C, N, and P Nutrient Cycling in Drylands. (Microbiology of Hot Deserts First Edition)

Abstract

Drylands play a significant role in the global biogeochemical cycling of nutrients (carbon, nitrogen, and phosphorus) through abiotic (geological, atmospheric, and hydrological) and biotic (animals, insects, plants, and microorganisms) pathways. They act as important carbon reservoirs and are estimated to store over 30% of the global soil organic carbon reserve. However, nitrogen and phosphorus availability are major limiting factors for biological activity in these oligotrophic environments, affecting community structure, species diversity, and other ecosystem functions (e.g., nutrient cycling and productivity). Nutrient cycling in desert soils is primarily achieved by plant and microbial communities, in particular soil microbial communities, biological soil crusts, hypoliths, and endoliths. Drylands are highly sensitive and prone to disturbance and land degradation resulting from desertification. Changes induced by climate (e.g., precipitation and temperature), structural and temporal variability (nutrient accumulation and distribution of minerals, seasonal variation, and differences in turnover rates), and human activity often alter nutrient cycles that negatively affect the structure and function of these ecosystems (e.g., decreasing carbon storage capacity, increasing NOx emissions, and reducing phosphorus cycling). Comprehending the extent, nature, magnitude, and reversibility of such changes is urgent, given the global importance of drylands in terms of carbon sequestration, greenhouse gas emissions, ecology and biodiversity, and human habitation.