三峡大老岭地区主要木本植物分布的地形格局

AN ANALYSIS OF THE TOPOGRAPHICAL PATTERNS OF THE CHIEF WOODY SPECIES AT DALAOLING MOUNTAIN IN THE THREE GORGES REGION

基于对三峡大老岭地区山地森林群落的深入调查，选择样方乔木层中重要值大于１．００的１９０种木本植物，依次根据生活型和植物在群落中的地位分成常绿针叶树种、常绿阔叶树种、落叶阔叶的建群树种、伴生种和珍稀树种共６组，采用ＤＣＣＡ排序分析各组植物种在复合地形梯度上的空间格局特征；然后分别统计常绿或落叶的乔木或灌木４组物种沿具体海拔高度的整体分布特征。研究反映了６个生态种组之间在山地地形上鲜明的格局差异，并显示了山地常绿落叶阔叶混交林带上常绿和落叶种类数量变化的梯度特征和相对间断性。

The 190 woody species found in a substantial survey of mountain forest communities in Dalaoling Mountain of the Three Gorges region with the importance values greater than 1. 00 were chosen for analysis in the paper. The species were classified into 6 groups according to their lifeform and status in the communities:evergreen conifer tree species, evergreen broad-leaved tree species, deciduous broad-leaved dominant tree species, companion tree species, pioneer tree species and rare species. DCCA was applied to analyze the spatial patterns of these groups on the compound topographical gradients. The holistic distribution characteristics of 4 species groups:evergreen vs. deciduous and tree vs. shrub species along the altitudinal gradient were then analyzed. This was designed to show gradients of change and discontinuities of evergreen vs. deciduous species numbers perpendicular to the mountain mixed forest zone of evergreen and deciduous species.