亚洲树轮平均敏感度分布特征及其影响因素

Variations of mean sensitivity of tree rings in Asia and their influencing factors

树轮敏感度是指示树轮对气候变化敏感程度的重要统计参数,研究大尺度树木敏感度的分布特征及其影响因素有助于理解树木生长和气候的相互关系.本文使用来自国际树轮库(ITRDB)的573条树轮宽度记录,研究亚洲树轮敏感度的分布特征及可能的影响因素.结果表明:在干旱地区和温度较低的区域,树木的平均敏感度更高,降水对敏感度的影响强于温度.平均敏感度随海拔的上升表现出下降-上升-下降的波动变化.这种波动与降水随着海拔表现的上升-下降-上升的变化相吻合,说明海拔变化导致的降水改变可能是导致平均敏感度变化的重要因素之一.不同树种生理性状的差异导致其敏感度差异较大,祁连圆柏、西藏白皮松等阳生树种由于耐旱性而具有更高的敏感度,而阴生树种如云杉属和冷杉属则敏感度较低;老龄树可能具有更高的敏感度.

Mean sensitivity (MS) of tree ring is a key index representing the sensitivity of tree rings to climate. Understanding the variation of MS and its influencing factors at a large area is helpful to understand the interaction between tree growth and climate. We used 573 tree-ring width chronologies in Asia from the International Tree Ring Date Bank (ITRDB) to examine the variation of tree-ring sensitivity and potential influencing factors. The results showed that the MS of trees was high in the arid regions and cold regions. Precipitation was more important than temperature in diriving MS. Consistent with the pattern of up-down-up for precipitation, MS showed a down-up-down fluctuation with increasing altitude, indicating that precipitation affected by altitude was a key climate factor for the MS. MS had great difference due to different physiological traits among tree species. Light-adapted species, such as Juniperus przewalskii and Pinus gerardiana, had high MS due to drought tole-rance. Shade-adapted species, such as Picea and Abies, had low MS. Old trees may have high MS.