北京山区典型森林土壤的养分空间变异与环境因子的关系

根据北京山区典型森林植被的分布设置采样点,应用典范对应分析(CCA)法,对土壤养分空间变异与环境因子的关系进行分析.结果显示:研究区土壤有机质、氮、钾含量相对丰富,严重缺磷,养分整体表现为中等变异.从CCA排序结果看,环境对养分变异的影响程度及因子数量均随土层深度的增加而减小.0—10cm、10—20cm土层养分的影响因子相似,主要为坡位、海拔、0—20cm土层含水量及容重;20—40cm土层养分的主要影响因子为坡位、海拔、0—40cm土层含水量及容重;40—60cm土层养分的主要影响因子为该土层的pH值.对不同养分指标而言,有机质、全氮和碱解氮的主要影响因子为坡位、土壤含水量、海拔及林分类型;速效钾主要受土壤厚度影响;其它指标受环境因子的影响小.环境因子的定量分离结果显示,其在总体上解释了83.33%的养分变异,其中土壤相关因子解释了50.37%,地形因子解释了7.96%,二者的耦合作用解释了25%.

The Relationship between Environmental Factors and Spatial Variability of Soil Nutrients for Typical Forest Types in Beijing Mountainous Area

In order to explore the influence of environmental factors on the variability of soil nutrients in Beijing mountainous forests,locations were set for soil sampling based on the distribution of typical forest types and the canonical correspondence analysis(CCA)was used.The results indicated that the soil nutrients had modestly spatial variability with relatively abundant soil organic matter,nitrogen and potassium but seriously deficient phosphorus.According to CCA,both the extent and number of environmental factors with influence on soil nutrients decreased with the increasing of soil depth.Specifically,for soil horizons of 0—10cm and 10—20cm,soil nutrients were mainly affected by slope position,elevation,0—20cm soil water content and bulk density;for 20—40cm soil horizon,soil nutrients were mainly affected by slop position,elevation,0—40cm soil water content and bulk density;while for 40—60cm soil horizon,soil nutrients were mainly affected by 40—60cm pH value.On the other hand,the environmental factors with influence also varied for different nutrient categories.Specifically,organic matter,total nitrogen and effective nitrogen were mainly affected by slope of position,elevation,soil water content and forest types;available potassium was mainly affected by thickness of soil;while other nutrient categories were insignificantly affected by environmental factors.Quantitative analysis of the relationship between soil nutrients and environmental factors showed that all environmental factors could explain 83.33% of spatial variability in soil nutrients,50.37% of which was explained by soil related factors,7.96% by topographic factors,and 25% by interactive factors between topography and soil.