川西亚高山林线岷江冷杉和红杉对气候变化的响应

为揭示川西亚高山林线优势树种岷江冷杉（Abies fargesii var.faxoniana）和红杉（Larix potaninii）径向生长对气候变化的响应差异。通过树木年轮生态学的方法，研究了岷江冷杉和红杉径向生长与年均温的分异现象、生长衰退以及应对严重干旱事件的抵抗力和恢复力稳定性，并结合限制岷江冷杉和红杉径向生长的主要气候因素进行了分析。结果表明：（1）温度是限制林线岷江冷杉径向生长的主要气候因素，而限制红杉径向生长的主要气候因素是降水；（2）岷江冷杉的径向生长与年平均温度的变化趋势一致，红杉在20世纪90年代后径向生长呈现出下降的趋势，与年均温的升高出现分异；（3）1800-2019年间，岷江冷杉出现生长衰退2次，红杉出现生长衰退5次，相同的时间内，红杉的衰退频率高于岷江冷杉；（4）岷江冷杉对严重干旱事件的恢复力相比升温前有所增强，抵抗力相比升温前下降明显，红杉对严重干旱事件的抵抗力和恢复力相比升温前均呈现出下降的趋势。可为川西亚高山林线的植被动态变化预测和历史区域气候重建提供参考。

Responses of Abies fargesii var. faxoniana and Larix potaninii to climate change in the subalpine timberline of western Sichuan, China

This research aimed to reveal the differences in radial growth responses of the dominant tree species Abies fargesii var. faxoniana and Larix potaninii to climate change in the subalpine timberline of western Sichuan, China. Based on dendrology methods, the main climate factors limiting the radial growth of these two species were used to analyze the divergence between radial growth and annual average temperature, growth decline, resistance and recovery against severe drought. The results showed that (1) temperature was the main climate factor limiting the radial growth of A. fargesii var. faxoniana in the timberline, while precipitation was the main climate factor limiting the radial growth of L. potaninii. (2) The change trend of radial growth of A. fargesii var. faxoniana was consistent with the average annual temperature, while the radial growth of L. potaninii showed a decreasing trend since the 1990s, which was divergent with the increase of averagely annual temperature. (3) From 1800 to 2019, two periods of growth decline occurred for A. fargesii var. faxoniana, while five periods of growth decline occurred for L. potaninii, indicating that the frequency of L. potaninii was higher than that of A. fargesii var. faxoniana during this time. (4) For A. fargesii var. faxoniana, the resilience against severe drought increased, while the recovery ability decreased after warming; for L. potaninii, the resistance and recovery ability against severe drought showed a decreasing trend compare to before warming. This study can be helpful for predicting vegetation dynamics and reconstructing the historical climate in the subalpine timberline in western Sichuan, China.