Abstract:Eremosparton songoricum is a dwarf shrub surviving in mobile or semi\|fixed sand dunes of central Asia desert. In order to detect the response of E. songoricum to micro\|habitat heterogeneity with continuous moisture gradient changes along sand dunes from bottom to top, the morphological characteristics were measured under ramet population and clonal fragment levels in two populations, one located along a riverside (population A, 46 31.09′N, 88°33.06′E, sand dune slope 15°) and another located in the center of a sand dune area (population B, 46°28.07′N, 088°33.07′E, sand dune slope 30°) in Gurrbantuggut Desert of Xinjiang, China. Height and density of ramets were investigated within twelve 1m×1m sites designed along three transects. Length, rhizome diameter (< 2 mm, 2-4 mm, 4-6 mm, 6-8 mm, 8-10 mm, 10-12 mm, >12mm), and biomass of clonal fragments were measured at 0-10 cm and 10-30 cm belowground. The results were as follows: ①At the ramet population level, the height and aboveground biomass in population A were significantly higher than those in population B, while the underground biomass (including vertical roots and horizontal rhizomes) was significantly lower in population A than population B; ②At the clonal fragment level, with the moisture content continuously reduced from the bottom to top of the sand dunes, the height and aboveground biomass reduced and the density of ramets increased in both populations, but with different intensity. Root biomass increased in population A and reduced in population B. Root length increased in both populations, but the attribution to different portions of the root system was different. At 0-10 cm belowground, population A increased root length mostly via horizontal rhizomes less than 10 mm in diameter, while population B increased mostly via horizontal rhizomes less than 6mm in diameter. The increase of small diameter horizontal rhizomes in upper slopes of sand dunes in both populations has important significance in the aspects of promoting forage behavior of the plants, escaping from adverse environmental patches, and increasing possibility of survivorship. These findings indicate that there is plasticity in response to micro\|habitat heterogeneity along the continuous moisture content gradients of sand dunes at the ramet population and clonal fragment levels.