Shi Zhi-Hua, Zhu Hua-De, Chen Jia, Fang Nu-Fang, Ai Lei
Ministry of Agriculture Key Laboratory of Arable Land Conservation of Middle and Lower Reaches of Yangtze River, Huazhong Agricultural University, Wuhan 430070, China.
Ying Yong Sheng Tai Xue Bao. 2012 Apr;23(4):889-95.
Taking the Wulongchi catchment of Danjiangkou in central China as a case, the soil moisture regime in the observation period from April to October, 2008 was divided into different dry-wet time periods by two way indicator species analysis (TWINSPAN), and the environmental factors that had significant effects on the spatial pattern of soil moisture in different dry-wet time periods were selected by forward selection and Monte Carlo tests. The redundancy analysis (RDA) was adopted to identify the relationships between the distribution pattern of soil moisture and the environmental factors in different time periods, and the partial RDA was applied to quantitatively analyze the effects of environmental factors, spatial variables, and their interactions on the variation pattern of the soil moisture. The soil moisture regime in the observation period was divided into 7 types, and grouped into 4 time periods, i. e. , dry, semi-arid, semi-humid, and humid. In dry period, land use type was the dominant factor affecting the spatial pattern of soil moisture, and the soil thickness, relative elevation, profile curvature, soil bulk density, and soil organic matter content also had significant effects. In semi-arid period, soil thickness played dominant role, and land use type, topographic wetness index, soil bulk density, and profile curvature had significant effects. In semi-humid period, topographic wetness index was the most important affecting factor, and the land use type and the sine value of aspect played significant roles. In humid period, the topographic compound index and the sine value of aspect were the dominant factors, whereas the relative elevation and catchment area were the important factors. In the four time periods, there was a better consistency between the spatial distribution pattern of soil moisture and the environmental ecological gradient. From dry period to humid period, the independent effects of environmental factors on soil moisture pattern decreased but were still in dominant, the independent effects of spatial location had less change and maintained at lower level, while the interactions between environmental factors and spatial location contributed more and more.
以中国中部丹江口的伍龙池流域为例，采用双向指示种分析（TWINSPAN）方法将2008年4月至10月观测期内的土壤水分状况划分为不同的干湿时段，并通过向前选择和蒙特卡罗检验筛选出对不同干湿时段土壤水分空间格局有显著影响的环境因子。采用冗余分析（RDA）识别不同时段土壤水分分布格局与环境因子之间的关系，并运用偏冗余分析定量分析环境因子、空间变量及其交互作用对土壤水分变异格局的影响。观测期内的土壤水分状况分为7种类型，归为4个时段，即干旱、半干旱、半湿润和湿润时段。干旱时段，土地利用类型是影响土壤水分空间格局的主导因素，土壤厚度、相对高程、剖面曲率、土壤容重和土壤有机质含量也有显著影响。半干旱时段，土壤厚度起主导作用，土地利用类型、地形湿度指数、土壤容重和剖面曲率有显著影响。半湿润时段，地形湿度指数是最重要的影响因素，土地利用类型和坡向正弦值起显著作用。湿润时段，地形复合指数和坡向正弦值是主导因素，相对高程和集水面积是重要因素。在这4个时段，土壤水分空间分布格局与环境生态梯度之间具有较好的一致性。从干旱时段到湿润时段，环境因子对土壤水分格局的独立作用减小但仍占主导，空间位置的独立作用变化较小并维持在较低水平，而环境因子与空间位置的交互作用贡献越来越大。
