Abstract: The spatial pattern of plant population is a key to study the relationship between plants and environment. It is a manifestation of the stability and life history strategies of plant population. To clarify finescale spatial pattern of Phragmites australis population in salt marsh of Yangguan, Dunhuang, we investigated their populations in four different sites across a gradient of wet zone, light salt zone, heavy salt zone, and desert zone. The Ripley K(d) function analysis method was used to examine the finescale spatial pattern of P. australispopulations and its ecological adaptation. The results showed that, from wetland to desert, the coverage, density, height, and above ground biomass of P. saustralisshowed a significant downward trend. The gap size significantly increased, while population density increased initially and then decreased. Across the gradient, the strategies of spatial expansion for P. australis population were changed from the clumped distribution as the main type, nonclumped distribution (random or regular distribution) as the supplement, to the random distribution as the main type and non-random distribution (clumped or regular distribution) as the supplement. Our results clarified the spatial pattern and driving factors of P. australis population in the inland riverine wetland, and served as a case study for further understanding ecological adaptation mechanism of clonal plants, and theoretical basis for scientific conservation and management of the inland riverine wetlands in the arid region.

Key words: stand age, carbon storage, biomass, allocation, karst.