"The aim of this project is to investigate the role of biological soil crusts (BSC) in the C balance in arid and semiarid zones in function of their successional stages and environmental factors. To achieve this goal, BIOSOC will monitor the CO2 fluxes along with key meteorological parameters controlling the CO2 exchange rates from representative biological soil crusts at their different successional stages and will map their spatial extent using novel techniques adapted for covering large areas. Finally, the quantification of the temporal and spatial variability in CO2 exchange will result in a preliminary assessment of the BSC contribution to the greenhouse gas balance at catchment scale. The results of this project will improve knowledge of the C balance in Mediterranean ecosystems and the important role that BSCs may have as C sinks. Such results will show the vulnerability of crusted soils to future climate changes and ultimately the management practices necessary to preserve these ecosystems. The results of this work will also be the basis for future development of a tool for regional classification of stages of development of BSCs which may be used as a soil degradation indicator, as well as generate a model that can be used for the C balance in crusted soils in larger Mediterranean areas. Such information could be useful for filling in gaps in national (CARBORAR), continental (GHG-Europe) and worldwide (FLUXNET) databases on carbon exchange in BSC ecosystems. BIOSOC is also complementary to work on the use of hyperspectral techniques to detect soil organic carbon in-situ that has been started within the DIGISOIL project (EU FP 7)."