干旱区油蒿种群结构和分布格局分析

Structure and Distribution Pattern of Artermisia Ordosica Population in Arid Region

对宁夏中卫市沙坡头、甘肃古浪县鸣沙咀和民勤县扎子沟这3个干旱区天然油蒿分布区的油蒿种群结构和空间分布格局进行了研究,其中根据大小结构图和存活曲线分析油蒿种群动态,用平均拥挤度m*、丛生指数(I)、聚块性指标(m*/m)、Cassie指标(CA)、扩散系数C、负二项分布中的K指标来判断格局类型并且根据双项轨迹方差法来分析格局规模。结果表明,沙坡头和扎子沟油蒿种群处于稳定阶段,鸣沙咀固定沙地和半固定沙地的油蒿种群处于增长阶段;各油蒿种群的分布格局类型为聚集分布,但是各样地聚集度大小存在着差异,具体表现为:鸣沙咀半固定沙地>鸣沙咀固定沙地>沙坡头样地>扎子沟样地;对各样地种群格局规模的分析表明格局规模存在差异。

In order to investigate the size structure and spatial distribution pattern of Artermisia Ordosica population in arid region, three typical distribution areas of Artermisia ordosica were chose as sampling plots, they are Shapotou in Ningxia Hui Autonomous Region, Mingshazui in Gulang county and Zhazigoui in Minqin county of Gansu province. The population structure of Artermisia ordosica was analyzed through survival curve and size class; the distribution pattern of Artermisia ordosica was studied through mean crowding （m＊ ）, clumping index（I）, patchiness index （m＊/m）, Cassie index （Ca）, dispersal index（C）, parameter of negative binominal （K） ; and the pattern scale was analyzed by two-term local variance. The results showed that the Artermisia ordosica population in Shapotou and Zhazigou was in a stable stage, while that in semi-fixed dune and fixed dune of Mingshazui was in a growth stage. The spatial distribution pattern of Artermisia ordosica population in different regions all were aggregation distribution, but there was difference in the cluster size. The cluster size in different regions ranked in order of Artermisia ordosica of semi-fixed dune in Mingshazui, that of fixed dune in Mingshazui, that of Shapotou and that of Zhazigou. The analysis of distribution pattern showed that there were difference pattern scales for the different sampling plots.