川西米亚罗林区主要树木生长对气候响应的差异

为分析青藏高原东缘半湿润区不同树种树木生长对气候变化的响应规律，于川西米亚罗林区海拔3000 m左右(低海拔)采集铁杉、岷江冷杉、紫果云杉，海拔4000 m左右林线位置(高海拔)采集岷江冷杉、四川红杉，共计182棵树木年轮样芯，建立了不同树种的树轮宽度年表，对不同树种的年轮指数与各月气候因子进行相关分析.结果表明： 在低海拔处，树木生长与4、5月气温呈负相关，与4、5月降雨呈正相关，受到春季干旱胁迫的影响；但树种之间存在显著差异： 铁杉的生长受春季干旱胁迫影响最严重，岷江冷杉次之，紫果云杉所受影响很小.在高海拔处，树木生长主要受生长季温度的影响，岷江冷杉年轮指数与当年2、7月最低气温呈显著正相关，与上一年10月最高气温亦呈正相关；四川红杉年轮指数与5月最高气温呈显著正相关，但与2月均温、3月最低气温呈显著负相关.近几十年青藏高原东北缘气候有干暖化趋势，如果这种趋势持续发生，低海拔紫果云杉长势将超过铁杉和岷江冷杉；高海拔处的升温更有利于岷江冷杉的生长.

Difference in responses of major tree species growth to climate in the Miyaluo Mountains,western Sichuan,China.

To explore the responses of different tree species growth to climate change in the semi humid region of the eastern Tibetan Plateau, we investigated climate growth relationships of Tsuga chinensis, Abies faxoniana, Picea purpurea at an altitude of 3000 m (low altitude) and A. faxoniana and Larix mastersiana at an altitude of 4000 m (high altitude) using tree ring width chronologies (total of 182 cores) developed from Miyaluo, western Sichuan, China. Five residual chronologies were developed from the cross dated ring width series using the program ARSTAN, and the relationships between monthly climate variables and tree ring index were analyzed. Results showed that the chronologies of trees at low altitudes were negatively correlated with air temperature but positively with precipitation in April and May. This indicated that drought stress limited tree growth at low altitude, but different tree species showed significant variations. T. chinensis was most severely affected by drought stress, followed by A. faxoniana and P. purpurea. Trees at high altitude were mainly affected by growing season temperature. Tree ring index of A. faxoniana was positively correlated with monthly minimum temperature in February and July of the current year and monthly maximum temperature in October of the previous year. Radial growth of L. mastersiana was positively correlated with monthly maximum temperature in May, and negatively with monthly mean temperature in February and monthly minimum temperature in March. In recent decadal years, the climate in northeast Tibetan Plateau had a warming and drying trend. If this trend continues, we could deduce that P. purpurea should grow faster than T. chinensis and A. faxoniana at low altitudes, while A. faxo niana would benefit more from global warming at high altitudes.