamp forests
Figure 1 : Location of
Maputaland and Studied area
in South Africa
vegetation pattern to ensure an authentic
representation of all sampled vegetation types.
Inside each plot all the presented plant species
were recorded and assigned an appropriate BraunBlanquet cover-abundance value (Werger, 1974).
The vegetation in each plot was separately
assessed in four different layers : tree (T), shrub
(S), herb (H), and liana (L) layer. The height of each
layers, when present, was decided on based upon
the physiognomy of each plot. If the same species
occurred in more than one layer, it was recorded
as a separate entity in each one. Data on the
habitat were also noted and included a subjective
categorical classification of the hydrology of the
peat soil surface, as either flooded, wet, moist, or
dry. The presence of drainage ditches associated
with gardening activities was also noted, as well as
peat depth as determined with a standard clay
auger up to 1.5 m deep. Additional general notes
on the nature of any visual disturbances were also
recorded and included remarks on cutting and
clearing, fire, and active gardening.
The importance of local knowledge was highly
esteemed during the entire duration of the field
work phase and included several informal
discussions with farmers on the period of active
farming or absence, their main fears and
grievances, as well as their attitude towards peat
swamp forests and its continued existence.
The collected floristic data were captured into the
TURBOVEG data basis (Hennekens, 1996) and
thereafter analyzed by means of classification and
ordination techniques to identify diagnostic
vegetation types. The Two Way Indicator Species
Analysis (TWINSPAN) numerical classification
procedure (Hill, 1979) was initially used for a
classification of the vegetation. This procedure not
only distinguishes distinct identified groups, but
also the relationships between the groups. The
relationship between the different vegetation
types are represented in a dendogram. An
ordination to identify and quantify the importance
of the main environmental factors responsible for
the distributing pattern of the plant species in the
area was achieved v i a a Detrended
Correspondence Analysis (DECORANA/DCA) (Hill
and Gauch, 1980). This ordination procedure was
performed by means of PC-ORD4 software and
represented in a graph. The ordination differs
from the traditional phytosociological usage in
that the identified groups are not grouped
according to their associated vegetation type, but
according to their disturbance category, as
indicated above.
RESULTS
Coastal peat swamp forest vegetation groups are
distinguished primarily on the level of human
interference, according to the numerical
classification (fig. 2). The pristine peat swamp
forest group displays a gradient between wet and
dry swamp forests. Raphia australis and Syzygium
cordatum - Schefflera umbellifera Peat Swamp
Forest grow in drier conditions without any
manmade modifications to the peat hydrology,
while Syzygium cordatum - Voacanga thouarsii
Peat Swamp Forest and Syzygium cordatum Ficus trichopoda Riverine Peat Swamp Forest
dominate on progressively wetter valley peatland
soils. The dry pristine swamp forest group
consists of large endemic stands of R a p h i a
australis palms, distinctive on the western shore
of Lake Amanzimnyama, as well as recovered
peat swamp forests that have been disturbed long
from wet to dry peat swamp
forests, while the highly
disturbed group is divided
according to the presence or
absence of active gardening.
A Detrended
Correspondence Analysis
(DCA ordination)
determined anthropogenic
practices involving tree
felling and peat draining as
the main factors responsible
for peat swamp forest
habitat modification. The
change in swamp forest
structure and peat
hydrology critically
threatens the continued
existence and ecological
functioning of these
systems. This impacts
negatively on habitat and
biodiversity loss and will
eventually deprive the rural
community of a sustainable
gardening environment,
bring about a change in the
lake system’s nutrient
balance, and even reduce
available sources of clean
and fresh water.
The situation poses an
urgent conservation
challenge for the
conservation agency and
local community whose
livelihood is intricately
interwoven and pivoted
around their peat swamp
Subsistence farming and conservation constrains in coastal peat swamp forests VOL 79 4/2004
forest environments. Before
progress can however be
made trust needs to be
established between the
different stakeholders,
looking beyond solutions of
complete exclusion, but
rather to mutual
cooperation, involving
practices such as wise use
gardening management.
KEYWORDS
Peatlands, swamp forests,
gardening, Kosi Bay,
Maputaland, South Africa.
RÉSUMÉ
Le Maputaland est un
secteur de la province du
Kwazulu-Natal, une région
située au nord-est de
l’Afrique du Sud, près des
frontières avec le Swaziland
et le Mozambique. Ce
secteur correspond d’un
point de vue géomorphologique à l’extrémité sud de
la plaine côtière du
Mozambique et d’un point
de vue bio-climatique aux
confins méridionaux de la
zone tropicale africaine.
Aussi de nombreuses
espèces tropicales se
trouvent ici à la limite de leur
aire de répartition.
Le Maputaland accueille par
ailleurs l’essentiel des zones
tourbeuses d’Afrique du Sud
avec 60 % des tourbières
nationales. Celles des forêts
marécageuses - swamp
forests - de la région côtière,
bien que les plus riches d’un
point de vue biologique,
sont parmi les moins bien
étudiées alors même
qu’elles sont sérieusement
menacées de disparition par
la très forte pression des
communautés agricoles
locales.
Les études dont cet article
rend compte s’appuient sur
une base de données
constituée en mai 2003 à
partir de 34 sites tourbeux
sites au cœur des forêts
marécageuses. Elle
comporte un ensemble
d’informations relatives à la
végétation mais également
ago and re-established on shallow peat (Syzygium
cordatum - Schefflera umbellifera Peat Swamp
Forest). Syzygium cordatum exhibits a grade of
peat hydrological preferences, but remains absent
in the very dry Raphia australis and very wet Ficus
trichopoda dominated vegetation groups.
The heavily disturbed peat swamp forest
vegetation group is characterized by a general lack
of a fully developed tree layer as well as
hydrological modifications made to the peat by
means of drain ditches (fig. 2 and fig. 3). Active
gardening related peat swamp forest destruction
(photo 3A and B) mainly consists of bananas
(Musa xparadisiaca) cultivated on the drier upper
swamp forest peatland soils (Musa xparadisiaca
Garden) (photo 3C) and madumbes (Colocasia
esculenta) (photo 3D) grown in both wet and dry
conditions normally towards and around the
centre of the valley peatland (Colocasia esculenta
Garden). Bananas are more dependant on
sunlight, which requires a more open canopy and
leads to greater clearing and cutting of swamp
forest trees (photo 4). Drier wetland conditions
preferable for banana growth is created by
drainage ditches running perpendicular to the
valley’s length, cutting through the peat and
causing intensified peat decomposition. Site
investigation and dialogue identified bananas as
the most favoured crop species by swamp forest
farmers where growing conditions are favourable
or can be modified to be so. Banana gardening
causes therefore more peat swamp forest
destruction than any other crop type. Madumbes
also known as taro or cocoyams cause the least
impact on peat swamp forest exacerbation as it
grows well in wet or dry and shaded or unshaded
conditions (De La Pena, 1983). The minimal human
interference required for its cultivation, in terms of
alterations to the existing peat and vegetation
cover, merits its use as the most preferred crop
species from a conservational perspective. As
gardening drives peat decomposition and the peat
becomes mixed with the underlying sand the
fertility and water holding capacity is progressively
lost from the edge of the valley peatland inwards.
The result for the farmers is a succession of crops
from bananas, madumbes and sugarcane
(Saccharum officinarum) to smaller and less
nutrient rich vegetables such as, sweet potatoes
(Ipomoea batatas), tomatoes (L y c o p e r s i c o n
e s c u l e n t u m), and pumpkin (Cucurbita pepo)
before gardens are finally abandoned.
Disturbed peat swamp forest vegetation units in
which no cultivation is currently taking place could
be caused by a small number of factors : fire and
natural die off are prone to Raphia australis Cladium mariscus Disturbed Peat Swamp Forests
where the drier conditions place the palm
dominated forest with abundant dry biomass at
risk to fire. Natural gaps are created in the
vegetation strata as cohorts of monocarpic Raphia
319
australis palms die and fall over after flowering.
Raphia australis is endemic to the area and
therefore well protected (Van Wyk, 1994) with
anthropological impacts limited to the collection of
fallen rachi for construction material (Lubbe, op.
c i t .). Traditionally this light and durable wood has
been a very important component in Tonga
livelihood, but one that is increasingly viewed as a
sign of poverty and therefore only utilized by those
that have no other means available (Ngubane,
pers. comm.). Wetter areas where cultivation has
ceased in the not too distant past remain as open
swamps, typically at valley bottoms where
conditions have become too wet and draining
insufficient to sustain farming. These open
swamps are characterized by vegetation groups
such as Typha capensis - Cyperus prolifer Open
Wetland and Cyperus textilis - Ipomoea batatas
Relic Garden. The latter still contains some sweet
potatoes individuals, as well as shaped mounds
traditionally used to cultivate smaller vegetables
species in wet conditions and remain as "fossil
gardens" (Grundling, op. cit. and pers. comm).
1. Pristine Raphia australis Peat Swamp Forest
2. Syzygium cordatum - Bridelia micranta Peat
Swamp Forest
2.1 Syzygium cordatum - Schefflera umbellifera
Peat Swamp Forest
2.2 Syzygium cordatum - Voacanga thouarsii Peat
Swamp Forest
2.3 Syzygium cordatum - Ficus trichopoda Riverine
Peat Swamp Forest
3. Colocasia esculenta Garden
3.1 Colocasia esculenta - Lycopersicon esculentum
Garden
3.2 Colocasia esculenta - Erythrina lysistemon
Garden
4. Musa xparadisiaca Garden
5. Raphia australis - Cladium mariscus Disturbed
Peat Swamp Forests
6. Typha capensis - Cyperus prolifer Open Wetland
7. Cyperus textilis - Ipomoea batatas Relic Garden
The importance of anthropological factors in
determining the distribution of different disturbance classes within peat swamp forests is evident
from the DCA ordination. Measurable attributes
best correlated with Axis 1 (eigenvalue = 0,729,
length of gradient = 4,488) include the percentage
tree canopy cover (tree co, r-value = -0,81),
presence of drain ditches (abbreviation : drain di ;
r-value = 0,691) and pristine relevés (abbreviation :
pristine ; r-value = -0,472) (fig. 3). These features
highlight the distinct difference in the structural
intactness of the various disturbance categories, as
displayed by the non-continuous relevé
distribution paralleled to Axis 1. An intact tree
canopy is prevalent among the Pristine and Old
disturbed recovering groups, while Gardening and
Recently disturbed groups generally lack an
integral canopy, except where gardening occurs
underneath tall trees, as at the Colocasia esculenta
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Subsistence farming and conservation constrains in coastal peat swamp forests
- Lycopersicon esculentum and C o l o c a s i a
esculenta - Erythrina lysistemon gardens of relevés
SYD-1 and MAL-1 respectively. Or the recent
disturbance has been limited to the clearing and
burning of the herb and shrub layer in preparation
or extension of gardening practices, as at the
Syzygium cordatum - Bridelia micranta Peat
Swamp Forest and Colocasia esculenta Lycopersicon esculentum Garden vegetation
groups of relevés SY-2, NK-1 and SF1-2
respectively. Pristine and Old disturbed recovering
groups exhibit little difference in their tree canopy
variation as a measure of structural intactness.
The highest correlated attribute with A x i s 2
(eigenvalue = 0,564 ; length of gradient = 4,981) in
the vertical direction is the hydrology or wetness
of peat soils (abbreviation: hydr ; r-value = 0,611)
(fig. 3). Pristine and Old disturbed recovering
groups are of an intermediate wetness as the drier
Raphia australis Peat Swamp Forest relevés of RA1 and RA-2 are the only real exceptions. The definite disjunction between Gardening and Recently
disturbed identified groups along Axis 2 is a clear
indication in the different hydrological regimes
between the two. The Recently disturbed group is
commonly cleared of vegetation, including the tree
layer, but has not yet been drained as gardening
still has to commence and remains therefore
wetter as opposed to the Gardening group.
Intermediate Gardening group relevés such as
SYD-1 and MAL-1 belong to the C o l o c a s i a
esculenta Garden vegetation group, which grow
well in a wide variety of hydrological conditions
(see text above), while some farmers continue to
grow bananas in spite of wet conditions as at
relevé NK-3 (Musa xparadisiaca Garden).
Conclusion
Prior to the interference of man on the intensity
level of the last few decades, peat swamp forests
in the Kosi Bay Lake System remained in a near to
pristine-like condition with a characteristic forests
vegetation and woody peat composition
(Grundling et al., 1998 ; Grundling et al., 2000).
Without the external influences of humans,
especially effective in altering the vegetation’s
structure and peat moisture contend, the
ecosystem’s functioning is principally depended
upon their wet hydrological regime. As hydrology
was the main factor that best explained the
relationship between the individual relevés of the
least modified Pristine and Old disturbed
recovering groups (fig. 3).
Traditional Tonga practices enabled the
community to live in harmony with their wetlands
for several generations, as they rotated their
gardens on a chosen peatland (Grundling, op. cit.)
and still have wetland habitat that remain intact in
spite of their presence over several centuries.
Population densities have, however, increased
since, bringing these systems under increased
pressure, which impede fallowing and lead to
progressive peat decomposition as abandoned
agriculture land becomes occupied by others. This
stresses the need to introduce and implement best
management practices pertaining to peat swamp
forest gardening, such as minimizing drainage,
building awareness and utilizing compost as a
growth medium supplement to peat (Kotze et al.,
op. cit.).
Tourism in this largely pristine area is playing an
increasingly important role in the local economy
as access and tourist numbers improve due to
better infrastructure, such as new roads and
lodges, and wider circulated publicity. It is clear
that the local inhabitants know how to manage the
wetlands for their own benefit, reconciliation
between their traditional practices and Westernstyle conservation could really boost ecotourism
and the local economy (Grundling, op. cit.). Up to
now tourism has been unsuccessful to bring
about the desired social and environmental
benefits to the Kosi Bay area, and while tourism
has the capability to make a definite contribution
to the situation it needs to be administrated with
care (Kotze et al., op. cit.). The different perspectives of conservation and utilisation become
incompatible in the sense that the age old inherent
practice of sustainable wetland utilisation is
threatened : the demand on environmentally
derived commodities have drastically increase in
order to attain financial freedom in an escalating
capitalistic driven society, which have caught up
with the people from Kosi Bay. The direct result is
the shift of peat swamp forest gardening from
simply a subsistence activity to a commercial
farming pursuit. The latter practice not being
justifiable on such a threatened and important
functioning ecosystem. Having said this, swamp
forest peat soils still provide the only truly viable
habitat for cultivation, due to its water retainability,
reasonable fertility and ease of draining. It
therefore continues to be the agricultural refuge
for many remaining subsistence level farmers in
the otherwise marginal landscape.
How to find the best balance between the different
peat swamp forest stances remain an unsolved
challenge, which needs to address the prime
agents responsible for peat swamp forest’s
decline in the Kosi Bay Lake System. Answers
point beyond the mere exclusion of slash and
burn farmers, but calls for the building of trust and
mutual understanding between the concerned
stakeholders. With this foundation in place the
intricate and multifaceted pull of poverty, a key
superseding driving force in habitat destruction
and unsustainable livelihood, could be contested.
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Adresse des auteurs :
Retief GROBLER
University of Pretoria
Department of Botany
Hatfield 0002
South Africa
E.mail : [email protected]
Christoph MONING
Technische Universitate
Munchen
Chair of Vegetation Ecology
85350 Freising
Germany
Jan SLIVA
Technische Universitate
Munchen
Chair of Vegetation Ecology
85350 Freising
Germany
George BREDENKAMP
University of Pretoria
Department of Botany
Hatfield 0002
South Africa
Piet-Louis GRUNDLING
Working for Wetlands
Programme
P.O. Box 912924
Silverton 0127
South Africa
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VOL 79 4/2004
Subsistence farming and conservation constrains in coastal peat swamp forests
Figure 2 : A dendrogram showing the hierarchy of TWINSPAN divisions for the vegetation data of peat swamp forest of the Kosi Bay Lake
System.
Figure 3 : A scatter diagram of
DECORANA ordination illustrating
the correlation of identified
disturbance categories with the
main environmental factors.
Subsistence farming and conservation constrains in coastal peat swamp forests
Photo 1 : A general view of Kosi
Bay coastal peat swamp forest in
Maputaland (South Africa)
Photo 2 : Peat soil of the coastal peat swamp
forest (Maputaland, South Africa)
Photo 4 : The landscape of the Kosi Bay
coastal forest after several years of gardening
by the Tonga people of the Tembe tribe
Les photographies sont de Hervé Cubizolle et Céline Sacca
VOL 79 4/2004
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VOL 79 4/2004
Subsistence farming and conservation constrains in coastal peat swamp forests
Photo 3A
Photo 3 : A, B, C and D : Gardening inside
the Kosi Bay coastal peat swamp forest
(Maputaland, South Africa). Bananas (Muxa
xparadisiaca) and Madumbes (Colocasia
esculenta) were planted after the clearing of
the peat swamp forest
Photo 3B
Photo 3C
Photo 3D