Individual and combined effects of global change drivers on biodiversity

All across the world, species’ populations and the biodiversity of ecological communities are changing in complex ways. Against a backdrop of accelerating global change, a critical research step is to disentangle the sources of the heterogeneous patterns of population and biodiversity change. To contribute to this challenge, we have integrated recent compilations of long-term population (Living Planet Database) and biodiversity (BioTIME Database) time-series with maps of global change and information on species’ habitat preferences, phylogeny and threats.

Across populations, we found that 15% of populations were declining, 18% were increasing, and 67% showed no net changes in abundance over time. Against a backdrop of no biogeographic and phylogenetic patterning in population change, we uncovered a distinct taxonomic signal. Amphibians were the only taxa that experienced net declines in the analysed data, while birds, mammals and reptiles on average became more abundant over time. Across ecological communities, we found forest loss leads to both positive and negative responses of populations and biodiversity across over 2000 sites, with population declines most pronounced during the periods of peak forest loss and temporal lags extending up to half of a century. In the Arctic, we found hotspots of biodiversity in warmer microclimates.

Global change drivers, such as land-use change, climate change, pollution and invasion pressure, can influence populations and ecological communities in contrasting ways. When populations and ecological communities are simultaneously exposed to multiple types of environmental alterations, our preliminary findings suggest that there are both antagonistic (the drivers cancel each other out, producing no net biodiversity changes), and synergistic effects (the drivers amplify each other’s effects). Accounting for these heterogeneous and sometimes hidden responses to global change drivers is key when scaling from local impacts of human activities to global scale biodiversity patterns and projections of human impacts on Earth’s biota. 

Daskalova, G.N., Myers-Smith, I.H., Bjorkman, A.D., Blowes, S.A., Supp, S.R., Magurran, A., Dornelas M. (2018) Forest loss as a catalyst of population and biodiversity change. (bioRxiv) 

Daskalova, G.N., Myers-Smith, I.H. & Godlee, J.L. (2018) Rarity and conservation status do not predict vertebrate population trends. (bioRxiv)