北京山区栎林的群落结构与物种组成

在北京东灵山、喇叭沟门和大海陀山地区的辽东栎(Quercus liaotungensis)林以及白龙潭地区的槲树(Q.dentata)-麻栎(Q.acutissima)混交林中共调查了43个样方，利用这些样方资料，对群落进行TWINSPAN聚类和CCA排序，以研究北京地区栎林的群落结构、物种组成以及各群落之间的关系。结果表明：本地区栎林群落结构简单，不同栎林群落的结构差异很大。利用TWINSPAN对乔木层物种进行了分类，按不同指示种划分为7类。CCA排序结果显示第一轴与海拔关系显著，主要反映了温度因子的作用；第二轴与坡向关系显著，反映了水分因子的作用。排序结果与分类结果吻合，显示了不同生境条件对群落结构和物种分布的影响。结果还显示，本地区物种丰富度低，这可能与本地区植被受人为干扰强烈有一定关系。

Community structures and species composition of oak forests in mountainous area of Beijing

Using TWINSPAN and CCA, we analyzed species composition and community structure of Quercus liaotungensis and Q. dentata-Q. acutissima mixed forests based on 43 plots from Mt. Dongling, Mt. Dahaituo and Labagoumen regions, Beijing area. Community structures of all the oak forests were simple but varied greatly in different communities. The results of TWINSPAN classification indicated that these 43 plots were clustered into 7 groups based on the flora composition of canopy layer. CCA ordination demonstrated a significant relationship between Axis 1 and altitude, indicating the importance of temperature in determining community composition. On the other hand, Axis 2 showed significant correlation with aspect, which suggested humidity may play a key role in community assembly. The consistent results of classification and ordination emphasized the importance of environmental factors in shaping community structure and species composition. The species richness of these communities was low, which likely resulted from the intensive human disturbance in this area.