重庆烟区环境因子对土壤有机质含量的影响

Influences of environmental factors on soil organic matter contents in Chongqing tobacco-growing areas

为明确重庆东南部烟区土壤有机质(Soil organic matter,SOM)含量与环境因子的关系,对该烟区中1 698个取样点的SOM数据进行统计分析、构建分类回归树(CART)模型,并结合地形、气候、成土母质等11个环境因子分析该烟区环境因子对SOM含量的影响。结果表明:(1)重庆东南部烟区SOM含量呈正态分布,均值为25.82 g/kg,变异系数为30.00%,属中等变异,适宜烟草种植的区域占56.01%。(2)不同环境因子与SOM含量相关性差异较大,SOM含量与海拔、距河道高度、地形湿度指数和年均降水量呈极显著正相关,与坡度、坡长指数、径流长度和年均温度呈极显著负相关。东南坡向区域的SOM含量最高。(3)CART模型可解释SOM含量空间变异的64.80%,主要环境因子对SOM含量的重要性为海拔>年均降水量>年均温度>成土母质。

To study the relationship between soil organic matter（SOM）contents and environmental factors,1698 soil samples were collected from southeast Chongqing tobacco-growing areas,and the SOM contents in these samples were statistically analyzed.A Classification and Regression Tree（CART） model was developed to analyze the effects of 11 environmental factors such as terrain,climate and parent materials on SOM contents.The results showed that：1）SOM contents presented a normal distribution with the mean of 25.82 g/kg,and possessed moderate variability with a variation coefficient of 30.00%.A total of 56.01% of the area was suitable for planting tobacco.2） Different correlations existed between SOM contents and different environmental factors.SOM contents significantly positively correlated to altitude,height above riverway,terrain humidity index and annual average precipitation,while significantly negatively correlated to slope gradient,slope-length factor,flow path length and annual average temperature.The SOM contents in southeast slope area were the highest.3）The CART model could explain 64.80% of spatial variability in SOM contents.The importance of major environmental factors on SOM contents was in the order of：altitudeannual average precipitation〉annual average temperature〉parent material.