云南乌蒙山区土壤养分空间变异及海拔梯度分布规律

Spatial Variability and Altitudinal Gradient Distribution Pattern of Soil Nutrients in Wumeng Mountainous Region, Yunnan

为探知云南乌蒙山区土壤养分空间分布格局和规律,应用经典统计学和地统计学方法对云南乌蒙山区土壤的酸碱性(pH值)、有机质(SOM)、全氮(TN)、有效磷(AP)、速效钾(AK)含量,进行空间变异分析和海拔梯度分布规律研究。结果表明:云南乌蒙山区土壤整体呈酸性,绝大部分地区的SOM、TN、AP、AK处于中等或较高水平,各土壤养分呈现中等以上变异性。空间变异分析显示5种养分的最佳拟合模型均为指数模型,pH值、TN空间自相关强烈,空间变异主要受结构性因素影响,SOM、AP、AK具有中度空间自相关,受结构性因素和随机性因素共同影响,土壤pH值和各养分含量空间分布均呈斑块状,条带性分布趋势不明显;云南乌蒙山区pH值与海拔整体呈极显著负相关,各养分含量与海拔极显著正相关,但北部、中部、南部相互存在差异,海拔是影响乌蒙山区土壤pH值和养分含量空间异质性的重要结构性因素,但土壤SOM、AP、AK还受随机因素干扰。本研究有助于进一步从区域尺度上探索山地土壤养分空间异质性的形成机理。

To explore the spatial heterogeneity and the distribution pattern of soil nutrients in Wumeng mountainous region, Yunnan, the spatial variability and change rules were analyzed with classical statistics and geostatistics method for the content of soil pH value, organic matter(SOM), total nitrogen(TN), available phosphorus(AP), and rapidly available potassium(AK). The results indicated that the soil was generally acidic,and the SOM, TN, AP and AK were at medium or higher level in most areas. The variability of all soil nutrients were at moderate or higher intensity level. Spatial variation analysis showed that the exponential model was best-fitted for the 5 soil nutrients. The pH value and TN showed strong spatial autocorrelation, affected by structural and randomness factors, the spatial distribution of all these items was patchy, and the trend of stripe distribution was not obvious. There was a significantly negative correlation between the pH value and altitude,and other nutrients showed significantly positive correlation with altitude, but the correlations were different between north, central, and south Wumeng region. Elevation was an important structural factor which affected the pH value and the content of soil nutrients, but SOM, AP and AK were also disturbed by random factors.