How does the transformation of Cerrado vegetation into exotic pastures affect insect communities? A meta-analysis

Cerrado is the largest and most biodiverse savannah worldwide. However,
only a reduced amount of this ecosystem is conserved, and in the last
decades, the vast agricultural expansion resulted in the substitution of
native vegetation for exotic pasturelands. Insects are key components for
both native and exotic ecosystems in Cerrado, performing critical
functions for ecosystem maintenance. Our goal was to evaluate how the
transformation of natural Cerrado into cattle pastures (exotic pastures)
affects the insect communities in this biome. We conducted a meta-analysis
using data on species richness and abundance data of insect assemblages
from conserved Cerrado and exotic pastures. The analysis was based on a
set of 25 scientific articles. Fourteen studies focused on Coleoptera and
nine on Hymenoptera. Conserved Cerrado encompassed a higher species
richness of insects than exotic pastures, but their abundance did not
differ between these two habitats. However, dung beetle abundance
increases significantly in disturbed Cerrado over time. Synanthropic
species that thrive in altered environments could be masking the actual
decline in abundance of species sensitive to environmental disturbances
provoked by exotic pastures. Our results highlight the consequences of the
structural homogenization of the Cerrado into cattle pastures. That is,
despite having a similar open-canopy vegetation structure, this land-use
change leads to a significant loss of insect species, resulting in a
drastic simplification of insect communities. This study reinforces the
importance of maintaining native Cerrado patches in order to maintain
diverse and functional ecosystems in this region.