Water Stable Aggregation of Soil in Different Types of Rubber Based Agroforestry Ecosystems in Xishuangbanna

We measured the content and soil physicochemical properties of waterstable aggregates and the content of organic carbon from five rubberbased (Hevea brasiliensis) agroforestry ecosystems with different interplants (Camellia sinensis, Theobroma cacao, Flemingia macrophylla, Coffea arabica,and Dracaena americana), one rubber monoculture, and tropical rain forest in Xishuangbanna, southwest China. The results showed that when compared with tropical rain forest，the content of >5 mm and >025 mm waterstable aggregates collected from rubber monoculture significantly decreased, Meanwhile, the weight diameter (WMD) decreased by 10320%, and PAD025 increased by 36 times. When compared to rubber monoculture, agroforestry ecosystems displayed higher levels of SOC content, with the increased level in the range of 53%-6969%. As to the content of soil organic carbon in the aggregates, it was discovered that the smaller the aggregates were, the lower the soil organic carbon content was. Soil physicochemical properties（e.g., EC, bulk density and porosity）varied significantly among different sampling sites, whereas bulk density and porosity were both significantly related to the content of >025 mm and >5 mm waterstable aggregates and WMD. The above results showed that soil quality has been improved in rubberbased agroforestry ecosystems in comparison to rubber monocultures.