Abstract: Investigation were carried out on vegetations of seven sections of the edge of an typical oasis of the lower reaches of the Tarim River in the summer of 2008, using the transect and quadrat method, variation of the species diversity under a habitat gradient was analyzed, using α diversity index (richness index, Shannon-Wiener index, Simpson index, Pielou index) and β diversity index (Whittacker index, Cody index), and characteristics of population distribution patterns were explored quantitatively of ten plant species in the region, using through five population distribution pattern indices (dispersion index, negative binomial parameter, mean congestion degree, clumping index and patchiness index). Results show that species diversity of the region was affected by soil moisture and soil salinity and species richness on the whole was kept at a low level. Its α diversity index followed the order of oasis > transition zone > mobile-dune, and so did β diversity index. The analysis of population distribution patterns revealed that the ten plant species all show aggregated distribution. Cluster distribution of the plant population in arid regions reflects their adaptability to the habitat.

Key words: The lower reaches of Tarim River, edge of oasis, species diversity, population distribution pattern