伊犁山地不同海拔土壤有机碳的分布

以乌孙山北坡、科古琴山南坡为例,分析伊犁山地南北坡土壤有机碳的分布特征和影响因素。结果表明:①0-50 cm范围内,高寒草甸、草甸草原土壤有机碳含量较高,荒漠草原土壤有机碳含量最低。土壤有机碳含量均随土壤深度的增加而降低,高寒草甸随土壤深度的增加土壤有机碳下降幅度最大;②伊犁山地土壤腐殖化程度高,氮矿化能力强。大部分海拔的土壤碳氮比随土壤深度的增加而减少。河谷南坡碳氮比降低速率要大于河谷北坡。③土壤有机碳与全氮、全磷以及土壤含水率表现出良好的正相关性;与pH值表现出较好的负相关性,特别是20-50 cm处。植被类型分布和人类活动影响对土壤有机碳垂直变化影响显著。

Soil Organic Carbon Changing With Altitudes on the Ili Mountainous Region

Based on data from field investigations and laboratory analysis in 2008 and 2009,soil organic carbon distribution and its influencing factors were studied,taking the northern slope of Wusun Mountain and the southern slope of Keguqin Mountain on the Ili mountainous region,Xinjiang as the study area.The results showed that: 1) Soil organic carbon content in 0-50cm soil layer of alpine meadow and meadow steppe was higher and that was lower in desert steppe.Soil organic carbon content decreased with the increasing of soil depth,both changing range and rate of soil organic carbon content was constant in 0-10cm and 10-20cm soil layer of the Ili mountainous region,however the soil organic carbon content was showed decreasing trend with high changing range in alpine meadow which is on over 2700m above the sea level,and that was slower in Temperate meadow steppe.The desert steppe had the slowest changing range.The difference in decreasing range of soil organic carbon has proved that its vertical distribution pattern was also different;2) the soil carbon/nitrogen ratio of southern and northern slope of Ili mountainous region was between7-15 and the soil had higher humification degree and nitrogen mineralization potential.Soil carbon/nitrogen ratio in most sites in different elevation decreased with the increasing of soil depth,and the southern slope of Ili mountainous region had the higher soil carbon/nitrogen decreasing ratio than that of the northern slope;3) soil organic carbon had a positive significant correlation with soil total nitrogen,total phosphorus and soil moisture(P<0.01),and had a negative significant correlation with pH value,especially in 20-50cm soil layer.The distribution of vegetation types and human activities significantly affected the vertical distribution of soil organic carbon.Although the intensively grazing of alpine meadow had caused serious lost of soil organic carbon in this area,but due to the rich organic carbon content in 0-10cm soil layer,its vertical distribution pattern was still obvious.Therefore,the protection of the surface soil layer would play a significant role in maintaining the stability of soil carbon sink in this area.