Abstract:

In order to understand the effect of different plant communities on soil organic carbon content， 4 plant communities were selected in the middle of the northern slope of Tianshan mountains， including Picea schrenkiana， Iris loczyi shrub， Achnatherum inebrians and Malva rotundifoli. 5 samples of 1 m × 1 m were set in each community， and the soil samples were taken by 5-point for analyzing the content and constituent of total organic carbon in 0—10， 10—20， 20—30， 30—40 and 40—50 cm soil layers. The results showed that the soil organic carbon contents in 0—20 cm layer of 4 plant communities were higher， and decreased to be stable in 30—50 cm soil layers. The total soil organic carbon content of Picea schrenkiana was 244.24 g·kg^-1， which was significantly higher than other communities with 86.62%， 20.66% and 41.32% increase to Iris loczyi shrub， Achnatherum inebrians and Malva rotundifoli， respectively. The organic carbon contents of 3 different oxidation degrees in 4 plant communities showed highly oxidizable organic carbon > difficult to oxidize organic carbon > easily oxidizable organic carbon. In 0—10 and 10—20 cm soil layers， the contents of highly oxidizable and the oxidizable organic carbon were higher in Achnatherum inebrians community. For the content of difficult to oxidize organic carbon， Malva rotundifoli community was higher in soil of 30—50 cm layer， Picea schrenkiana community was higher in soil of 10—20， 40—50 cm layers， Achnatherum inebrians community was higher in soil of 20—30， 30—40 cm layers. The contents of inert organic carbon in 4 communities were 48.61， 29.46， 54.46 and 39.17 g·kg^-1， respectively， accounting for about 20% of the total organic carbon. It indicated that different plant community in the northern slope of Tianshan mountains would affect the contents， composition and spatial distribution of soil organic carbon. As a sensitive indicator of soil carbon content dynamic change， soil organic carbon could timely reflect the turnover and dynamic change process of soil organic carbon pool.

Key words: soil organic carbon, different plant communities, highly oxidized organic carbon, easily oxidized organic carbon, difficult to oxidize organic carbon, inert organic carbon

摘要：

为明确植物群落对土壤有机碳的影响，在天山北坡中段选择雪岭云杉（Picea schrenkiana）、鸢尾（Iris loczyi）灌丛、醉马草（Achnatherum inebrians）和圆叶锦葵（Malva rotundifoli）4个植物群落，在每个群落设置5个1 m×1 m的样方，采取5点取样分析不同土层（0—10、10—20、20—30、30—40和40—50 cm）土壤有机碳及其组分含量。结果表明，4个典型植物群落土壤均表现为0—20 cm土壤有机碳含量较高，在30—50 cm土壤不同组分有机碳含量逐渐下降且趋于稳定；雪岭云杉植物群落土壤有机碳含量（244.24 g·kg^-1）显著高于其他植物群落，较醉马草植物群落、鸢尾灌丛植物群落和锦葵植物群落分别提高86.62%、20.66%和41.32%。4个植物群落下，3种不同氧化程度的有机碳含量均表现为极易氧化有机碳>难氧化有机碳>易氧化有机碳。0—10和10—20 cm土层，极易氧化和易氧化土壤有机碳含量均为雪岭云杉植物群落最高。对于难氧化土壤有机碳，锦葵植物群落在0—10 cm最高，雪岭云杉林下植物群落在10—20、40—50 cm最高，醉马草植物群落在20—30、30—40 cm最高。各群落惰性有机碳含量分别为48.61、29.46、54.46和39.17 g·kg^-1，占总有机碳20％左右。天山北坡不同植物群落会影响土壤有机碳含量及其组成和空间分布，土壤有机碳可作为土壤含碳量动态变化的敏感性指标，及时反映土壤有机碳库的周转和动态变化过程。

关键词: 土壤有机碳, 不同植物群落, 极易氧化有机碳, 易氧化有机碳, 难氧化有机碳, 惰性有机碳