疏勒河中下游绿洲胡杨种群结构与动态研究

通过在疏勒河中下游天然胡杨林区设置7个样方6.852 4 hm²,采用相邻格子法和动态数量值,分析胡杨种群的结构与动态特征。结果表明:中下游及不同生境胡杨种群年龄结构差异显著。中游幼苗缺失,幼树不多,中树最多,占总数的72.15%,大树较多,老树甚少,年龄结构呈正态分布型,林分年轻、稠密、高大,每公顷胡杨总数是下游的13.45倍。下游幼苗缺失,幼树极少,中树较多,大树最多,大、老树占总数的62.54%,年龄结构呈倒金字塔型,林分偏老,稀疏、矮小。中下游均为衰退种群。胡杨种群存活曲线基本接近Deevey I型,为下降种群;且存活率幼、中树高于大、老树,中游明显高于下游。种群数量动态计算表明,幼、中树动态量值为负值,大树、老树为正值,但胡杨总体表现为衰退的结构动态关系。总之,研究区胡杨未来因幼苗缺乏而趋于衰退演替,且下游衰退演替的速度更快。

Study on Population Structure and Dynamics of Populus euphratica in the Middle and Lower Reaches of the Shule River Basin Oasis, Hexi Corridor

Based on the investigated and selected research plots of 6.8524 hm2 of Populus euphratica which were divided into 566 subplots in 2009 in the middle and lower reaches of the Shule River Basin Oasis,Hexi Corridor,all the trees whose stems are over 2.5 cm in DBH were identified,measured,tagged and mapped by using quaclrat method and every-tree measuring method.The size and age structure and the survival curves were created and the dynamics quantitative estimate was analyzed with field data.The results indicat...