Shade tolerance and suitability of tree species for planting in rubber plantations

Abstract

The rapid increase in rubber monoculture in Xishuangbanna has resulted in  extensive damage to its local ecosystem. To decrease the negative effects, the concept of the ecological-economic rubber plantation (EERP) system was proposed. The EERP entails intercropping rubber plants with other economically significant plants, which would not only decrease the ecological impact of the rubber plantation, but also maintain and potentially increase its profitability compared with rubber monocultures. In order to select the appropriate species and intercropping pattern in the EERP system, we compared the photosynthetic parameters of five  economically important trees (Swietenia mahagoni, Coffea arabica, Mesua ferrea, Myristica yunnanensis and Paramichelia  baillonii) under four irradiance levels. The optimal irradiance intensity of C. arabica and M. yunnanensis was approximately 40%, and these species can be planted in the understory of an 8- to 15-year-old rubber forest. Adult S. mahagoni, M. ferrea and P. baillonii grow taller than the rubber trees, and their seedlings also show superior performance in 100% irradiance than in other irradiances. Thus, in an EERP, these valuable trees could be planted  adjacent to rubber plantations but on sites that are economically and  environmentally marginal for rubber production.