气候因子对不同竞争等级华北落叶松径向生长的影响

Response of Radial Growth of Larix principis-rupprechtii Mayr.to Climate at Different Competitive Levels

以六盘山地区华北落叶松(Larix principis-rupprechtii Mayr.)为研究对象,使用交角竞争指数将华北落叶松划分为不同的竞争等级,采用树木年轮学的分析方法建立不同竞争等级华北落叶松树轮宽度年表,分析不同竞争强度下气候对华北落叶松树木径向生长的影响。结果表明:(1)在该区域,竞争等级越小的树木生长能力越强;(2)竞争压力的增加会增强树木径向生长对前一年生长季末期(10月份)的降水以及当年生长季初期(5、6月份)的温度的敏感性,但树木径向生长对生长前期(3月份)温度的敏感性随着竞争压力的增加而降低;(3)标准化降水蒸散指数(SPEI)仅对在中等竞争压力下的树木生长具有显著影响,主要表现在上一年10月份对树木径向生长的促进作用和当年5月份的抑制作用。

We selected Larix principis-rupprechtii Mayr.in the Liupan Mountains area as a research object,dividing different competition levels of L.principis-rupprechtii Mayr.by using the intersection angle competitive index,established tree-ring width chronology of L.principis-rupprechtii Mayr.by using the analysis method of dendrochronology,to analyze the response of Larix principis-rupprechtii Mayr.radial growth to climate at different competition intensities.The results showed:(1)The lower the competition level,the stronger the growth ability of trees in this region.(2)The sensitivity of tree radial growth to precipitation in October at the end of the growing season and temperature in May and June at the beginning of the growing season increased with the increase of competitive pressure,but the sensitivity of tree radial growth to temperature in March at the beginning of the growing season decreased with the increase of competitive pressure.(3)SPEI only had significant effects on tree growth under medium competition pressure,mainly promoting radial growth in October of last year and inhibiting radial growth in May of the current year.