The Carbon Cycle in Drylands

摘要: Drylands are characterized by an aridity index (ratio of annual rainfall to potential evapotranspiration) lower than 0.65, and occupy nearly a third the total land surface. Globally, organic inorganic carbon (C) storage in such water-limited systems is about 20–30% terrestrial global total. The soil C (SOC) stored drylands approximately 230 Pg. content dryland biomass four times that as SOC (65 Pg). (SIC) pools estimated be more twice for may exceed factor 10 some arid lands. These statistics can modified significantly taking into account anthropogenic practices. Ideally, NT management potentially increase 20%, while non-grazing grassland could 45%. ecosystems highly vulnerable climatic changes susceptible desertification, leading reduction pool. In addition, due conditions large percentage bare soil, other processes besides photosynthesis respiration contribute sequestration or gaseous emissions atmosphere. include geochemical processes, formation secondary carbonates, bio-sequestration, subsoil ventilation, erosion photodegradation even dominate ecosystem exchange during dry season. Such contributions limit use biological models provide estimates pool drylands. And differences measured net with atmosphere, ranging from −106 145 g m−2 deserts −190 140 grasslands not easily explained. A better understanding cycle relevant Kyoto Protocol order prevent degradation This survey reviews sink capacities drylands, together analysis principal involved and, finally, summarizes suggestions practices capability reduce losses