Biotic interactions and trait-based ecosystem functioning in soil

Abstract

Recent emphasis on ecosystem services as a framework to evaluate ecosystems and to promote their sustainable use has drawn attention to how organisms contribute to the delivery of services. Soil attributes and biotic interactions play important roles in ecological processes (e.g. soil formation, nutrient turnover, carbon sequestration and transformation) and, consequently, in the related delivery of ecosystem services. Therefore, understanding how soil organisms interact and how they respond to environmental conditions is fundamental to preserve soil functioning and provide a meaningful assessment of ecosystem services. Functional traits determine individual responses to pressures and their effects on ecosystem functioning hence, investigating soil ecosystems from a trait-based perspective offers an interesting opportunity to link the functional responses of the organisms to environmental pressures and to give insight into how the entire community influences ecological processes. The main objective of this thesis is to develop and to test concepts for a trait-driven quantification of ecosystem services through the assessment of the effects of land management on soil processes. In particular, it focuses on exploring the potential of a trait-based approach in identifying and better understanding the response of the soil biota to environmental pressures and analyses the responses of soil organisms in terms of changes in functional trait distribution and trophic interactions. This work shows that approaches taking the whole soil community into consideration are more suitable to give insight into the effect of anthropogenic pressure on ecosystem functioning than approaches based on single taxonomic groups. Moreover, performing combined analysis (e.g. analysing body-mass distribution and trophic grouping) helps to better identify community response to environmental pressure. A clear methodology for the next step, i.e. quantification of ecosystem services, is still lacking due to the current difficulties to link and quantify the effect of anthropogenic pressure to ecosystem functioning in soil. For this reason, it is essential that methods analysed in this thesis will be further explored under different environmental pressures to enable the development of tools to be used at the interface of science and society for sustainable development.