Fire and logging alter plant-frugivore interactions in Amazonia over
decadal time-scales
Abstract
Amazonian forests are vulnerable to a wide range of human threats, such
as selective logging and forest fires. The capacity of Amazonian forests
to recover from human-disturbances depends, among other factors, on the
persistence of frugivory interactions leading to essential ecological
functions, like seed dispersal. Although important, little is known
about frugivory interactions in the Amazonian forests. Most studies
focus on a single or a limited set of similar species; neither studies
include both arboreal and terrestrial frugivores. Moreover, most studies
have not studied the impact of human-disturbances. We investigated the
impacts of selective logging and forest fires on frugivory interactions
in Amazonian forests. We sampled interactions at the community level,
surveying arboreal and terrestrial frugivores across 17 forest transects
with variable disturbance histories. We found that undisturbed forests
held a significantly higher richness of species and interactions
distinct from those of interactions human-disturbed forests. Logged
forests burned 17 years previously held substantially lower richness of
species and interactions, and the interaction composition was almost
entirely dissimilar to those of undisturbed forests. Logged (unburned)
and logged forests burned three years previously also differed
substantially in their frugivory interaction composition, but overall
richness and frugivory interactions richness was similar. However,
neither selective logging nor forest fires changed the structural
properties of frugivory networks, which are highly modular, moderately
specialised and poorly connected and nested. β-diversity of plant and
frugivore species as well as their interactions was high among all
transects, mainly due to the high spatial turnover. Our study provides
the first empirical evidence of the negative effects of fires combined
with selective logging on frugivory interactions in tropical forests,
highlighting the long time-scales required to evaluate impacts and
reestablish ecological processes.