异龙湖湖滨带不同环境梯度下土壤养分空间变异性

随着环境梯度的变化，生态系统的特征会发生明显的变异，土壤是其重要的表征要素。以纵向岭谷区红河流域异龙湖湖滨带为案例，运用多种统计分析方法对其不同环境梯度下土壤单个养分指标和土壤养分综合质量的空间分布特征进行了研究，结果表明：在北部湖滨坡地，海拔对土壤养分空间分布的影响并不十分显著，而坡位对其影响较大；北部湖滨农田土壤，水分梯度对钾的影响较大，全氮和有机质则一部分受水分梯度影响，另一部分受径流作用的影响；异龙湖湖滨带土壤养分综合质量指数大小的排序为：南部湖演农田〉北部湖滨农田〉北部湖滨坡地）南部湖滨坡地。还探讨了不同环境因子对单个土壤养分指标和土壤养分综合质量的影响，其中，气温、湿度、坡向和坡型对土壤中磷空间分布的影响较大，土壤含水量、坡度和海拔对土壤有机质、全氮和全钾的影响较大；土壤含水量即水分梯度对土壤养分综合质量影响最大。

Spatial variability and distribution of soil nutrient contents along different environmental gradients of Yilong lake shore

The characteristic of ecosystem changes along the environmental gradients and the soil is one of its important indicators. We studied the spatial variation and distribution of soil nutrient contents in Yilong lake area, located in the Longitudinal Range-Gorge Region with rich biodiversity and being one of the largest Platue Lakes of YunNan Province, China. Soil samples were taken from four areas along the different environmental gradients, concluding Northern Farm (NF), Northern Hill (NH), Southern Farm (SF) and Southern Hill (SH). The organic matter, total N, P, and K(TN,TP,TK), and available N, P, and K(AN,AP,AK) in the soil samples were measured. The soil quality index was calculated by principle component analysis, using the measured soil nutrient contents. Correlation matrix was created among various soil nutrient contents and altitude or soil moisture content for NH or NF, respectively. Average contents of soil nutrients were calculated in the studied four areas. Principle component analysis showed that the critical factor affecting the space distribution of the NH soil nutrients was not the altitude but the slope. The contents of most nutrients were lowest at the foot and the peak of the NH and were highest at the middle of it except the potassium. The soil of NH was rich in organic matter and total nitrogen. In NF, however, the soil nutrient contents gradually decreased with the decrease of soil moisture except the organic matter and total nitrogen, probably because some of organic matter and total nitrogen was moved by precipitation from the hill soil with high content of them to the farm near the road. The soil moisture played an important role to determine the soil nutrient contents distribution. The soil of NF was rich in potassium and phosphorus while the NH soils contained high contents of the organic matter and nitrogen. The soil of Yilong lake shore generally contained low content of phosphors but high content of potassium. The soil quality of the four studied areas was in the order: SF>NF>NH>SH, indicated by the integrated soil quality index. This study also investigated the relationship between the single soil nutrient factors and soil quality index and the environmental factors. The environmental factors included air humidity, soil moisture, slope, altitude, air temperature, slope shape, and orientation. The results showed that the air temperature, air humidity, orientation, and the slope shape played an important role to the phosphorus spatial distribution. On the other hand, the soil moisture, slope, and the altitude played an important role to the spatial distribution of the organic matter, total nitrogen and Potassium. In addition, the soil moisture was the critical factor affecting the soil quality. The regression equation between soil nutrient primary components and soil quality was: soil quality=1.842 0.465 N_-PC1 0.214 N_-PC_-2 (N_-PC was the primary component of the soil nutrient factors).