喀斯特峰丛洼地土地利用演变及其土壤侵蚀效应

Land use change and its effects on soil erosion in karst cluster-peak depression region.

人类不合理活动所导致的土地利用演变是引发土壤侵蚀及其负面生态效应的主要机制,因此研究二者的耦合关系具有重要意义。本文以贵州普定县的石人寨峰丛洼地为主要研究区域,从景观生态学的"格局-过程-尺度"、"源、汇景观"原理及其景观空间负荷对比指数(LCI)出发,应用稳定同位素和放射性核素示踪方法,揭示土地利用演变及其土壤侵蚀特征,并进一步分析二者的耦合关系。结果表明,该洼地在土壤剖面约100cm处记录到坡地森林遭受砍伐后变为耕地的事件,随后从坡地侵蚀下来的大量土壤沉积于洼地底部;该事件之后进入垦殖期,在洼地中轮种玉米、油菜、大豆等农作物。本研究为优化当地土地利用结构,改善流域的水土流失状况提供了新的视角。

The land use change induced by unreasonable human activities may result in soil erosion and other negative ecological effects,and thus,to understand their coupling relations is of great significance.Taking a representative karst cluster-peak depression region of Shirenzhai in Puding of Guizhou,Southwest China as study area,and by using stable and radioactive isotopes tracing,this paper studied the land use change and its effects on soil erosion since the 1960s,and analyzed the coupling relationships between them,based on the ＂pattern-process-scale＂ and the ＂source and sink landscape＂ theories of landscape ecology and the location-weighted landscape contrast index（LCI）.In the study area,an event of sloping field forest transformed into cultivated land was recorded at about 100 cm depth in soil profile,and subsequently,a large amount of eroded soil from the sloping field was precipitated on the depression.After the event,cultivation period came.The depression was cultivated with corn,rape,and soybean in rotation.This study provided a new perspective for optimizing the local land use structure and controlling the water and soil erosion in watershed.