ABSTRACT
Rubber plantation, as a new land cover type expanding in Xishuangbanna, Southwest China, has a lifespan ranging 25 years to 40 years. Plantation development and forming of multi-layer structure comprising of canopy cover, surface cover and root system control the runoff and sediment yields dynamics. We applied Revised Universal Soil Loss Equation (RUSLE), a widely used in agricultural science predictive model, for the description of factors controlling the erosion in our case. The temporal change of erosion under growing rubber plantation was poorly studied, and RUSLE has been rarely applied in this kind of plantations. However, we believe that this approach is promising in integrative assessment of soil conservation measures in rubber system. The quantitative contribution of every part of plantation cover and roots to the protection from erosion has to be estimated for successful model application. This study aimed at assessing impact of rubber plantation ages on soil loss and relating it to canopy development and surface cover by applying RUSLE. We measured in field experiment runoff and sediment yields produced by each rainfall event in 4, 12, 18, 25 and 36 year old rubber plantations for two years (2013–2014). Monthly measurement of surface cover and understory plant cover in 2014 were completed using photography respectively. It was found that soil loss in plantations of different age varied from 52 gm–2 to 277 gm–2 with highest value appeared in mid-age (12 and 18 years) and lowest in old (25 and 36 year) rubber. We derived using our field data the Cropping management (C) factor of RUSLE in rubber plantations of different age. Thus, for the first time we quantitatively evaluated erosive potential of the rubber plantation and contribution of different factors to soil conservation. Surface cover determined erosive potential of rubber plantation while tree canopy contributed little to soil protection due to high canopy height caused by pruning activity. Sparse undergrowth under closed canopy, less litter and high decomposition rate made the rubber in mid-age the most vulnerable to erosion. Reduced herbicide application was proved to efficiently decrease soil loss to 50 gm–2. Improved soil conservation of rubber plantation should be considered by integrated land management.
