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fragments. Moreover, small forest patches in severely-fragmented landscapes may
be strongly impoverished in terms of the number of species and individuals with
particular pollination systems (e.g. pollination by bats, birds, non-flying mam-
mals, Sphingids) and may be dominated by tree species pollinated by generalists.
Finally, strategies that are more dependent on long-distance pollen movement
and animal-mediated services, such as self-incompatibility, may be negatively af-
fected. These statements are supported by the fact that the differences we found
between fragments and control plots could not be explained by soil type or the
relative spatial position of the plots in the landscape. Although the distribution of
tropical trees has been found to be influenced by variation in soil types [52], [67],
there is no evidence that this also influences the spatial distribution of ecological
groups (based on reproductive traits, regeneration strategy, etc.) in terra firme
forests [8], [68].
An increasing body of evidence has shown that as fragments become older,
tree assemblages become drastically altered [12], [69]-[71]. Plant assemblages in
small fragments (<10 ha) and forest edges are impoverished (scores of alpha diver-
sity reduced by a half ) and biased in taxonomic and ecological terms towards pio-
neer species. These patch-level findings suggest that fragmented landscapes tend
to retain just a small subset of species from the original biota. Despite the recent
findings on this topic, our study is one of the first to document a marked shift on
the signature of tree assemblages inhabiting a fragmented landscape with respect
to the frequency of reproductive-related traits and its functional diversity. Simi-
lar results were reported by Chazdon et al. [72] for tree assemblages in second-
growth, logged, and old-growth forests in Costa Rica. They found lower relative
abundance of mammal-pollinated trees in second-growth forests in comparison
to old-growth ones, as well as a higher relative abundance of hermaphroditic trees
in second-growth forests. In addition, Murcia [27] suggested fragmented forests
tended to have an increased frequency of self-compatible hermaphrodites at the
expense of other sexual systems. Our findings are consistent with these results,
as well as recent ones indicating self-incompatible systems are more negatively
affected than self-compatible ones following habitat loss and fragmentation [12],
[25], [29].
Two fragmentation-related processes may be the principal mechanisms driv-
ing the changes in reproductive traits and functional diversity we observed: 1)
the proliferation of pioneer species with a concomitant decline in the abundance
of shade-tolerant trees and 2) depressed population sizes of animal pollinators,
which over time led to changes in tree abundance in forest fragments. In tropi-
cal forests, myriad processes triggered by the creation of forest edges promote a
proliferation of short-lived pioneers [8] and the local extirpation of shade-tolerant
trees, including canopy and understory species [10], [19], emergent trees [73]
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