重庆岩溶区土壤有机碳库的估算及其空间分布特征

基于重庆市第二次土壤普查和2007年测土配方施肥的1 412个土壤剖面数据,结合重庆岩溶区土壤图、土地利用现状图和行政区划图,在地理信息系统技术的支持下,对重庆岩溶区土壤有机碳密度及储量进行了估算,同时引入有机碳丰度指数这一指标,对有机碳在不同土壤和不同景观中的分布特征进行了分析.结果表明:重庆岩溶区20 cm和100 cm深度的土壤有机碳储量分别为1.43×1011 kg和3.29×1011 kg.不同土地利用方式下重庆岩溶区土壤有机碳密度分布不均匀,20 cm深度的土壤有机碳密度介于1.26～7.20 kg m-2之间,100 cm深度的土壤有机碳密度介于1.43～25.72 kg m-2之间.重庆岩溶区土壤有机碳库在不同土壤和不同景观中的分布具有高度的空间变异性,20 cm深度的土壤和景观有机碳丰度指数分别在0.73～1.74和0.39～1.20之间,100 cm深度的土壤和景观有机碳丰度指数分别在0.32～3.00和0.46～1.70之间.与全国的平均水平相比,单位面积上20 cm深度土壤有机碳储量重庆岩溶区高于全国的平均水平,但单位面积上100 cm深度土壤有机碳储量重庆岩溶区低于全国的平均水平,总体而言,重庆岩溶区是土壤有机碳储量相对贫乏的区域.

Estimation of soil organic carbon storage and the characteristic of carbon spatial distributions in karst area, Chongqing, China

The estimation of soil organic carbon storage is very important to the research of carbon cycle. The soil organic carbon density and storage of Chongqing karst area was estimated, using the data of 1412 soil profile from the second soil survey of China and formulating fertilization for soil conditions in 2007. Integrating the soil map, land use status quo map and district map of Chongqing karst area, the index of soil organic abundance were introduced and the characteristic of soil organic distribution in different soil and landscapes were analyzed. Results showed: the storage of soil organic carbon of Chongqing karst area to the depths of 20 cm and 100 cm were 1.43×1011 kg and 3.29×1011 kg, respectively. Carbon density of 20 cm soil was 1.26-7.20 kg m-2, and carbon density of 100 cm soil was 1.43-25.72 kg m-2. The amount of soil organic carbon varied significantly at different soils and landscapes, the index of soil organic abundance of soils and landscapes at 20 cm depth ranged from 0.73-1.74 and 0.39-1.20, and that at 100 cm depth changed between 0.32-3.00 and 0.46-1.70, respectively. The soil organic carbon storage of unit area at 20 cm depth was above the average level of China, but that at 100 cm depth was below the average level of China in Chongqing karst area. In a word, the soil organic carbon storage was relatively indigent in Chongqing karst area.