Soil organic matter in arid and semiarid ecosystems: Sources, accumulation, and distribution

Abstract

Abstract Accumulation of organic carbon and formation of humus in arid and semi‐arid soils are reviewed with special attention to sources and distribution of organic matter, factors affecting humus formation and accumulation, transfer of organic debris to soil organic matter, and organic matter management. The character of vegetation is a major factor determining rate of organic decomposition and the quality, quantity, and distribution of soil organic matter, but the influence of other soil‐forming factors is sufficient to complicate the pattern and process of humus formation. Over a broad scale moisture and temperature are especially important. Patterns of soil organic matter distribution and litter decomposition are characteristic for arid and semiarid environments; they vary with the state of the system but involve complex interrelations. Trends in soil humus research and approaches needed to answer crucial ecological questions are reviewed.