三江源地区不同退化程度高寒草原植被与土壤特征分析

Analysis on vegetation and soil characteristics of alpine grassland with different degradation degrees in Three Rivers Region

摘要:

【目的】探究三江源不同退化程度高寒草原土壤理化性质与植被之间的关系。【方法】以青海省玛多县不同退化程度高寒草原为研究对象，测定不同退化程度植被群落特征及各土层(0~10、10~ 20、20~30 cm 土层)土壤理化性质(土壤全氮、速效氮、全磷、速效磷、全钾、速效钾、有机质含量、pH 值以及容重)，分析影响高寒草地植被群落退化的关键土壤环境因素。【结果】1)随着高寒草原退化的加剧，土壤有机质、全氮、全钾、速效氮、速效磷、速效钾含量均显著降低，土壤容重显著增大；2)草地多样性指数、丰富度、地上生物量逐渐降低；3)草地多样性指数、丰富度、地上生物量与土壤全氮、全钾、速效氮、速效磷、有机质含量呈正相关；4)土壤速效氮与速效磷是影响退化高寒草原植被特征变化的主要因素。【结论】不同退化程度土壤中的速效养分含量较低，成为阻碍牧草生长的限制因子，其中主要受到磷的限制，氮次之。

Abstract:

【Objective】 In order to explore the relationship between the soil physical and chemical properties and vegetation in alpine grasslands with different degradation degrees in the Three Rivers Region.【Method】 The alpine grassland with different degradation degrees in Maduo County of Qinghai Province was taken as the research object. The characteristics of vegetation community with different degradation degrees and the soil physical and chemical properties (soil total nitrogen，available nitrogen，total phosphorus，available phosphorus，total potassium，available potassium，organic matter，pH and bulk density ) of each soil layer (0~10，10~0，20~30 cm ) were measured. The key soil environmental factors affecting the degradation of vegetation community in alpine grassland were analyzed. 【Result】1) With the aggravation of alpine grassland degradation，the contents of soil organic matter，total nitrogen， total potassium，available nitrogen，available phosphorus and available potassium decreased significantly，and soil bulk density increased significantly；2) Grassland diversity index，richness and aboveground biomass decreased gradually； 3) Grassland diversity index，richness and aboveground biomass were positively correlated with soil total nitrogen，to‐ tal potassium，available nitrogen，available phosphorus and organic matter；4) RDA analysis showed that soil avail‐ able nitrogen and available phosphorus were the main factors affecting the vegetation characteristics of degraded al‐ pine grassland.【Conclusion】 The available nutrients in degraded soil in alpine grassland area were low，which be‐ came a limiting factor to hinder the growth of forage. the degradation of alpine grassland was mainly restricted by strong phosphorus，following by nitrogen.