北京城区公园的植物种类构成及空间结构

对植物种类构成及空间结构的研究，可为公园植物多样性保护及公园的科学管理提供重要依据.采用分层随机抽样调查法，调查了北京市五环以内的53处公园，共记录维管束植物96科283属492种.基于研究区乔、灌、草共21个调查项目的大量数据及相关统计分析，对北京城区公园绿地各层植物的常见结构型式进行了阐述.结果表明：北京城区公园植物中，本地种占5386%，植物属的区系地理分布很广泛，优势植物的优势性明显；研究区大部分公园的草本植物种类较为丰富、盖度较高，而灌木盖度偏低、树冠下的灌木也偏少，乔灌植物种类丰富度和密度不高，乔木冠幅、胸径、灌幅及乔灌高度基本在2级水平，但乔木冠层结构比较丰满、受光良好、生长状况良好，灌木叶层缺失不明显.通过相关分析和北京市园林绿化史调研结果推测，北京城区公园植物种类构成及其空间结构主要受园林设计、植物引种、种植管理的影响.

Species composition and spatial structure of plants in urban parks of Beijing.

By the method of stratified random sampling, the species composition and spatial structure of the plants in 53 parks in Beijing urban area were investigated, aimed to provide basic information for the protection of plant diversity in the parks and the management of the parks. A total of 492 plant species belong to 96 families and 283 genera were recorded. Based on the data of 21 investigation items about the trees, shrubs, and grasses in the study area and related statistical analyses, the plant structural patterns commonly seen in the green space of the parks of Beijing urban area were introduced. Among the plants in the parks, native species occupied 5386% of the total. The chorological composition of the genera embraced broad kinds of geographical elements in China, and the predominance of dominant plants was remarkable. In most green patches of the parks, herbaceous species were more abundant and had higher coverage, shrubs had relatively low coverage and were less beneath tree canopy, and trees and shrubs had lower species richness and density. The canopy breadth and the diameter of breast height of trees as well as the breadth of shrubs and the heights of trees and shrubs were basically at the second grade, but the canopy structure of the trees were better, with good conditions of sunlight and growth. The crown missing of the shrubs was relatively low. It was suggested from correlation analyses and document survey of Beijing parks construction history that park landscape design, alien species introduction, and cultivation management were the main factors affecting the species composition and spatial structure of the plants in Beijing urban parks.