Short and long-term consequences of Habitat Transformation for Biodiversity

Abstract

Humans have dramatically altered the Earths surface and the distributions of species, but coherent patterns distinguishing cause from effect are hard to discern. Community composition and ecosystem function can change as rapidly as local land-use, and we lack robust principles to understand the outcomes of these changes. This hampers assessments of ecosystem collapse or robustness. Here we create theoretical ecosystems using a community assembly framework in which we manipulate environmental filtering via both the local land-use and species traits. This isolates the impacts of environmental filtering into land-use, land-use change, and species trait diversity, allowing us to extract clear patterns and relationships. First, we identify the paradox of maladaptation. We find that better land-use adaptation reduces species richness in the habitat but increases species abundance and ecosystem complexity. Increasing diversity amongst species traits reduces species richness via a similar mechanism. Additionally, whilst over long time scales there is very little effect of land-use change, on very short time scales there is a predominantly negative effect on richness. Together, this highlights the need for careful facilitation and management of land-use change in the face of an ever-changing world. Author SummaryHumans have dramatically altered the Earths surface, primarily through land-use change and changing where species are and where they can go. This has resulted in extinctions, immigration, and, most of all, variation in where species end up. Here, we use simulations to compare how habitat, habitat change, and species adaptations create variation in outcomes due to land-use change. First, we show that while adaptation is good for individual species, it also reduces the overall diversity (number of species) of the ecosystem; similarly, well-adapted species out-perform and exclude less well-adapted species, also lowering the resulting diversity of the ecosystem. Secondly, we find that habitat change has different short- and long-term consequences. Habitat change can create dramatic declines on short time scales due to the different pressures experienced by species based on which species they eat (trophic level). But, on long time scales it has very little effect on diversity, as communities acquire new species adapted to the new conditions. We conclude that short-term declines in diversity due to recent or ongoing habitat change could be eased by helping well-adapted species to immigrate to form ecological communities in the new environment.