A predator-prey model for Pleistocene global vegetation and wildfire dynamics

Global vegetation patterns are not only determined by climate, water availability, and soil conditions, but also by the dynamics of seed/plant dispersal, competition, herbivory, and fire. To account for these processes, we developed a new dynamical vegetation model (ICCP Global Vegetation Model) based on coupled 2D Lotka-Volterra equations that also includes plant and fire diffusion. The model simulates the area fraction of three plant functional types (grass, shrubs, and trees) and fire. Fire is introduced as a stochastic predator that "feeds" on available burnable carbon and emerges when climate conditions are suitable. The climate dependence of the competing plant functional types is calculated from a species distribution model that calculates habitat suitability from key climatic parameters. The model can also account for herbivore grazing, which is estimated from the ICCP Global Mammal model. In this presentation, we will compare transient Pleistocene simulations conducted with the ICCP Global Vegetation Model with Biome4 model simulations and time-slice vegetation reconstructions for the mid-Holocene (6 ka) and the Last Glacial Maximum (21 ka).