After the rubber boom: good news and bad news for biodiversity in Xishuangbanna, Yunnan, China

摘要

The expansion of rubber plantations in northern Southeast Asia over the last 20years displaced shifting cultivation and tropical forests. In Xishuangbanna, SW China, rubber occupied 22% of the area by 2010, reducing lowland forest to scattered fragments, with severe impacts on plants, animals, and ecosystem services. The rubber price has declined steeply since 2011, but consequences for forest biodiversity have not previously been explored. We use a new approach for vegetation mapping, combining phenological information with object-based classification, to produce land-use maps for 2002, 2010, 2014, and 2018. During 2002-2018, forest cover declined continuously, from 71 to 52% of the land area, while rubber increased from 11 to 24% by 2014, before declining to 21% by 2018. Other farmlands also declined while tea plantations increased. Forest patch number increased 8-fold during 2001-2014, while patch size decreased 10-fold, but these trends were partly reversed after 2014, with the loss of numerous small (1ha) patches. Most larger (10ha) patches in 2018 were forest throughout the study period, but many smaller patches are secondary. Currently, 20% of Xishuangbanna is in protected areas. Unprotected forest is disproportionately on steep slopes at high altitudes, while biodiversity is highest in valleys and at low altitudes, where only smaller patches remain, creating challenges for conservation planning. We recommend that all the largest patches are preserved, plus smaller patches selected for their biota, and that forest restoration is used to restore connectivity and buffer small patches of high conservation value.