Biodiversity dynamics in urban areas under changing land-use

Urbanisation has strong effects on biodiversity, with varying impacts between species groups. Likewise, species turnover is expected along an urbanisation gradient. Using species occurrence records from online databases and detailed land-cover maps, we here test the effects of land-cover and land-cover change on species composition along an urban-rural transition zone. We show that threatened species are primarily found in habitats with little human impact, whereas the number of alien species does not vary between land-covers but depends on taxa and spatial correlation. Species with contrasting functional trait syndromes respond differently to increasing levels of urbanisation, and changes in land-cover over time affects species composition and –turnover. This indicates how urbanisation functions as an ecological filter. Conclusively, land-cover variables can be used to make predictions on species richness within overarching species groups. We recommend that biodiversity management agencies ensure limited disturbance of native ecosystems to favour native, locally adapted species, and closely monitor urban areas to mitigate the introduction and spread of alien species.