Simulating Competition and Coexistence between Plant Functional Types in a Dynamic Vegetation Model

Abstract

The global distribution of vegetation is broadly determined by climate, and where bioclimatic parameters are favorable for several plant func- tional types (PFTs), by the competition between them. Most current dynamic global vegetation models (DGVMs) do not, however, explicitly simulate inter- PFT competition and instead determine the existence and fractional coverage of PFTs based on quasi-equilibrium climate-vegetation relationships. When com- petition is explicitly simulated, versions of Lotka-Volterra (LV) equations developed in the context of interaction between animal species are almost always used. These equations may, however, exhibit unrealistic behavior in some cases and do not, for example, allow the coexistence of different PFTs in equilibrium situations. Coexistence may, however, be obtained by introducing features and mechanisms such as temporal environmental variation and distur- bance, among others. A generalized version of the competition equations is proposed that includes the LV equations as a special case, which successfully models competition for