Modelling mutual interactions between soil structure and soil biological communities.

Habitat structure is a key factor controlling the structure of ecological communities. For example, complex habitat structure may increase species number, minimise competition and facilitate the retention of nutrients. Alteration and disturbance of habitat structure may thus negatively affect biodiversity. Soil is an extremely complex and highly structured environmental matrix. Soil structure, defined as a distribution of aggregate/pore space of different sizes, can thus be a major control of soil biological communities, which are for example highly structured in their size distribution. Soil organisms, however, also affect and modify soil structure, and for many organisms the soil habitat structure is thus not just a condition to which they have to adapt but, rather, an environmental feature they also affect. In this talk, I discuss all these aspects from a community ecology point of view and with an emphasis on statistical and dynamical models that soil ecologists are trying to develop to describe and predict the mutual interactions between soil structure and biological communities. I will focus on the different rates at which soil structure affects soil organisms and vice versa, to emphasise that the temporal scales at which we have to measure the two parts of this mutual feedback (i.e. soil structure -> biota vs. biota -> soil structure) are very different, and also variable in space and time.