Foliar Ecological Stoichiometric Characteristics Of Typical Plants In The Mu Us Desert

In arid and semi-arid regions, plants grow in the environment of water shortage and low soil nutrient contents. After a long period of acclimation and evolution, plants have formed their own unique ecological stoichiometric characteristics. The foliar carbon, nitrogen and phosphorus stoichiometric characteristics of desert plants, and the adaptative strategy in response to the environment and nutrient utilization situation of different functional groups of plants which were reflected on the foliar carbon, nitrogen and phosphorus stoichiometric characteristics, the researches of these questions will help to enrich the researches on the field of plant ecological stoichiometry in desert ecosystem in China. Due to the spatial heterogeneity of different desert areas, the research results of different desert areas are not the same, and at present, the research on the ecological stoichiometry of plant leaves in the process of vegetation restoration in the desert ecosystem is particularly scarce.28 typical plants which grow in the moving dunes, semi-fixed dunes and fixed dunes of the Mu Us Desert were selected as the research objects to be investigated their foliar carbon, nitrogen and phosphorus stoichiometry. The main conclusions are as follows:(1) The growth of the typical plants in the Mu Us Desert was more limited by P, such as Artemisia ordosica, Hedysarum mongolicum, Thermopsis lanceolate and Leymus secalinus. The foliar C, N and P contents ranged in 356.36-525.85 mg/g,9.30-54.47 mg/g and 0.54-3.59 mg/g, with the mean being 445.62 mg/g,26.37 mg/g and 1.54 mg/g, and the foliar C/N, C/P and N/P ranged from 8.04 to 47.52, from 113.81 to 820.15, from 6.83 to 40.68, with the mean being 18.80,353.17 and 19.54. As compared with those at global scale and national scale, the foliar N/P in the research area was significantly higher.(2) In the Mu Us Desert, monocotyledons, for instance, L. secalinus, Cleistogenes squarrosa, and Stipa glareos, may be more dominant in the resource competition. The foliar average C contents were higher in leguminous plants than in non-leguminous plants; the foliar average C contents were higher in shrubs than in perennial herbs and annual herbs; the foliar average N contents and P contents were higher in annual herbs than in shrubs and perennial herbs; the foliar average N contents and P contents were higher in dicotyledons than in monocotyledons while C/N and C/P were lower; the foliar average N contents and P contents were higher in C3 plants than in C4 plants while C/N and C/P were lower. The result indicated that, the ability to adapt to the adverse environment of leguminous plants and shrubs in the Mu Us Desert was stronger, therefore leguminous plants and shrubs were more suitable for growing in drought and other stress conditions. The ability to obtain nutrients of annual herbs, dicotyledons and C3 plants was stronger, and the absorption and utilization efficiency of N and P of dicotyledons and C3 plants was higher and their growth rate was faster.(3) During vegetation restoration, plants showed different survival strategies, and the trend of vegetation succession was limited by nutrients. With the sand dunes stabilization, the foliar average C contents, N contents and P contents of shrubs, perennial herbs, monocotyledons, C3 plants and non-leguminous plants tended to decline while annual herbs tended to rise; the foliar average C contents and N contents of dicotyledons, C4 plants and leguminous plants tended to rise while the foliar average P contents tended to decline. The result indicated that, the environmental adaptability and the ability to obtain nutrients of shrubs, perennial herbs, monocotyledons, C3 plants and non-leguminous plants weakened while annual herbs strengthened; the environmental adaptability and the ability to obtain N of dicotyledons, C4 plants and leguminous plants strengthened, while their ability to obtain P weakened.The research results revealed the foliar C, N, P composition characteristics and distribution pattern of 28 typical plants in the Mu Us Desert, and the adaptative strategy in response to the environment of high temperature, less rainfall and low soil nutrient contents and nutrient utilization situation of the plants in different functional groups, and survival strategy of plants in different functional groups in 3 different types of sandy lands. This study can provide reference for the further research C, N and P ecological stoichiometric characteristics of desert ecosystem.