Response of alpine vegetation to climate changes in the Nanling Mountains during the second half of the Holocene

摘要

Studying the response of vegetation to past climate changes may help better predict the potential impacts of future climate changes on the terrestrial ecosystems. Here we present a pollen record that covers the second half of the Holocene from the Nanling Mountains, southern China. Our record reveals six cooling events occurring during 5600-4800, 4400-4100, 3800-3300, 3200-2900, 1600-1400, and 500-380 cal yr BP in this area. These cooling events broadly correspond to the episodic weakening of the Asian summer monsoon and the Bond events in the North Atlantic realm, suggesting a common forcing mechanism. Given that temperature has an important effect on the vertical distribution of alpine vegetation in this area, the projected future warming may lead to a large upward shift of the upper forest line and a threat to the life of alpine tree species on the Nanling Mountains. For example, under the RCP8.5 scenario, mean surface air temperature is projected to increase by 4.9 degrees C by the end of this century. This magnitude of warming definitely would result in the disappearance of Tsuga chinensis in this area.