西双版纳地区胶农复合系统的土壤斥水特性

Water repellency of soil in different types of rubber-based agroforestry ecosystems in Xishuangbanna

采用滴水穿透时间法与斥水指数法,测定了西双版纳地区橡胶-可可、橡胶-龙血树、橡胶-大叶千斤拔、橡胶-茶树4种较典型的胶农复合系统和单层橡胶林中的土壤斥水特性及其与土壤基本理化性质的关系.结果表明:单层橡胶林的种植增加了土壤的斥水性,其斥水持续时间显著增长,斥水指数也比其他胶农复合系统显著增大;不同土地利用方式对土壤的水力特性具有一定的影响,除了橡胶-大叶千斤拔之外,单层橡胶林中土壤的饱和导水率显著低于其他胶农复合林下的土壤饱和导水率(P<0.05).相关分析表明,土壤斥水指数与土壤饱和导水率呈显著负相关关系(P<0.05,r=-0.556);逐步回归分析表明,土壤容重与土壤质地是影响西双版纳地区胶农复合系统中土壤斥水性的主要因素.因此,构建胶农复合生态系统能够有效减轻土壤斥水性,增加土壤水分入渗,进而减轻和控制水土流失.

Water drop penetration time and water repellency index used to determine the soil water repellency and soil physicochemical properties were tested in four rubber-based （Hevea brasiliensis） agroforestry ecosystems with different interplants （Camellia sinensis, Theobroma cacao ,Flemingia macrophylla ,and Dracaena americana） and rubber monoculture in Xishuangbanna, Southwest China.The relationship between soil properties and soil water repellency was determined by Pearson correlation analysis and stepwise regression analysis.The results showed that both the persistent of soil water repellency time and the index of soil water repellency in rubber monoeulture were significantly higher than agroforestry ecosystem.Different land use patterns have certain influence on the hydraulic characteristics of the soil, except Flemingia macrophylla, the soil saturated hydraulic conductivity in rubber monoculture was significantly lower than that in rubber-based agroforestry ecosystems （P〈0.05）.Pearson correlation analysis showed that there was a significant negative relation between soil water repellency and soil saturated hydraulic conductivity （P〈0. 05, r =- 0. 556）. Stepwise regression analysis showed that the soil bulk density and soil texture were the most significant factors in controlling soil water repellency in the rubber-based agroforestry ecosystems. The results indicated that conversion rubber monoculture to rubber-based agroforestry ecosystem can effectively reduce soil water repellency and increase soil water infiltration, and ultimately control soil erosion.