敦煌绿洲不同生境胡杨种群结构与空间格局研究

Structure and spatial distribution patterns of Populus euphratica populations from different habitats in the Dunhuang Oasis

在敦煌绿洲天然胡杨林内设置5个样地(共计6.25hm2),应用相邻格子法,进行每木调查,结合7种聚集度指标,研究了不同生境胡杨种群的年龄结构与空间分布格局。结果表明:研究区幼苗缺失,幼树极少,年龄结构大体呈倒金字塔型,为衰退种群;林分偏老,十分稀疏矮小。不同生境胡杨种群年龄结构差异显著,其中后坑胡杨种群的年龄结构最不完整,衰退演替速度最快。除大马迷兔外,研究区胡杨表现为聚集分布,这与其自身的生理生态学特性及地形、水资源、气候、土壤等异质性生境密不可分。

In order to investigate the age structure and spatial distribution patterns of Populus euphratica populations in different habitats,five plots,totally 6.25 hm2,were established in the Dunhuang Oasis,western China.Seven aggregation indices were measured using a contiguous quadrat method and tally inventory.The results indicated that the study area was short of saplings,and juveniles were scarce,resulting in an inverse pyramidal age structure of P.euphratica populations and showing a trend of declining populations.The P.euphratica stands were aged,sparse and dwarfish.The age structure of P.euphratica populations varied remarkably among different habitats,among which,that of HK population was the most incomplete with the rapidest declining succession.In general,the spatial distribution of P.euphratica populations conformed to a clumped distribution pattern except for the DMMT population.The age structure and the spatial distribution pattern of P.euphratica populations were closely related to biological and ecological characteristics of the species and the heterogeneous environmental factors such as landform,water resources,climate and soil.