Phenological response of tropical plants to regional climate change in Xishuangbanna, south-western China

The phenology of temperate plants is vulnerable to climate change. Yet, the phenological responses of tropical plants to climate change are still unclear. In this study, temporal trends (1973-1999) of four phenological events (budburst, growing season, flowering and flowering duration) were studied among 21 plant species in Xishuangbanna Tropical Botanical Garden (south-western China). Fourteen species (67%) showed significant phenological trends during the study period. Seven species (33%) presented delaying trends in budburst (average 1.4 d y(-1)) and such trend was more likely to be presented in those that started budburst earlier in the dry season. Four species (19%) showed trends of extension in growing season (average of 3.5 d y(-1)). These vegetative events appeared to be mainly influenced by increasing temperature. Rainfall showed little effects directly, however, the effects of temperature seemed to largely depend on the moisture condition. Flowering duration of five species (24%) was shortened by average 2.1 d y(-1) which was most likely to be the result of the decline in sunshine duration during the rainy season. Our results suggest that the phenology of tropical plants has changed significantly in response to the regional climate change but these reactions are somewhat different from those of temperate plants.