中文摘要：

以石羊河中游荒漠河岸植被优势种群沙蒿（Artemisia arenaria）为研究对象,采用点格局分析法,对垂直于河道不同距离梯度上沙蒿种群的空间格局和空间关联性进行了分析。结果表明：①随着垂直于河道方向距离的递增,沙蒿种群由增长型逐渐演变为衰退型;②垂直于河道不同距离梯度上沙蒿种群的格局特征为,在相对小的尺度上聚集分布特征明显,随尺度的增加聚集性减弱并逐渐表现出随机分布的格局特征,但距离河道近的沙蒿种群聚集强度大于距离河道远的种群;不同距离梯度上,沙蒿种群均表现出幼体聚集分布,成体随机分布的格局特征;③垂直于河道不同距离梯度上沙蒿种群不同龄级之间的关联性表现出异质性。距离河道近的沙蒿种群中,形体差异大的植株之间具有正关联性,反映了互利的生态关系;距离河道较远的沙蒿种群中,形体差异小的植株之间具有负关联性,反映了互斥的生态关系;其他龄级植株之间没有表现出明显的关联性。

英文摘要：

Artemisia arenaria is an important plant species of fixing sand in the Shiyang River Basin, Gansu Province. In this study, some sample plots with different distance away from the river course of the Shiyang River were delimited to analyze the spatial distribution pattern of Artemisia arenaria population. In the plots, the height, crown breadth and spatial relevancy of all the different-aged Artemisia arenaria plants were recorded. The point pattem a- nalysis was used to analyze the spatial distribution pattern and relevancy of the plants in different plots. The results were as follows ： （ 1 ） Artemisia arenaria population was in a decrease trend with the increase of distance away from the river course; （2） Artemisia arenaria population was in a significant aggregation distribution pattern at relatively small scale, the aggregation distribution pattern decreased gradually with the enlargement of scale, a random distri- bution occurred, and the aggregation degree near the river course was higher than that far away from the river course. At different distance, young plants grew in an aggregation pattern, but the adult ones in random pattern; （3） There was a positive spatial relevancy among the high plants near the river course, but a negative one among the short plants far away from the river course.