Habitat loss and fragmentation in Chaco forests: a review of the responses of insect communities and consequences for ecosystem processes

Abstract

Habitat loss and fragmentation are landscape transformations with profound impacts on biodiversity. Insects are particularly affected by these processes, with consequences for ecosystem services. In the Neotropics, the Chaco forest is one of the largest phytogeographic regions and has suffered critical deforestation rates in recent decades. For 20 years, we have studied the impact of these modifications on insect communities in Córdoba, Argentina, and the interaction between forests and adjacent crops. Here, we review 25 empirical studies of the influence of fragment area, forest cover, and edge habitats on different insect functional groups, ecological processes, and ecological networks in fragmented Chaco forests in central Argentina. Small fragments and landscapes with low proportions of forest cover were generally linked to impoverished insect communities across most functional groups. Fragment area reductions negatively affected above-ground processes such as herbivory and parasitoidism, whereas leaf litter decomposition and most network parameters were not affected. Edge effects were variable, favoring some insect groups (i.e., ground-dwelling arthropods and parasitoids) and parasitoidism rates. Moreover, intense insect movement between forests and crops increased ecosystem service provision near the forest. Our results indicate that fragmentation of Chaco forests has clear implications for insect communities and ecosystem services. Maintaining forest remnants and promoting native forest plantations should be prioritized to guarantee insect biodiversity conservation.