山西桑干河流域湿地植被优势种群分布格局研究

根据野外调查的样地资料，应用方差/均值比（扩散系数）的t检验、聚集指数、平均拥挤度、聚块性指数、Green指数和负二项分布的聚集强度等方法，研究了山西桑干河流域湿地植被优势种群的分布格局并分析格局形成的原因，并用相关分析比较了6个指数间的关系，结果表明：这些植物的分布格局皆属于聚集分布，但它们的聚集强度有差异。聚集强度最大的是沙棘和柽柳，聚集强度最小的是小车前和车前，由于它们均分布于河漫滩或者河床地势较高处，土壤水分含量较低，仅仅在洪水季节短时间有积水存在，不是典型的湿地植物。典型的水生植物泽泻、莎草、轮藻、芦苇、香蒲、慈姑，湿生植物水葱、藨草等，它们的聚集强度居中，对水分有着较强的依赖性，均分布于流水较缓的河道，或者濒临河道的积水处。此外，多年生的莎草、芦苇、香蒲、水葱、藨草等主要依靠无性繁殖扩大种群分布范围和密度，这也是它们服从聚集分布的原因之一。本研究还说明方差/均值比率法是一种较好的分析种群分布格局的方法。

Patterns of dominant populations of wetland vegetation in Sanggan River Watershed, Shanxi

Based on the data from the field,the patterns of dominant populations of wetland vegetation in Sanggan River watershed,Shanxi were studied by using v/m(dispersal index) ratio t-test,clump intensity,mean crowding,patchiness index,Green's index and the intensity index k of negative binomial distribution and the cause involved with the pattern was analyzed.The relationships among the six methods were analyzed by correlation coefficient.The results showed that the patterns of those populations were all clumped,however,they were different in clump intensity,among which the species with the biggest of clump intensity were Hippophae rhamnoide,and Tamarix chinensis,and the species with the smallest of clump intensity were Plantago minuta and Plantago asiatica,respectively,because they distributed in the taller physiognomy of flooding plain or riverbed where the moisture content of soil was lower and had flooded only in the flooding season,moreover,they were not typical wetland plants.The clump intensities of the typical hydrophytes including Alisma orientale,Cyperus glomeratus,Chara sp.,Phragmites communis, Typha angustifolia,Sagittria trifolia and hygrophyte including Scirpus tabernae-(montani) and Scirpus triqueter were mediate,the reason was they were depended on moisture of soil strongly and they distributed all in that the water flow was slowly in riverway or nearing the seeper of riverway.Moreover,perennial plants,such as Cyperus glomeratus,Phragmites communis,Typha angustifolia,Scirpus tabernaemontani,Scirpus triqueter and so on,relied on mostly asexual reproduction to extending population distribution and increasing density,this was the other reason that they followed clumped.Finally,the result indicated that the application of variance/mean ratio was one of the better methods to analyze population pattern.