Agriculture erases climate‐driven β‐diversity in Neotropical bird communities

Abstract

Earth is experiencing multiple global changes that will, together, determine the fate of many species. Yet, how biological communities respond to concurrent stressors at local-to-regional scales remains largely unknown. In particular, understanding how local habitat conversion interacts with regional climate change to shape patterns in b-diversity-differences among sites in their species compositions-is critical to forecast communities in the Anthropocene. Here, we study patterns in bird b-diversity across land-use and precipitation gradients in Costa Rica. We mapped forest cover, modeled regional precipitation, and collected data on bird community composition, vegetation structure, and tree diversity across 120 sites on 20 farms to answer three questions. First, do bird communities respond more strongly to changes in land use or climate in northwest Costa Rica? Second, does habitat conversion eliminate b-diversity across climate gradients? Third, does regional climate control how communities respond to habitat conversion and, if so, how? After correcting for imperfect detection, we found that local land-use determined community shifts along the climate gradient. In forests, bird communities were distinct between sites that differed in vegetation structure or precipitation. In agriculture, however, vegetation structure was more uniform, contributing to 7%-11% less bird turnover than in forests. In addition, bird responses to agriculture and climate were linked: agricultural communities across the precipitation gradient shared more species with dry than wet forest communities. These findings suggest that habitat conversion and anticipated climate drying will act together to exacerbate biotic homogenization.

Annual temperature variation influences the vulnerability of montane bird communities to land‐use change

“…To quantify differences between forest and agricultural bird communities within a region, we calculated the Euclidean distance of each forest community in a given region to the centroid of all agricultural communities in that region (Karp et al 2018). The Cartesian coordinates for each forest community (and the centroid for the agricultural communities) were derived from the locations of these communities in multivariate space (i.e.…”

“…The adaptation of species to locally prevalent environmental conditions is likely to influence their sensitivity to land-use change, because habitat modification alters the abiotic environment, especially the thermal environment. Indeed, birds adapted to dry Neotropical forests have been found to be more tolerant of the conversion of forest to agriculture (Frishkoff et al 2016, Karp et al 2018, and low thermal tolerances in reptiles and amphibians are associated with greater sensitivity to habitat change (Frishkoff et al 2015). Further, forest canopies buffer the understorey against thermal extremes, leading to lower temperature variation within forests than in anthropogenically modified habitats (DeFrenne et al 2019).…”

Anthropogenic disturbance homogenizes seagrass fish communities

“…In addition, spatial autocorrelation is an important determinant of beta-diversity that should be considered in analyses of biotic homogenization (e.g., Ferenc et al, 2014;Karp et al, 2012;Karp et al, 2017;Leprieur, Beauchard, Hugueny, Grenouillet, & Brosse, 2008), and we conducted two within-region sensitivity analyses to verify beta-diversity comparisons after controlling for spatial autocorrelation. Some regions were surveyed by the same field team, whereas others were surveyed by independent teams.…”

Integrating over uncertainty in spatial scale of response within multispecies occupancy models yields more accurate assessments of community composition

“…For empirical analyses -particularly if there are specific hypotheses regarding how species parameters covary -adjusting the presented ssMSOM to accommodate these interspecific covariances is recommended (Karp et al 2018). We do not do this here because the estimation procedure significantly adds to computational time, because we do not simulate these covariances, and because estimation of covariances is unnecessary to demonstrate the functionality of integrated scale selection within occupancy models.…”

“…Spatial forest cover data for simulation and analysis came from a recent study of how local and landscape-level habitat conversion affects community composition in northwestern Costa Rica (Karp et al 2018). Spatial forest cover data for simulation and analysis came from a recent study of how local and landscape-level habitat conversion affects community composition in northwestern Costa Rica (Karp et al 2018).…”