基于Vaganov-Shashkin模型的太白红杉径向生长对气候要素的响应

Response of Larix chinensis radial growth to climatic factors based on the Vaganov-Shashkin model

利用采自太白山南坡药王殿、北坡上板寺的太白红杉树芯样品分别建立树轮宽度年表,运用Vaganov-Shashkin模型揭示秦岭太白红杉径向生长对各气候要素的响应.结果表明:生长季(4—8月)的温度、生长初期的降水量以及7、8月的降水量是限制秦岭地区太白红杉生长的主要气候因子.良好的温度条件有利于太白红杉的生长,但生长初期的降水量会抑制太白红杉的生长;7、8月的降水量对秦岭南坡和北坡太白红杉的影响差异明显,该时段内丰富的降水量对北坡太白红杉的生长具有促进作用,而对南坡太白红杉的生长产生一定的限制作用;同一坡向、不同海拔采样点树木径向生长与气候因子的响应结果同样存在差异,高海拔采样点太白红杉的生长需要的温度条件低于低海拔采样点,但对土壤湿度的需求大于低海拔采样点.生长开始日的早晚对太白红杉树轮宽度的形成影响很大,而生长结束日仅与南坡采样点树轮宽度之间呈显著相关.

Tree ring width chronologies were established by core samples of Larix chinensis collected from the Herb Temple in southern slope and the Shangban Temple in northern slope of Taibai Moun- tain, respectively. Based on the Vaganov-Shashkin model, this paper discussed the responses of Qinling Mountains L. chinensis＇ radial growth to various climatic factors. The research found that the temperatures of growing season （from April to August）, the precipitation in initial stage of growth and in July to August were the main climatic factors limiting the growth of L. chinensis. The higher temperature was favorable, for the growth of trees, but precipitation in the early stage of growth in- hibited it. L. chinensis from the southern and northern slope of Qinling Mountains showed different responses to precipitation in July to August, in which abundant precipitation promoted the growth of L. chinensis in the northern slope, while inhibiting the growth in the southern slope. Even in the same slope, sampling sites with different altitudes brought discrepant responses of trees＇ radial growth to climatic factors. The L. chinensis at higher altitude needed lower growth temperature than that at lower altitude, but the former demanded greater soil moisture than the latter. The start day of growth had a great influence on the radial growth of L. chinensis, however, the end day of growth only affected that on the southern slope.