浑善达克沙地南缘榆树种群的大小结构和邻体格局

Size Structure and Neighbor Pattern of Ulmus pumila L. Population at Southern Edge of the Otindag Sandy Land

浑善达克沙地作为京津地区沙尘暴的重要沙源地引起了生态学界的广泛关注。榆树是浑善达克沙地的优势种,榆树疏林在浑善达克沙地成缀块状分布,对于该区域生态系统的整体性和多样性维持以及防风固沙等方面具有重要意义。研究浑善达克沙地南缘榆树种群的大小结构和邻体格局的结果显示:榆树种群的平均胸径为25 40cm,最小胸径为6 37cm,缺乏幼树,种群更新不良。榆树邻体格局研究显示:榆树种群呈丛分布,取样个体到最近邻体距离的平均值是7 13m,在4m以下的占55 0%,10m以下的占72 6%。两个个体互为最近邻体的榆树占了71 4%,具有成对现象,成对现象对榆树有明显影响。最后对榆树疏林存在的问题及保护措施等进行了探讨。

The Otindag Sandy Land, as an important sand source of sandstorm in Beijing and its near regions, has attracted the extensive attention of ecologists. Ulmus pumila is a native species in the Otindag Sandy Land. Ulmus pumila open forests have extensive distribution in the Otindag Sandy Land, which are important for lightening sandstorm. The article studied the size structure and neighbor pattern of the Ulmus pumila populations at the southern edge of the Otindag Sandy Land. The results showed that the mean and the minimum measured breast-high diameter(BDH) of the population were 25\^4 cm and 6\^37 cm respectively, and the population was not regenerated well recently. The neighbor pattern showed that the mean distance to the nearest neighbor was 7\^13 m, and the proportions of individuals with the distance less than 4 m and 10 m were 55\^0% and 72\^6% respectively. The percentage of individuals for which the relation of the nearest neighbor was reflexive was found to be 71\^4% in this population. The article also discussed the problems of the Ulmus pumila open forests and the possible methods for conservation.