Introduced annuals mediate climate-driven community change in Mediterranean prairies of the Pacific Northwest, USA

Aim: How climate change will alter plant functional group composition is a critical question given the well-recognized effects of plant functional groups on ecosystem services. While climate can have direct effects on different functional groups, indirect effects mediated through changes in biotic interactions have the potential to amplify or counteract direct climatic effects. As a result, identifying the underlying causes for climate effects on plant communities is important to conservation and restoration initiatives.

Location: Western Pacific Northwest (Oregon and Washington), USA.

Methods: Utilizing a three year experiment in three prairie sites across a 520 km latitudinal climate gradient, we manipulated temperature and precipitation and recorded plant cover each spring. We used structural equation models to examine how abiotic drivers (i.e., temperature, moisture, and soil nitrogen) controlled functional group cover, and how these groups in turn determined overall plant div...