西双版纳地区胶农(林)复合系统对土壤团聚体的改良作用

The improvement of soil aggregates by building rubber-based agroforestry ecosystems in Xishuangbanna,Southwest China

研究了西双版纳地区3种典型胶农(林)复合生态系统(橡胶-茶叶、橡胶-可可和橡胶-大叶千斤拔)以及单层橡胶林的土壤团聚体稳定性特征以及土壤结构特征.结果表明:与单层橡胶林相比,胶农(林)复合系统的土壤物理性质得到明显改善,表现在土壤容重降低,土壤孔隙度增大,并且土壤容重和土壤孔隙度均与>2 mm和>0.25 mm水稳定性团聚体以及与各团聚体稳定性指标呈极显著相关性;除了橡胶-茶叶复合系统外,橡胶-可可、橡胶-大叶千斤拔复合系统>2 mm和>0.25 mm水稳定性团聚体含量极显著增多,并且随着土壤深度的增加而下降;相比较单层橡胶林,胶农(林)复合系统团聚体稳定性指标平均重量直径(MWD)和平均几何直径(GMD)均显著增加,分形维数D值则减小,说明构建胶农(林)复合系统后团聚体更加稳定,土壤质量明显得到改善;逐步回归和差异性检验分析表明,MWD可作为该研究地区最佳土壤结构稳定性指标.

Stability and phisical properties of the soil aggregates from three rubber-based（ Hevea brasiliensis）agroforestry ecosystems with different interplants（ Camellia sinensis,Theobroma cacao,Flemingia macrophylla）,and a monoculturerubber forest were studied in Xishuangbanna,Southwest China. The results showed that the physical properties of rubber-based（ Hevea brasiliensis） agroforestry ecosystems presented lower soil bulk density,and higher soil porosity in comparison with the monoculture ecosystem. Bulk density and porosity in rubber agroforestry ecosystems were both significantly related to the contents of water-stable aggregates（ 2 mm and 0.25 mm） and stability indices of the aggregates; The contents of water- stable aggregates（ 2 mm and 0. 25mm） in Hevea brasiliensis-Theobroma cacao and Hevea brasiliensis-Flemingia macrophylla ecosystem（ except the Hevea brasiliensis-Camellia sinensis agroforestry ecosystem） were much more than that of the monoculture ecosystem,and decreased by the soil depth; Compared to the monoculture ecosystem,MWD and GMD in rubber-based agroforestry ecosystems were both significantly increased,while dimension value（ D） was significantly decreased.The results proved that soil aggregates and soil quality were getting more stable and significantly improved after the construction of rubber-based agroforestry ecosystems.Stepwise regression and variance analysis indicated that mean weight diameter（ MWD） can be considered as a good index for the soil structure stability in this area.