水蕨(Ceratopteris thalicroides)种群的分布格局

Spatial Pattern of Ceratopteris thalicroides Populations

对国家二级重点保护野生植物水蕨(C.thalicroides)部分分布区进行了野外调查,共发现13个野生水蕨种群.水蕨种群的生境主要为海拔低于1000m的水稻田.各种群分布面积较小,种群内植株数和密度相差很大.采用方差/均值比率、t值检验、负二项参数、扩散型指数、Cassie指标、丛生指标、平均拥挤度和聚块性指标等方法,研究了种群内植株数大于50株的10个野生水蕨种群的分布格局,并运用邻接格子样方法进行了格局规模检验,结果表明水蕨种群分布格局类型为聚集分布型,但各种群聚集分布强度不同.水蕨孢子及无性繁殖体近距离传播是造成其聚集分布的主要原因.人为因素的作用导致水蕨种群的灭绝.

Ceratopteris thalicroides is an endangered plant in China and is categorized as the Second National Key of Protected Wild Plants. A total of 13 populations were found in our field investigation. C. thalicroides is mainly distributed in the rice field and the populations were small and isolated. The populations were different in individual numbers and densities. The spatial patterns of 10 populations were studied using the following measures: variance/ mean ratio, t-value, negative binomial parameter, index of dispersal, index of Cassie, index of clumping, index of mean crowding and index of patchiness. The aggregated distribution of C. thalicroides populations was indicated in the present study. However, the degrees of aggregation were different in the investigated populations. The aggregated distribution was mainly caused by the poor dispersal of spores and asexual propagators. The extinction of C. thalicroides populations mainly resulted from human activity.