Impact of rubber plantation age on erosive potential studied with USLE model

Rubber (Hevea brasiliensis) plantations have a lifespan in the range of 25-40 years. We aimed at assessing soil losses in rubber plantations of different ages (4, 12, 18, 25 and 36 years old) and relating erosion risk to surface cover and fine root density by applying the Universal Soil Loss Equation (USLE) model. We measured runoff and sediment yields in rubber plantations in Xishuangbanna, Southwest China during 1 year. Fine root density, surface cover and understory plant cover were measured monthly. Annual soil loss in different plantations varied from 0.33 to 2.80 t ha(-1). Combined annual cover, management and support practice factor CP from the USLE model varied with the growth phase of rubber in the range of 0.006-0.03. Monthly CP factor was related exponentially with the surface cover. Inhibited undergrowth and high decomposition both contributed to decreasing surface cover in mid-age rubber resulting in highest erosion risk phase.