SOIL CARBON STOCK PATTERNS OF DIFFERENT LAND USE TYPES IN THE LOWER LHASA RIVER VALLEY, TIBET PLATEAU

The vertical distribution of soil organic carbon and the effect of land use change on soil organic carbon storage are studied at Dagze farm in the lower reaches of Lhasa River Valley, Tibetan Plateau. Generally, soil organic matter in the valley is low. However, soil organic matters in swamp meadow and poplar forest are relatively higher than those of other soil types. Soil organic carbon accumulated relatively in lower soil layer in swamp meadow, poplar forest and scrub-steppe, while soil organic carbon distributed evenly in arable soils such as farmland, wasteland and plant nursery. The carbon density and carbon storage increased while conversion from farmland to abandoned wasteland, plant nursery and poplar forest, of which there was a greater carbon sequestration in poplar forest conversed from farmland. The Dagze farm had a soil pool of 1.071×104 Mg organic carbon in land area of 283.039 hm2, of which meadow soil and scrub-steppe soil accounted for 77.6% organic carbon in 51.9% of land area.