Volume 194, February 2016, Pages 176–183
Open Access
Highlights
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- We compared oil palm sites with and without adjacent forest fragments.
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- We surveyed dung beetle and ant communities and function at each site.
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- There were limited spillover effects of dung beetle species from forest to oil palm.
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- There were no spillover effects for ant species or either function.
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- Restricted dispersal emphasises the importance of habitat corridors for insects.
Abstract
The
world's forested landscapes are increasingly fragmented. The effects of
fragmentation on community composition have received more attention
than the effects on ecological processes, particularly in the tropics.
The extent to which populations from forest fragments move (spillover)
into surrounding agricultural areas is of particular interest. This
process can retain connectivity between populations and alter the rate
of beneficial or detrimental ecological functions. We tested whether
riparian forest fragments (riparian reserves), are sources of two
functionally important invertebrate groups (dung beetles and scavenging
ants) within oil palm plantations in Malaysia. We also assessed whether
forest fragments enhance rates of associated ecosystem functions (dung
and bait removal). We found that oil palm sites with and without
adjacent riparian reserves had similar overall beetle and ant
communities and functional rates. However, dung beetle species richness,
abundance and diversity declined with distance from a riparian reserve,
providing evidence for a weak spillover effect. In addition, dung
beetle community metrics within a riparian reserve predicted
corresponding values in adjacent oil palm areas. These relationships did
not hold for dung removal, ant community metrics or bait removal. Taken
together, our results indicate that although riparian reserves are an
important habitat in their own right, under the conditions in which we
sampled they have a limited role as sources of functionally important
invertebrates. Crucially, our results suggest that contiguous habitat
corridors are important for maintaining connectivity of invertebrate
populations, as forest dependent species may not easily be able to
disperse through the agricultural matrix.
Keywords
- Ecosystem function;
- Forest fragments;
- Tropical agriculture;
- Dung beetles;
- Ants;
- Borneo
