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| The conversion of forest to agriculture across the world’s tropics, and the limited space for
protected areas, has increased the need to identify effective conservation strategies in
human-modified landscapes. Isolated trees are believed to conserve elements of ecological
structure, providing micro-sites for conservation in matrix landscapes, and facilitating seed
dispersal and forest restoration. Here we investigate the role of isolated Ficus trees, which
are of critical importance to tropical forest ecosystems, in conserving frugivore composition
and function in a human-modified landscape in Assam, India. We surveyed the frugivorous
birds feeding at 122 isolated Ficus trees, 33 fruit trees, and 31 other large trees across a
range of 32 km from the nearest intact forest. We found that Ficus trees attracted richer and
more abundant assemblages of frugivores than the other tree categories. However, incidence
function estimates revealed that forest specialist species decreased dramatically
within the first kilometre of the forest edge. Despite this, species richness and functional diversity
remained consistent across the human-modified landscape, as habitat generalists
replaced forest-dependent frugivores, and accounted for most of the ecological function
found in Ficus trees near the forest edge. We recommend that isolated Ficus trees are
awarded greater conservation status, and suggest that their conservation can support ecologically
functional networks of frugivorous bird communities. | |
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