芦芽山阴坡华北落叶松-云杉天然次生林群落特征的海拔梯度格局

Spatial Distribution of Larix principis-rupprechtii-Picea spp.Secondary Forests Along Elevation Gradients on North Facing Slope of Luya Mountain,Shanxi

沿海拔2000～2600m设置了20块乔木样地,100个灌草样方,在群落调查的基础上应用双向指示种(TWINSPAN)和去趋势对应分析(DCA)等方法对芦芽山自然保护区阴坡落叶松—云杉群落特征随海拔的变异规律及灌草群从垂直分布格局与环境因子的关系进行了研究。结果表明:随海拔升高,乔木的树高、胸径与冠幅在波动中下降,而其活枝下高、林分胸高断面积及密度呈增大趋势;灌木层的多样性指数与均匀度指数均随海拔升高显著下降,丰富度指数下降趋势则不明显;上述3个指数在草本层的变化均不明显;研究立地的灌草植物可划分为13个群丛类型,其空间分布主要是海拔和土壤水分综合作用的结果;各灌草物种均有其最优分布海拔,灌木的分布上限位于海拔2550m,海拔2200～2400m是灌草物种组成发生明显变化的区域。

Altitudinal changes in community characteristics of Larix principis-rupprechtii-Picea spp.secondary forests on Luya Mountain were investigated in 20 tree plots and 100 shrub and herb subplots,and the relationship between the spatial distribution of shrubs and herbs and environmental factors was analysed by using TWINSPAN classification method and Detrended correspondence analysis（DCA）.In the arbor layer,tree height,diameter at breast height（DBH） and crown width decreased with increasing altitude,while height under living branch,stand basal area and density increased.In the shrub layer,biodiversity index and evenness index decreased significantly with increasing altitude,and richness index exhibited an unobvious change.In the herb layer,the above indices did not change obviously along the altitude gradient.Shrub and herb communities were classified into 13 associations,and altitude and soil moisture were the main factors influencing their spatial distribution.Each shrub species or herb species had its optimum elevation range,and the upper distribution limit of shrubs was 2 550 m,and the composition of shrubs and herbs changed significantly in the altitude range of 2 000-2 400 m.