Landscapes Forest and Global Change - ESA - Escola Superior ...

T. Höbinger et al. 2010. Impact of changing cultivation systems on the landscape structure of La Gamba
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compact shaped landscape patches (O’Neill et al. 1988). With exception of section Bonito 2 all
rural sections had higher fractal dimensions than forests. Due to the inclusion of linear
landscape elements these high values indicate rather a high density of linear elements than a
high complexity of the matrix. The comparison of AREA and PD clearly showed differences in
the configuration of the patch types. Primary forests had the biggest extend, but comprised only
few patches. Secondary forests were characterized by a much smaller AREA and clearly higher
PD because most of these forests were formerly used as pastures. Riparian vegetation covered
only smaller areas, but showed a relatively high PD because many small patches and strips of
remnant riparian forests were present along the riversides.
The expansion of oil palm plantations causes considerable changes in the landscape matrix.
Pasture-dominated parts were richer in ecologically valuable elements such as live fences and
riparian vegetation, while within and along oil palm plantations mainly ecologically futile
elements such as roads and drainage ditches were found. Compared to pastures plantations had a
bigger AREA, but lower PD which reflects that they are labor-intensive permanent cultures of
great extend. The land use map (see Figure 1) shows that, conversely to pastures, oil palm
plantations were never divided and scarcely bordered by live fences. Hence, the expansion of
these plantations involves the risk of a simplification of landscapes and the loss of small natural
landscape elements in agricultural areas. This can lead to a significant reduction or shift of the
biodiversity in tropical ecosystems affected by oil palm plantations.
Oil palms are a globally rapidly expanding crop which has already replaced large areas of
natural forest in many tropical countries such as Malaysia or Indonesia and this progress is still
going on. These plantations entail many other problems such as habitat fragmentation, pollution,
loss of biodiversity and soil destruction. Because oil palms are unsuitable habitat for most forest
species they can act as severe barrier to animal movement (Fitzherbert et al. 2008). To maintain
the exchange of plants and animals between the forest areas surrounding the village La Gamba,
the conservation of live fences and other natural habitats is of great importance. As the mean
patch area of pastures was relatively big (2.52 ha) and the density of live fences was rather low
(20.0 m per ha farmland) more live fences could be established by dividing pastures into smaller
paddocks (Höbinger 2010). This measure would improve the connectivity of forest patches,
increase the tree cover within farmland, and provide a high conservation value of the
agricultural landscape mosaic in its unconnected gallery forests (Seaman and Schulze 2009).
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