Oral

IAMAS

JMP07 - Past climate changes and their relevance for the future

Simulating terrestrial mammals (including humans) in the context of the changing climate climate of the Pleistocene

Here we present a new dynamical and spatially-resolved model that resolves 2171 mammal species (including early humans) explicitly along with their interactions. The core of the model is a set of coupled reaction diffusion equations with competition and predation terms included. Key parameters of the model are estimated from allometric body mass scaling relationships. The carrying capacities of the species are calculated from habitat suitability models and estimates of regionally available food resources which for carnivores are estimated from a predator/prey matrix and for herbivores from the net primary productivity of vegetation. Both, the habitat suitability model and the net primary productivity depend at each grid point on a 1x1 degree mesh on climate input parameters, which are obtained from a realistic transient paleo-climate model simulation covering the last ice age cycle. Our presentation focuses on the impact of Milankovi? cycles on mammal biomass, species richness and diversity, and trophic relationships. We will showcase, in particular, the effect of humans as a new and emerging Late Pleistocene top predator in the system and quantify its influence on megafauna biomass and ecosystem stability. For humans, we introduce a new stochastic equation for cumulative culture, which boosts carrying capacity. In additional sensitivity experiments, we wil demonstrate that human cultural evolution likely accelerated the Late Pleistocene megafauna extinctions.