高原鼠兔洞口区侵蚀过程高山草甸土壤的变化

Changes of Soil Physical and Chemical Property of Alpine Kobresia Meadow Around the Plateau Pika Entrances in the Process of Erosion

在西藏那曲高山嵩草草甸,选择高原鼠兔活动区域不同高度土堆和不同深度侵蚀坑,分析表层土壤粒度和养分。结果表明,高原鼠兔掘洞形成洞口土堆,造成草甸土壤发生侵蚀,侵蚀程度随着侵蚀坑深度逐渐增加而减弱,在侵蚀坑深度达到20cm时侵蚀基本停止;在侵蚀过程中,细粒物质减少,砾石含量增加。在强烈侵蚀阶段初期,有机物分解条件改善,土堆表层土壤的有机质、全N、全P、水解N、速效K含量提高,但土壤养分物质在侵蚀作用下迅速流失,土壤有机质、全N、全P、水解N、速效P和速效K含量减少;在侵蚀减缓阶段,养分损失速度减缓,补偿作用逐渐增加;在侵蚀基本停止阶段,土壤表层有机质、全N、水解N和速效K含量明显增加。

Based on the different mound height or the depth of erosion pits,the impacts of mounds Produced by the plateau pika(Ochotona curzoniae) on the soil grain size,organic matter,total nitrogen,phosphorus,potassium,hydrolyzable nitrogen were evaluted.The results showed that the erosion occurred as soon as the mounds produced by the plateau pika,the erosion declined with the increased of depth of pit,and erosion ceased when the pit depth eventually stabilized at around 20 cm.The rates of silt and clay decreased but that of gravel and sand increased in process of erosion;at the beginning of the period of serious erosion,the contents of organic matter,total N,total P,hydrolyzable N,and potassium oxide in surface soil increased due to the improvement of decomposition condition.But,due to the extension of erosion,the contents of organic matter,total N,total P,hydrolyzable N,rapid available phosphorus,and potassium oxide decreased rapidly in process of soil erosion.At the period of erosion palliation,benefit from intercept of pit and improved coverage of vegetation,soil nutrition had got compensated and this prevents the soil nutrition from losting more.The contents of organic matter,total N,hydrolyzable N,and potassium oxide increased rapidly after the erosion ceased.