阿尼玛卿山不同海拔祁连圆柏树轮宽度年表特征对比分析

The Characteristics of Tree-ring Width of Sabina przewalskii Kom for Different Elevations in the A'nyêmaqên Mountains

利用阿尼玛卿山地同一坡面的不同海拔高度获取的4组树木年轮样本,建立了不同海拔梯度的树轮宽度指数年表.各年表中较高的信噪比SNR和样本总体解释量EPS表明,各采样点树木中含有较多的共同环境信息,从低海拔向高海拔的递减反映了高海拔小生境差异对树木生长影响较大;平均敏感度和标准差随海拔升高呈先递减后递增的趋势.气候因子对整个坡面的树木生长起着主导影响,其中气温的作用更大一些.可靠年表的平均序列长度随海拔升高变短,表明树木生长是沿着山坡逐渐向上迁移的.不同海拔树轮宽度可靠年表间高频变化一致,10 a滑动的高生长和低生长的不一致则反映了低频变化的差异.相关分析表明,生长在森林上限的树木对环境因子的响应滞后于森林下限,生长在最大降水高度附近的树木对环境因子响应的敏感性最低.

Tree-ring cores were taken from four sites at different elevations of the same slope on the A＇nyiêmaqên Mountains, where the environment ,is sensitive and the relative height is large. Four tree-ring width chronologies Sabina przewalskii Kom were determined using standard dendrochronological methods. The more signal-to-noise ratio （SNR） and agreement with population chronology （ESP）, the stronger common environment information of tree in different sampling sites held. These values decreasing with increasing elevation reflects that micro-environment had great influence on tree-growth at high elevation. However, mean sensitivity （M. S. ） and standard deviation （S. D. ） show a decrease from the low limit to middle-high elevation, with an increase above the middle-high elevation. The first principal component accounting for 61. 495% of the variance in all chronologies shows that the mainly dominant factor is consistent in the whole slope. Also＇correlation and response analyses between PC1 and climatic factors reveal that climatic factor is the most importance to tree growth in the whole slope, especially temperature. The mean sequence of dependable tree-ring width standard chronology among sampling sites decreased with increasing altitude, and trees appeared during warm weather. These indicate that appearance and up-growth of tree gradually move up along the slope with the coming of warmth phase. High correlation between tree ring-width dependable chronologies at different elevations of these sampling sites shows that the high-frequency changes among tree ring chronologies are consistent, but there is some diversity in the low-frequency changes of tree ring chronology. The lag-orrelation analysis and correlation analysis after lowpass filter of dependable standard chronologies between upper-limit and low-limlt suggest that the tree growing at the upper-limit lags behind that at the low-limit in response to environment factors. The amplitude of vibration of tree-ring width indices changing with elevation shows that tree growing in the maximal height of precipitation has the minimal sensitivity in response to environment factors.