MOdeling of carbon and nitrogen cycling in arid and semiarid ecosystems

In this Chapter we present a general discussion of the dynamics of soil nutrient cycles with special attentions to the interaction with hydrological processes in semi-arid systems, and with emphasis on modeling issues. We will present an analytical approach developed by the authors and co-workers to model the propagation of hydrologic fluctuation through the various components of the soil biogeochemical cycles of arid and semiarid ecosystems. We do not attempt to provide here a complete review of the subject (see Chapters 12-14. and 18 for related discussion on soil nutrient cycles in drylands) but rather focus on interaction between hydrological and ecological processes and outline some open problems and future directions for research.