How spatial structure determines the dynamical regimes of ecosystems
Identifying the drivers of ecosystem and population dynamical behavior is a fundamental aspect of ecology. In a spatially explicit context, the basic ingredients to consider are the spatial structure of the landscape, the local dynamics at play, and the dispersal and diffusion which mediates between the former two. Numerous studies has looked at each of these components separately, but little is known on the interplay between them. Missing has been a more integrative approach, able to map and identify the possible dynamical regimes in the system, and in particular its response to perturbations.
I will focus my talk on a simple, yet relatively general, scenario: the recovery of a homogeneous metapopulation from a single, spatially localized pulse disturbance. We find that the response can take one of three forms, each representing one of three dynamical regimes: Isolated, Interplay and Mixing. Using dimensional analysis we can predict the transition points between these regimes, and how these change with basic system properties such as its total area and the nonlinearities of local dynamics. This enables us to address pertinent issues in ecology, such as habitat fragmentation, synchrony-induced extinctions, and mechanisms of biomass productivity in metacommunities.
I will finish the talk by briefly presenting a few extensions of this work. In particular, a possible indicator of bistability based on the spatial extent of disturbances, the spatial aggregation of disturbances when their frequency is high, and the spatial patterns of ecosystem engineers along an environmental gradient.