火干扰与气候因子对兴安落叶松径向生长的影响

火干扰对森林生态系统的稳定具有重要影响。以1987年5月森林火灾后的漠河林区为研究对象,按照不同的林火强度设置样地,在不同强度火干扰样地内,分别采集兴安落叶松(Larix gmelinii(Rupr.) Kuzen)的树轮样芯,建立树木年轮的宽度年表,分析不同强度的火干扰及气候对兴安落叶松径向生长的影响。结果表明:(1)不同强度火干扰对落叶松径向生长影响程度不同,轻度火干扰样地落叶松生长存在胸径加速生长期,重度火干扰样地落叶松生长存在胸径减速生长期。(2)轻度火干扰样地落叶松年轮宽度与前一年7月份和当年7月份降水量呈显著正相关(P<0.05),与前一年9、11月份和当年9月份最高气温呈显著正相关(P<0.05);重度火干扰落叶松年轮宽度与前一年7月份和当年7月份最高气温呈显著负相关(P<0.05)。(3)不同强度的火干扰对年轮宽度和气候因子的相关性影响不同,重度火干扰样地落叶松年轮宽度与气候因子的相关关系在火干扰前后的变化比轻度火干扰更加明显;该地气温过度升高不利于重度火干扰后落叶松的恢复,而对轻度火干扰后落叶松的径向生长的影响不显著。

Effect of Forest Fire Disturbance and Climate Factors on the Radial Growth of Larix gmelinii

Fire disturbance has an important impact on the stability of forest ecosystem. Taking the Mohe forest area after the forest fire in May 1987 as the research object, the sample plots were set up according to different fire intensity. The tree ring sample cores of Larix gmelinii were collected in different fire intensity plots, and the tree ring width chronology was established to analyze the effects of different intensity fire disturbance and climate on the radial growth of L. gmelinii. Different fire intensities affected the radial growth in different way. The growth of L. gmeliii was accelerated in the mild burned plots, but decelerated in the severe burned plots. After mild burning, the tree-ring width was positively correlated with the highest temperature in September, November of the previous year and September of the current year, together with the precipitation in July of the current year and previous year. However, after severe burning, the tree-ring width was negatively correlated with the highest temperature in July of the current year and previous year. Different intensity of fire has different effects on the correlation between ring width and climatic factors. The change of this correlation was more obvious after severe fire than that of mild fire. Excessive temperature rise is not help for the recovery of the L. gmelinii forest after severe burning. However, it is no obvious response on the radial growth in the mild burned plots.