天山北坡绿洲土壤有机碳和养分时空变异特征

本文以天山北坡三工河流域绿洲作为研究区,利用1982、1999和2003年土壤养分数据,应用地统计学方法,分析绿洲土壤有机碳和养分的时空变异特征。结果显示:研究区1982、1999和2003年土壤有机碳和养分具有显著的差异性。空间结构上,土壤有机碳和养分具有中等或较弱的空间自相关;受土壤类型、种植作物种类等的影响,研究区土壤有机碳具有较强的各向异性,但碱解氮、速效磷和速效钾各向异性较弱。Kriging和IDW插值分析表明,土壤有机碳和养分总体呈增加的趋势,绿洲土壤表现为“碳汇”,尤其在种植6年以上的多年生作物分布区,土壤“碳汇”趋势更加明显,说明以绿洲农业为主的人类活动基本合理,土壤质量正逐步改善。

Spatio-temporal variability of soil organic C and nutrients in the oasis of the northern slope of the Tianshan Mountains

The relationship between soil organic C and land use change is one of the important fields in the study on global change.In the past 20 years,with the rapid economic development and population increase in China,large-scale land reclamation resulted in oasis expansion and natural desert vegetation decrease,especially in Xinjiang.Taking the oasis of Sangong river watershed as a study case,we have evaluated the spatio-temporal variability of soil organic C and nutrients.The results show that:(1) The soil OC contents was roughly equivalent in 1982 and 2003,but lower in 1999 than in 1982 and 2003.The AN,AP and AK contents tended to increase with cultivation time.(2) The nugget-to-sill ratio of soil OC changed from 53.3% to 70.3%,suggesting that the spatial correlation belongs to moderate class.However,the nugget-to-sill of AN,AP and AK is higher,suggesting that the spatial correlation belongs to low class.Influenced by soil types and planting crops of the study area,the anisotropies of soil OC were obvious,while those of AN,AP and AK were weaker.(3) The results estimated by Kriging and IDW showed that soil OC declined from 1982 to 1999,and then increased from 1999 to 2003.AN,AP and AK increased significantly from 1982 to 1999,while decreased from 1999 to 2003 due to balanced fertilization application.In conclusion,soil OC had been increasing with the cultivation time in the Sangong river watershed,indicating that oasis soil presented C sink.This also indicates that the human activities in the oasis were reasonable and the environment of the oasis was improved.