不同树龄雪岭云杉径向生长变化特征与模拟研究

目的 利用天山北坡中段的雪岭云杉（ Picea schrenkiana）资料,建立上、下林线的树轮宽度年表,并进行树木径向生长特征分析。 方法 将下线雪岭云杉按树龄划分为幼龄组、中龄组与老龄组,计算不同树龄雪岭云杉树木胸高断面积增长量（BAI）,以此建立ARIMA模型,模拟分析雪岭云杉径向生长过程。 结果 与上树线相比,下树线的树轮宽度年表中蕴含着更多的气候信息。ARIMA模型模拟的3个树龄组雪岭云杉BAI变化中,中龄组观测值与模拟值拟合效果最优（R2 = 0.832）。因ARIMA模型基于单变量自身变化趋势进行建模,故结合现有气象数据进行气候突变前后生长趋势变化分析,发现幼龄雪岭云杉实测BAI总体上增长显著,但增速逐渐减缓。 结论 中、老龄雪岭云杉BAI在气温突变前呈减小趋势,在气温突变后,中龄云杉BAI趋于平稳,老龄云杉BAI由减小趋势转变为增加趋势。     

Growth responses of subalpine fir (Abies fargesii) to climate variability in the Qinling Mountain, China

Dendroecological techniques have been employed to investigate the relationship between subalpine fir (Abies fargesii) growth and climatic variability throughout its elevational range on both south and north aspects in the Qinling Mountain of Shaanxi Province, China. Correlation analyses indicate that early spring and summer temperatures are the principal factors limiting its growth in the low- and middle-elevation distributional areas. In the high-elevation areas, it is the summer precipitation that affects A. fargesii radial growth. The previous year August and November temperatures show positive correlation with the radial growth in the low- and middle-elevation distributional areas of the south aspect, and in the high-elevation areas, precipitation in previous November has significantly negative influences on the radial growth. The previous year's temperature and precipitation have no significant effects on the radial growth of the fir trees in the north aspect. Thus, the growth of the subalpine A. fargesii responds differently to climatic conditions along the elevational gradient and in different aspects.