COS 49-4: Allometry of soil food webs and C:N:P stoichiometry
Christian Mulder, Dutch National Institute for Public Health and Environment, Daniel C. Reuman, Rockefeller University, and Joel E. Cohen, Rockefeller University and Columbia University.
Allometry integrates the biological and physicochemical constraints that occur in terrestrial ecosystems. We investigated the relationships between body-mass and numerical abundance of all invertebrates occurring under 15 organic pastures sown with N2-fixing legumes, 10 mature grasslands and 10 heathlands in The Netherlands. Here we show how food webs respond to variations in nutrient limitation and microbial resources. Log-linear models, in particular, describe how the allometric slopes of food webs reflect soil C:N:P stoichiometry. The nitrogen-to-phosphorus ratio explains most trends, among others the number of trophic links and the contributions of micro– and mesofauna to the food-web structure. We conclude that soil P-deficiency affects the consumer–resource body-mass ratios, as our results support a different response of invertebrates to the supply of nutrients. This study can help bridge the gap between community structure and function, and may inform improved agricultural policy and restoration ecology.