滇西北石卡雪山2个针叶树种森林上限径向生长对温度和降水的响应

基于树木年轮学的理论和方法,建立滇西北高原石卡雪山森林上限丽江云杉(Picea likiangensis)和高山松(Pinus densata)差值年表,运用响应函数研究其与气候因子的关系,进而阐明影响滇西北高原针叶树种径向生长的主要气候因子,并利用冗余分析(RDA)进一步分析并验证树木生长与温度和降水的关系。研究结果表明:石卡雪山森林上限针叶树种径向生长主要受温度影响,温度和降水对树木生长有滞后效应,2个树种对气候响应存在差异。具体表现为(1)丽江云杉径向生长受温度和降水的共同作用,与上年10月平均最低温呈显著负相关,与上年11月平均最高温以及当年7月温度呈显著正相关,上年8月和当年5月降水抑制其生长;(2)高山松径向生长与上年10月平均温和平均最高温、11月平均温呈显著正相关,与当年7月平均温和平均最高温呈显著负相关,与降水未达到显著相关水平;(3)冗余分析与响应函数分析结果基本一致,进一步证明该方法能够有效量化树木径向生长与气候因子的关系。能够为气候变化背景下的滇西北高原森林生态系统管理与保护提供理论依据。

Radial growth response of two conifers to temperature and precipitation at upper forest limits in Shika Snow Mountain, Northwestern Yunnan Plateau

The Northwestern Yunnan Plateau, located in the southeastern edge of the Tibet Plateau, is a region sensitive to global climate change. Multiple tree species form the upper treeline on different snow mountains within the region, making the mountains ideal sites for dendrochronological studies. However, climate-growth relationships in the Shika Snow Mountain (one of the typical snow mountains in the region) are unclear, and improved understanding of tree growth response to climate change in Shika is fundamental to predicting growth under future climate change. To detect growth response of multiple species to climate change, we developed residual chronologies of Picea likiangensis and Pinus densata at upper distributional limits in Shika Snow Mountain, Northwestern Yunnan Plateau, using dendrochronology. We used response function to study relationships between residual chronologies and climatic factors, aiming to elucidate the main climatic factors affecting radial growth of conifers in the Northwestern Yunnan Plateau. To further analyze and verify the relationships between radial growth and temperature and precipitation, redundancy analysis was applied. Results showed that temperature was the main factor influencing conifer growth at the upper forest limits in the Shika Snow Mountain; temperature and precipitation have a lag effect on tree radial growth and the two conifers responded differently to climatic factors. Specifically:(1) The radial growth of P. likiangensis was affected by temperature and precipitation, showing a significantly negative correlation with mean minimum temperature of the previous October, and a significantly positive correlation with mean maximum temperature of the previous November and temperature of the current July. Precipitation of the previous August and current May inhibited growth of P. likiangensis. (2) The radial growth of P. densata was significantly and positively correlated with mean temperature and maximum temperature of the previous October and mean temperature of the previous November, and showed a significantly negative correlation with mean temperature and maximum temperature of the current July. However, no significant correlation was detected between growth and precipitation. (3) The redundancy analysis presented similar results as the response function analysis, further indicating that the method can effectively quantify the relationship between tree radial growth and climatic factors. This study provides a theoretical basis for the management and protection of forest ecosystems in the Northwestern Yunnan Plateau faced with climate change.