In order to monitor trends in global changes and predict their impacts on ecosystems, scientists and policymakers are in a constant search for integrative, cost-effective indicators of ecological change. Functional traits have emerged as practical tools to track environmental changes (response traits) and assess their effects on ecosystem processes (effect traits). Despite the impressive advances in functional diversity research, traits of organisms other than plants; such as soil lichens and mosses (biocrusts), are still largely unexplored. Nevertheless, biocrust traits such as stable isotope ratios, nutrient content and pH are easy to measure, highly sensitive to environmental conditions and integrative; as a set of indicators, they can reflect changes in climate and nutrient sources and availability. Also, due to their response-effect nature, biocrust tissue traits have an anticipatory character; shifts in their values will, in turn, affect other ecosystem processes (e.g. decomposition rates) and components (e.g. plant and microbial communities). To date, biocrusts stable isotope ratios, nutrient content and pH have been reported for a limited set of species in a systematic way and experimental studies are still scarce in the literature.
The overall objective of INDECRUST is to assess the suitability of biocrusts tissue traits as ecological indicators of global changes and their impacts on ecosystem properties and functioning. This project adopted a multi-scale, hierarchical approach to address the following questions: 1) how variable are tissue traits (i.e. isotope ratios, nutrient content and pH) between lichens and mosses, and among and within species at the local scale? Is soil composition driving trait variability? 2) Are tissue traits good predictors of biocrust and plant dynamics in the future (e.g. decomposition rates, soil fertility)? In other words, can they anticipate global change impacts and feed-backs in the long-term? 3) Do tissue traits respond to changes in climate and atmospheric composition and, simultaneously, indicate changes in other ecosystem components (i.e. soil microbial communities) and soil functioning?
The results of this project reveal the existence of a high interspecific variability in dryland biocrust tissue traits, their sensitivity to environmental changes and their effects on soil fertility and functioning. These results confirm the idea that biocrust tissue traits are integrative, cost-effective indicators of global change drivers, on the one hand, and good predictors of biocrust effects on soil fertility and functioning, on the other. Overall, these findings allow us to evidence changes in environmental conditions and to better predict how global change drivers will impact dryland systems. The knowledge generated in this project will help to improve monitoring programs, biodiversity conservation actions and environmental policy strategies.
