| 摘 要： |
Critical transitions in ecosystems may imply risks of unexpected collapse under climate changes, especially vegetation often responds sensitively to climate change. The type of vegetation ecosystem states could present alternative stable states, and its type could signal the critical transitions at tipping points because of changed climate or other drivers. This study analyzed the distribution of four key vegetation ecosystem types: desert, grassland, forest-steppe ecotone and forest, in Tibetan Plateau in China, using the latent class analysis method based on remote sensing data and climate data. This study analyzed the impacts of three key climate factors, precipitation, temperature, and sunshine duration, on the vegetation states, and calculated the critical transition tipping point of potential changes in vegetation type in Tibetan Plateau with the logistic regression model. The studied results showed that climatic factors greatly affect the vegetation states and vulnerability of the Tibetan Plateau. In comparison with temperature and sunshine duration, precipitation shows more obvious impact on differentiations of the vegetations status probability. The precipitation tipping point for desert and grassland transition is averagely 48.0 mm/month, 70.7 mm/month for grassland and forest-steppe ecotone, and 115.0 mm/month for forest-steppe ecotone and forest. Both temperature and sunshine duration only show different probability change between vegetation and non-vegetation type, but produce opposite impacts. In Tibetan Plateau, the transition tipping points of vegetation and non-vegetation are about 12.1 degrees C/month and 173.6 h/month for the temperature and sunshine duration, respectively. Further, vulnerability maps calculated with the logistic regression results presented the distribution of vulnerability of Tibetan Plateau key ecosystems. The vulnerability of the typical ecosystems in the Tibetan Plateau is low in the southeast and is high in the northwest. The meteorological factors affect tree cover as well as the transition probability that occurs in different vegetation states. This study can provide reference for local government agencies to formulate regional development strategies and environmental protection laws and regulations. |
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