Abstract: The natural plants in a desert-oasis ecotone play an important role in protection of the ecological environment of the oasis. Understanding of how human activities like land use affect the natural plants is crucial for the evaluation of structure and function of the ecotone. Ecological stoichiometry is widely used in identification of nutrient deficiency and evaluation of ecosystem stability. Three species in the south region of the Taklimakan Desert, Tamarix ramosissima, Alhagi sparsifolia and Karelinia caspia were selected to study the effects of land use types and intensities on total carbon (C), nitrogen (N), phosphorus (P), C∶N, C∶P and N∶P of plant leaves. In this study, the average elemental content of the three species was 385.94 mg·g^-1, 13.62 mg·g^-1, 1.49 mg·g^-1, 30.33, 294.01 and 9.69, respectively for C, N, P, C∶N, C∶P and N∶P. Compared to other communities in arid lands or in global scale terrestrial ecosystems, plant C and P contents were normal, while N content was lower than in other regions. The land use types, intensities and their interactions significantly affect most indicators. The plant C, N, P and their ratios were significantly different among different desert sites of the ecotone. The plant nutrient levels also differed after cultivation. For example, plant C usually decreased, while N and P increased after cultivation. The more intensive the cultivation activity, the greater the magnitude of N and P increase observed. The nutrient changes also depended on species. Correlation between soil nutrient and plant nutrient levels was not significant in T. ramosissima, and K. caspia, while plant N and P of the three species were closely correlated. Generally, plants collected from the southern region of the Taklimakan Desert were lacking N, but the deficiency was partially alleviated under certain land uses. Along with the changes in intensity of the land use in this region, we speculated that the plant stoichiometry would vary in different magnitudes.

Key words: desert-oasis ecotone, ecological stoichiometry, Taklimakan Desert, land use