Plant diversity-climate interactions from a modeling perspective

Mounting evidence from field observations has shown that high functional diversity is associated with strong ecosystem resilience and stability. However, plant ecology studies have focused on the passive response of global ecosystems to climatic changes while the impacts of plant-functional diversity on climate including its feedback are seldom addressed. Moreover, state-of-the-art climate models are insufficient to address such topics. Their land component models cover only a restricted range of present-day plant features, so that adaptation at the sub-grid scale is ignored. Based on a process-based plant functional trade-off scheme developed by Kleidon and Mooney (2000), we have set up a new vegetation model JeDi-BACH into the land component of the ICON-Earth System Model (ICON-ESM). The advantage of this new model is that the representation of global vegetation is an emergent outcome of environmental filtering following several well-known fundamental functional trade-offs that link plant functions to abiotic and biotic attributes. In such a way, plants dynamically adjust to the changing environment and meanwhile modify climate. With this new model, we present a series of sensitivity studies investigating the effect of plant trait diversity on the coupled vegetation-climate system in a coupled land-atmosphere setup. We found that high plant diversity ecosystems tend to stabilize terrestrial climate in a high water-turnover state, leading to a wet and cool climate. The enhancement in evapotranspiration with increasing diversity found in our study is consistent with the BEF (Biodiversity-Ecosystem Functioning) relationship derived from the field studies. Our modeling results demonstrate the importance of the "biodiversity-climate feedback" and highlight the role of plant functional diversity in shaping a robust climate.

Kleidon, A. and Mooney, H. A.: A global distribution of biodiversity inferred from climatic constraints: Results from a process-based modelling study, Glob. Chang. Biol., 6(5), 507–523, doi:10.1046/j.1365-2486.2000.00332.x, 2000.