Major biases and knowledge gaps on fragmentation research in Brazil: implications for conservation

Abstract

Habitat loss and fragmentation are among the main threats to global biodiversity and ecosystem services. However, major research biases and knowledge shortfalls in some geographical regions, taxonomic groups and responses studied are recurrent in fragmentation-related research. Therefore, detecting these biases and associated gaps is crucial to steer future research efforts and to guide applicable conservation policies. Here we conducted an exhaustive literature review to evaluate biases on fragmentation research across biomes, taxonomic groups, species responses and fragmentation metrics in Brazil. Overall, we analysed 716 papers, comprising a database with 26 taxonomic groups and 1173 cases studied across the six Brazilian biomes. In general, we observed that fragmentation-related research was biogeographically biased towards forest biomes. Specifically, the Atlantic Forest, the most populated and deforested Brazilian biome, comprised the highest number of studies (63%), while non-forest biomes were largely underrepresented. We also detected a high positive relative taxonomic bias for birds and mammals, while many insect taxa were disproportionately underrepresented in the literature. Altogether, assemblage-level species responses (abundance, diversity and richness) comprised 72% of study cases. Moreover, fragment size was clearly the most considered metric in the studies (43%) followed by habitat quality and edge effects. Our findings indicate major information deficits with regard to fragmentation-related research among taxonomic groups and amongst biomes in a megadiverse country. Therefore, we suggest that fragmentation research conducted in Brazil needs to consider undersampled taxa and to be urgently extended to increasingly degraded non-forest biomes in order to avoid inappropriate inferences.