There has been in the last decade enormous developments in the field of spatial ecology. It has been greatly influenced by the usual concerns of community ecologists, such as species coexistence, community stability and the relationship between diversity and ecosystem functioning. In parallel was developed another perspective, the one of landscape ecology, essentially extending ecosystem ecology to larger scales. The natural extension of these theories is the metaecosystem concept. The meta -population and –community theories have been concerned with the dispersal of populations and communities. Under the meta-ecosystem perspective, the question arising is how spatial flows of materials (energy, nutrients and organisms) affect community dynamics and ecosystem functioning at the regional scale. In this study, we look for the first time at how the spatial flows of a limiting nutrient through direct (inorganic) and indirect (detritus) pathways influence the assemblage of species in a competitive and spatially structured ecosystem.
Results/Conclusions
We first study a model of nutrient, plant and detritus dynamics in a static space and show that regional properties of the landscape have considerable impacts on the local dynamics of a simple ecosystem model. Under some well defined circumstances, increasing the spatial occupancy results in a net positive interaction on species invasibility because it increases more the inputs via the detritus flows than the outputs via direct resource diffusion. In a second step, we expand this model by coupling the local dynamics to the dynamics of spatial occupancy with an adaptation of the Levins’ metapopulation model. This allows us to reveal strong feedback loops between local and regional dynamics mediated by resource flows. Local resource dynamics impacts colonization abilities through an effect on local productivity. In return, regional dynamics impacts the local dynamics through an effect on resource redistribution. Subtle indirect interactions emerge from this coupling, both competitive and facilitative. We finally show how the relative importance of inorganic versus organic nutrient flows affects some essential patterns such as the shape of the competition-colonization trade-off, the successional sequence of species and the diversity-productivity relationship. In conclusion, the metaecosystem concepts provides novel fundamental insights into the dynamics of spatial ecosystem functioning, from local to regional scales, and valuable predictions on the consequences of altering the basic processes of resource spatial flows on community dynamics.
