外来树种华北落叶松引种对秦岭森林群落的影响

Effects of exotic tree species Larix principis-rupprechtii introduction on forest community in Qinling Mountains of Northwest China

采用样地调查法对比研究了秦岭火地塘林区外来树种华北落叶松人工林与乡土树种华山松人工林及华山松天然次生林群落特征差异。结果表明:华北落叶松人工林群落与华山松天然次生林群落的相似性系数仅为0.11,华山松天然次生林与华山松人工林的物种数量均明显高于华北落叶松人工林(P<0.01);华山松天然次生林和华山松人工林乔、灌、草层的Margalef指数、Simpson指数、Shannon-Wiener指数和Pielou均匀度指数均显著高于华北落叶松人工林(P<0.001),而前两者之间灌木层和草本层的4个多样性指数的差异不显著(P>0.05);华北落叶松人工林的自然构成系数最低(0.3),华山松天然次生林的自然构成系数最高(5.2),华山松人工林的自然构成系数为3.5,三者存在极显著差异(P<0.001)。说明外来树种华北落叶松引种造成秦岭森林群落物种丰富度、植物多样性和林分自然化程度降低,自然次生演替或乡土树种人工林较外来树种人工林更有利于林下植被的恢复。

By the method of plot investigation, a comparative study was made on the differences in the community characteristics among the exotic tree species Larix principisrupprechtii plantation, indigenous tree species Pinus armandii plantation, and P. armandii secondary forest in Huoditang forest area of Qinling Mountains. The similarity coefficient between L. principisrupprechtii plantation and P. armandii secondary forest was only 0.11, and the species number in the P. armandii secondary forest and P. armandii plantation was significantly greater than that in L. principisrupprechtii plantation （P〈0.01）. The Margalef index, Simpson index, ShannonWiener index, and Pielou evenness index in the arbor, shrub, and herb layers of P. armandii secondary forest and P. armandii plantation were significantly higher than those in L. principisrupprechtii plantation （P〈0.001）, but the four diversity indices in the shrub layer and herb layer in P. armandii secondary forest and P. armandii plantation had less difference （P〉0.05）. The compose index （CI） was the lowest （0.3） in L. principisrupprechtii plantation, 3.5 in P. armandii plantation, and the highest （5.2） in P. armandii secondary forest, showing a significant difference among the three forest types （P〈0.001）. This study indicated that exotic tree species introduction led to the decrease of species abundance, species diversity, and stand’s naturalized degree in the forest community in Qinling Mountains, while natural secondary forest succession or indigenous tree species plantation were more beneficial to the restoration of understory vegetation than exotic tree species plantation.