峨眉山不同海拔冷杉径向生长对气候变化的响应

【目的】研究峨眉山不同海拔冷杉Abies fabri径向生长对气候变化的响应规律。【方法】以冷杉为研究对象,用树轮生态学的方法对峨眉山不同海拔的冷杉进行年轮采样、处理与分析,比较不同海拔冷杉径向生长特征及其与各气候因子之间的关系。【结果】年表统计数据表明,4个年表均具有较高的可靠性,可以用于树木生长与气候关系的研究。不同海拔冷杉径向生长与气候的关系具有明显的海拔差异,海拔2 400 m处冷杉径向生长与当年7月的温度呈显著正相关;海拔2 800 m处冷杉径向生长与当年4-9月的帕尔默干旱指数(PDSI)呈显著正相关;海拔2 900 m处冷杉径向生长与前一年9月和当年4月的温度呈显著负相关,与当年1-9月的PDSI均呈显著正相关;海拔3 000 m处冷杉径向生长和当年3-4月温度呈显著负相关,与当年6-7月的PDSI和当年4月平均相对湿度呈显著正相关。【结论】峨眉山高海拔的冷杉包含有更多的环境信息,对气候变化的响应也更为敏感;高海拔区域冷杉径向生长受到水分的强烈限制,而低海拔区域冷杉径向生长主要受温度影响;冷杉衰亡与气候因子的变化密切相关,随着区域气候的变暖,高海拔地区冷杉可能会进一步衰退。该研究揭示了峨眉山不同海拔冷杉生长动态及其对气候变化响应的敏感性差异,为全球气候变化背景下冷杉林的保护与适应性管理提供科学参考。

Radial growth of Abies fabri response to climate change along an altitudinal transect in the Mount Emei

【Objective】To explore radial growth trends of Abies fabri and responses to climate change at different elevations in the Mount Emei.【Method】Dendroecological techniques were used to sample, dispose and analyze tree cores of Abies fabri along an elevation gradient at four sites in the Mount Emei, and then assessed elevational trends of tree radial growth in response to different climatic factors.【Result】Statistical and highly reliability of four chronologies were all suitable for studies on growth-climate relationship. Results showed distinct elevational trends of climate-growth responses. Positive relationships were found between minimum, mean and maximum temperatures with current July and tree radial growth at the low elevation(2 400 m), and significant positive correlations were exhibited between palmer drought severity index(PDSI) from the April to September with tree growth at the middle elevation(2 800 m). Tree growth at the high elevation(2 900 m) showed significant negative correlations with temperature in the previous September and current April, and strong positive correlation with PDSI from the current January to September, whereas tree growth at the highest elevation(3 000 m) indicated significant negative associations with temperature from the current March to April, and strong positive correlations with PDSI from the June to July and relative humidity in the April.【Conclusion】At higher elevations, tree radial growth showed more environmental information and higher climatic sensitivity, and was strongly constrained by moisture availability, while tree growth was mainly restricted by temperature at lower elevations. Hence, climate change had a profound effect on the recession of Abies fabri. Climate warming in the future continue to decrease growth or increase mortality of Abies fabri at high elevations. Consequently, our findings indicated radial growth trends of Abies fabri in resonse to climate change along an elevation gradient, and it can provide a scientific basis for protection and management of fir forest under climate change.