玉龙雪山3个针叶树种在海拔上限的径向生长及气候响应

Response of radial growth of three conifer species to climate at their respective upper distributional limits on Yulong snow Mountain

树木生长对气候变化的响应是国内外研究的热点。选择滇西北高原玉龙雪山海拔分布上限3个主要树种(长苞冷杉(Abies georgei)、丽江云杉(Picea likiangensis)和大果红杉(Larix potaninii Batal var.macrocarpa Law)),对其径向生长特征进行研究,构建差值年表,并分析其与温度和降水的相互关系。研究结果表明:(1)温度和降水均为玉龙雪山海拔上限树木生长的主要影响因子,但不同树种响应的时期和关系存在差异;(2)大果红杉生长主要受限于生长初期(5—6月)的水热条件,主要表现为与当年5月、6月以及生长初期(5—6月)的平均温呈显著正相关,以及与当年5月、6月以及生长初期的降水呈显著负相关;(3)长苞冷杉生长主要受限于生长初期(5—6月)的水分条件,表现为显著负相关,同时生长盛期(7—8月)温度的升高有利于其径向生长;(4)丽江云杉的生长则主要受限于生长季开始以前的气候条件,与上年12月以及当年5月的平均温呈显著负相关,与当年1月的降水呈显著正相关。本研究的结果可为气候变化对滇西北高原树木生长影响的研究提供参考,并为该地区历史气候重建提供科学基础。

The Northwestern Yunnan Plateau is located on the southeastern margin of the Tibetan Plateau, which is an area sensitive to climate change. In this area, forests have remained undisturbed due to their remote location, and many tree species have grown to their upper distributional limits. Accordingly, it is an ideal location for dendroelimatological study. Although some dendrochronological research has been carried out on the Northwestern Yunnan Plateau, few studies have been conducted on Yulong snow Mountain, which is a typical snow mountain and supports growth of the main tree species in the area. In order to detect the response of tree growth to climate change on the Northwestern Yunnan Plateau, we used the tree-ring width index of three major conifers, Abies georgei, Picea likiangensis, and Larix potaninii Batal var. macrocarpa Law, at their upper distributional limits on Yulong Snow Mountain. Specifically, we focused on the characteristics of residual chronologies and the relationships between radial growth and climatic factors （temperature and precipitation）. We aimed to identify the main climatic factors limiting tree growth in the area and detect differences in growth responses to climate among the studied species. The following results were obtained （ 1 ） Temperature and precipitation were the main factors affecting tree growth at the upper distributional limits on Yulong snow Mountain, but the effects varied according to tree species. （2） The radial growth of L. potaninii Batal var. macrocarpa Law was mainly limited by temperature and precipitation during the early growing season （May--June） of the current year, and was positively and negatively correlated with temperature and precipitation in May and June, respectively. （3） Precipitation during the early growing season of the current year was the main factor limiting the radial growth of A. georgei, with a significantly negative correlation between the residual chronology and May--June precipitation, whereas higher temperature during the growing season （July--August） of the current year positively affected its growth. （4） The radial growth of P. likiangensis was mainly limited by climatic factors before the start of the growing season, showing a significantly negative correlation between growth and mean temperature of the previous December and current May, and a significantly positive correlation between growth and precipitation during the current January. Our research represents a reference tree-ring study of the Northwestern Yunnan Plateau, and can provide a scientific basis for climate reconstruction in the area.