Abstract: 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.

Key words: wetland vegetation, dominant population, pattern, Sanggan River watershed, Shanxi