Abstract:
Habitat loss and fragmentation are the main drivers of biodiversity loss in terrestrial ecosystems, particularly
in the tropics. Fragmented habitats can interfere with organism dispersion, population persistence and
ecosystem functions but empirical studies report wide variation in the sensitivity of organisms and functions to
fragmentation and the mechanisms operating behind observed responses remain poorly understood. In this
study we examined the effects of forest fragmentation on the colonization of artificial treeholes in
northwestern Costa Rica by measuring the responses at the community level. We explored four potential
mechanisms driving differences in macroinvertebrate communities between continuous and fragmented
forests: dispersal limitation, microclimate changes and bottom up or top down effects. Macroinvertebrate
community composition differed significantly between continuous forests and forest remnants but not in the
predicted direction. Our results suggest that treeholes in fragmented forest contain higher abundance of
detritivores and experience changes in predator species identity consistent with increased nutrient input and a
potential relaxation of predation pressure in small forest remnants. An overall resilience of treehole
communities to forest fragmentation is interpreted with care as time-delayed responses to fragmentation
continue to be a possibility. These findings advance our understanding of the response of biological
communities to forest fragmentation and emphasize the value of preserving even small forest remnants for
biodiversity conservation.
