Fagan, B.; Martins, I. S.; Pitchford, J.; Stepney, S.; Thomas, C. D.

Humans have dramatically altered the Earth's 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.