不同土地利用类型对伊犁地区土壤活性有机碳库和碳库管理指数的影响

土壤碳库管理指数（CPMI）可以比较准确地发现人为因素对土地利用的干扰情况。以伊犁河谷不同土地利用类型（耕地、林地、草地和荒地）为研究对象，分析了不同土地利用类型土壤有机碳（SOC）含量、活性有机碳含量及其在SOC中的分配情况，各类有机碳含量之间的相关性、CPMI。研究表明:（1）不同土地利用类型SOC含量和水溶性有机碳（WSOC）含量有显著差异，SOC含量为草地 > 林地 > 耕地 > 荒地；WSOC含量为耕地（最高） > 荒地（最低）；易氧化碳（ROC）含量为草地最低；在0—20 cm和20—40 cm土层，微生物量碳（MBC）含量为草地（最高） > 林地（最低）；ROC含量为荒地高于草地。不同土地利用类型SOC含量均随土层深度增加而降低；ROC含量均随土层深度增加而升高；除林地外，其他样地MBC含量均随土层深度增加呈先升高后降低趋势，而WSOC含量均随土层深度增加而逐渐降低。（2）不同土地利用类型下ROC，MBC和WSOC所占SOC比例各不相同，且碳库的活度主要取决于ROC所占比例，ROC所占比例为荒地 > 耕地 > 林地 > 草地；MBC所占比例为荒地 > 耕地 > 草地 > 林地；WSOC所占比例为耕地 > 林地 > 荒地 > 草地。同一土地利用类型各活性有机碳所占比例情况为ROC > MBC > WSOC。（3）不考虑土层深度影响，耕地ROC含量与MBC含量呈极显著线性负相关；林地SOC含量与ROC含量呈显著线性负相关；荒地SOC含量与WSOC含量呈极显著线性正相关。不同土地利用类型下SOC，ROC，MBC，WSOC含量之间线性相关程度总体偏低。（4）同一土地利用类型，CPMI均随土层深度的加深先增大后减小；0—20 cm土层的CPMI为林地 > 荒地（100） > 耕地 > 草地。土地利用类型由荒地、草地、耕地转变为林地，有利于CPMI的提高，有利于土壤培肥，促进碳循环。

Effects of Different Land Use Patterns on Soil Active Organic Carbon Pool and Carbon Pool Management Index in Yili Area,Xinjiang Uygur Autonomous Region

The soil carbon pool management index (CPMI) can be used to find out the interference of human factors on land use patterns. The different land use patterns (cultivated land, forest land, grassland and wasteland) in Yili River Valley were selected as the study examples. Soil organic carbon (SOC) content, active organic carbon content and the ratio of SOC content in the different land use patterns, and correlation between various patterns of organic carbon content, CPMI were analyzed. The results showed that: (1) there were significant differences in SOC contents and WSOC (water soluble organic carbon) contents in different land use patterns, SOC content decreased in the order: grassland>forest land>cultivated land>wasteland; WSOC content decreased in the sequence: cultivated land (highest) >wasteland (minimum); the lowest ROC (readily oxidized organic carbon) content is grassland; MBC (microbial biomass carbon) content in the soil layers in 0—20 cm and 20—40 cm decreased in the order: grassland (highest) >forest land (minimum); ROC content of wasteland is higher than grassland. The contents of SOC in different land use patterns decreased with the increase of soil depth; the content of ROC increased with the increase of soil depth; in addition to forest land, MBC contents of the other samples increased with soil depth increase first and then decreased, but WSOC content decreased with the increase of the soil depth; (2) under different land use patterns, the proportion of ROC, MBC and WSOC in SOC were not identical and the activity of carbon pool mainly depended on the proportion of ROC, the proportion of ROC decreased in the order: wasteland > cultivated land > forest land > grassland; the proportion of MBC decreased in the order: wasteland > cultivated land > grassland > forest land; the proportion of WSOC decreased in the sequence: cultivated land > forest land > wasteland > grassland. The proportion of active organic carbon in the same land use decreased in the order: ROC > MBC > WSOC; (3) without considering the influence of soil layer, the content of ROC in cultivated land was negatively correlated with the content of MBC; the content of SOC in forest was significantly negatively correlated with ROC content; the content of SOC in the wasteland was significantly positively correlated with the WSOC content, the linear correlation between SOC, ROC, MBC and WSOC content in different land use patterns was generally poor; (4) in the same land use patterns, CPMI with the depth of the soil layer increased first and then decreased; the CPMI of the 0—20 cm soil layer decreased in the order: forest land > wasteland (100) > cultivated land > grassland. Land use pattern conversion of wasteland, grassland, cultivated land to forestland is useful to the improvement of CPMI, it is advantageous to soil fertility, promoting carbon cycle.