Soil organic carbon in pure rubber and tea-rubber plantations in South-western China

Abstract: Rubber tree (Hevea brasiliensis) plantation is a major land use practiced in Xishuangbanna of south-western China. Effects of rubber plantation (RP) and tea-rubber intercropping (TRI) systems on soil organic carbon pools were evaluated by recording changes in soil organic carbon in an age sequence of 12-, 20-, 26-, and 40-year old plantations. Labile organic carbon (LOC) increased in surface soils (0-10 cm) with aging of rubber plantation and tea-rubber intercropping stands. Total organic carbon (TOC) in the soils did not change between stand ages of 12 and 20 years, however it decreased at the 26-year old stand. The TOC increased remarkably in tea-rubber intercropping tea-row soils but remained low in the rubber plantations and tea-rubber intercropping rubber-row soils at the 40-year stand. The TOC did not show much difference between in tea-rubber intercropping rubber-row and rubber plantations at the 40-year stand, but these values were much lower than that in tea-rubber intercropping tea-row soils. The LOC and its turnover rate, and the ratio of LOC:TOC in tearubber intercropping rubber-row soils were lower than those in tea-rubber intercropping tearow soils and rubber plantations. This study suggests that tea-rubber intercropping tends to sequestrate higher atmospheric carbon in soils than rubber monoculture through increased organic carbon pools in the tea-row soils and reduced organic carbon turnover rates in the rubber-row soils.