季节增温方式对小兴安岭红松针阔混交林演替的潜在影响

应用林窗模型LINKAGES对小兴安岭红松针阔混交林在不同季节增温方式下的未来演替过程进行了模拟预测.以温度增加5℃、降水无明显变化作为未来变暖气候的模拟假设,共设计3种气候变暖方式预案,分别为冬季增温幅度大于夏季、冬季与夏季增温幅度相同以及冬季增温幅度小于夏季.模拟结果表明,当冬季增温幅度大于夏季时,小兴安岭现存林分的演替受气候变暖的影响相对最小,树种组成仍然能够保持较为稳定的针阔混交林状态;当冬季增温幅度小于夏季时,现存林分的演替受气候变暖的影响最显著,树种衰退最迅速.可见,小兴安岭针阔混交林的演替与未来的增温方式关系密切,上限温度是现存树种能否继续存活的重要决定因子.

Potential impact of seasonal temperature increase pattern on the succession of coniferous-broadleaved Korean pine mixed forest in Xiaoxing'an Mountain

With LINKAGES model, a simulation prediction was made on the future succession process of coniferous-broadleaved Korean pine mixed forest in Xiaoxing'an Mountain under different seasonal temperature increase patterns. The future getting-warmer climate was assumed as a 5 degrees C increase of monthly mean temperature and an unobvious change of precipitation. Three climate change patterns were designed, i.e., temperature increasing range was greater in winter than in summer, the same in the two seasons, and greater in summer than in winter. The simulation results indicated that when the temperature increasing range was greater in winter than in summer, the succession of the present stand in Xiaoxing'an Mountain was relatively least affected by temperature increase, and the tree species composition still remained a relatively stable coniferous-broadleaved forest state. On the contrary, when the temperature increasing range was greater in summer than in winter, the succession of present stand was most significantly affected by temperature increase, and the tree species degenerated fastest. It could be concluded that there was a close relationship between the succession of coniferous-broadleaved Korean pine mixed forest in Xiaoxing'an Mountain and the future climate change patterns. The maximum temperature could be the key factor determining the viability of the present tree species.