Studies On Spatial Distribution Pattern Of Hedysarum Scoparium Population And Community Characters In The Northeastern Ulan Buh Desert

With the helps of various statistical analyses we studied the spatial distribution pattern of population, community characters as well as the genet characters and the ramet population characters of the Hedysarum scoparium in the northeastern Ulan Buh Desert. The results we obtained from the study are as following:1. The contiguous grid quadrats have been applied to sample the field data. The methods such as S2/ˉx ratio t-test and five aggregate indices (CI, M*, PAI, CA, K) have been used to analyze the spatial distribution pattern of Hedysarum scoparium population in different habitats. The results showed that the distribution pattern was clustering in different habitats, but the intensity was different. In addition, the analysis of distribution pattern was done according to development stages. From saplings to adults, the degrees of clump decreased. Pattern scale is a subject to reflect the size of block aera. Hedysarum scoparium population in the fixed dunes formed bigger patch than the semi-fixed dunes, and its pattern intensity was also bigger in the fixed dunes.2. Plant species composition in Hedysarum scoparium community is simple, and the structure level is obvious, including 2 levels: shrub layer and herb layer. Diversity of species in the herb layer is higher than the shrub layer. But there is similarity that the value of the species in the fixed dune is more diverse compared with the semi-fixed dunes. Whole coupling character of mensuration indicates that 7 species in Hedysarum scoparium community have slightly positive relationship. But for species pairs'coupling character, the majority are negative, in other word, the coupling character are very small.3. Hedysarum scoparium is a typical clonal plant, which can produce new ramets through clonal growth; this research showed that each Hedysarum scoparium genet included 21 ramets on average, and the most were 51, which indicated that Hedysarum scoparium had strong planar expansion ability to migrate spatially and occupy the new habitat. Compared with the ramet population in the semi-fixed dunes, the ramet population in the fixed dunes exhibited higher ramet density, but smaller average ramet spacing. It testified clonal architecture of Hedysarum scoparium in the fixed dunes inclined to the phalanx, but in the semi-fixed dunes, it inclined to the gurilla. It is also a strategy of Hedysarum scoparium to adapt different environment.