Final Report Summary - SENSE (Structure and Ecological Niche in the Soil Environment)
SENSE (Structure and Ecological Niche in the Soil Environment) aimed to discover the process affecting soil animal diversity and how soil biodiversity affects ecosystem stability and function. Thanks to a number of international collaborations, SENSE was able to extend the study of these processes to microbial groups and the whole soil food web indeed. One of the major conclusions is that the effect of environmental variation on the structure of soil biological communities is certainly significant but often not sufficient to explain patterns of species coexistence. Environmental factors (e.g. soil moisture, pH) usually explain a low amount of the variation observed in these communities while at the same time there is nonrandom spatial variation in these communities, even if this variation cannot be explained by spatial variation in environmental properties. This general result applies to organisms as different as nematodes, arthropods and fungi and is thus very general. Consequently, other factors must drive the distribution of soil species and the research conducted by SENSE has demonstrated that biotic interactions, which are extremely difficult to quantify in soil, are the missing factor in explaining soil biodiversity. SENSE has collected evidence from temperate grassland and forests to soil in Antarctic polar deserts that show the strong and often neglected role of trophic interactions and resource partitioning in explaining how soil species come together to form complex biotic communities and food webs. For example, a stable isotope analysis of the natural abundance of N and C coupled with an analysis of patterns of species co-occurrence has revealed that different species of mites in forests often diverge in terms of trophic position if they coexist in the same local community. Species that are in the same trophic position may also segregate to live in different local communities and thus avoid competition. These clear patterns, which have been collected and quantified for the first time, suggest that trophic differentiation and resource partitioning play a major role in explaining the extremely high biodiversity observed in soil.
Thanks to an extensive analysis of the evolution of trophic position, body size and shape in a major group of soil animals (oribaitd mites) SENSE has also shown for the first time that trophic diversification in soil animals has happened very early and multiple time over the more than 400 million of years of biotic evolution in soil. This evolutionary dimension is important to explain how species have evolved to coexist nowadays and how the structure of the whole soil food web has evolved. SENSE has shown that Oribatid mites, which are central to the trophic structure of soil food webs, diversified in the early Paleozoic, resulting in complete soil food webs by the Devonian. The evolution of body size, form, and an astonishing trophic diversity in oribatid mites demonstrate that soil food webs were fully functional already in the Silurian, facilitating the establishment of higher plants and the formation of terrestrial ecosystems in the Devonian and Carboniferous. Since then, the fundamental structure of soil food webs has persisted through the Mesozoic, supporting the establishment of flowering plants and, eventually, the current soil systems
In this context, a major question of SENSE was to unravel the relationship between stability and diversity in large food webs. SENSE identified the food web factors (e.g. species number, intensity of trophic interactions) affecting the stability of large soil ecological networks. To do so, SENSE analyzed a novel set of soil food web models that accounted both for realistic levels of species richness and the most recent views on the functional structure of these food webs. These new, very recent views are supported by growing empirical data on a number of trophic and functional interactions that have been overlooked or underestimated in the past. SENSE found that the architecture of how trophic interactions are distributed between species (i.e. the topological structure of the network) combined with the strong correlations between the intensity of trophic interaction stabilised food webs, even at the high levels of richness (several hundred species) that are typical of the food webs found in association with the root of a single grass plant. These finding also support the hypothesis that patterns in animal body size distribution is a fundamental stabilising factor of food webs, with body size increasing from lower to higher trophic levels in soil food webs. The evolution and diversification of body size and shape can thus be one of the fundamental forces that has driven the emergence and persistence of soil food webs over deep time and from local to very broad scales.
Thanks to an extensive analysis of the evolution of trophic position, body size and shape in a major group of soil animals (oribaitd mites) SENSE has also shown for the first time that trophic diversification in soil animals has happened very early and multiple time over the more than 400 million of years of biotic evolution in soil. This evolutionary dimension is important to explain how species have evolved to coexist nowadays and how the structure of the whole soil food web has evolved. SENSE has shown that Oribatid mites, which are central to the trophic structure of soil food webs, diversified in the early Paleozoic, resulting in complete soil food webs by the Devonian. The evolution of body size, form, and an astonishing trophic diversity in oribatid mites demonstrate that soil food webs were fully functional already in the Silurian, facilitating the establishment of higher plants and the formation of terrestrial ecosystems in the Devonian and Carboniferous. Since then, the fundamental structure of soil food webs has persisted through the Mesozoic, supporting the establishment of flowering plants and, eventually, the current soil systems
In this context, a major question of SENSE was to unravel the relationship between stability and diversity in large food webs. SENSE identified the food web factors (e.g. species number, intensity of trophic interactions) affecting the stability of large soil ecological networks. To do so, SENSE analyzed a novel set of soil food web models that accounted both for realistic levels of species richness and the most recent views on the functional structure of these food webs. These new, very recent views are supported by growing empirical data on a number of trophic and functional interactions that have been overlooked or underestimated in the past. SENSE found that the architecture of how trophic interactions are distributed between species (i.e. the topological structure of the network) combined with the strong correlations between the intensity of trophic interaction stabilised food webs, even at the high levels of richness (several hundred species) that are typical of the food webs found in association with the root of a single grass plant. These finding also support the hypothesis that patterns in animal body size distribution is a fundamental stabilising factor of food webs, with body size increasing from lower to higher trophic levels in soil food webs. The evolution and diversification of body size and shape can thus be one of the fundamental forces that has driven the emergence and persistence of soil food webs over deep time and from local to very broad scales.