The Spatial Pattern Of Tangutorum Nitraria Shrub Islands In North Of Ordos Plateau

Desertification is the global environment disaster, endangers our survival and development badly and is the important ecological problem that all human being must be face with together. Resource heterogeneity (vegetation heterogeneity and soil heterogeneity) is the important characteristic in desert region (arid ecosystem). The formation and development of this heterogeneity determined by the coupling mechanism of soil and vegetation to a great degree, and determined the soil degradation and restore process to a certain degree. The study object of this dissertation, "Nitraria tangutorum shrub island" is the result of thus resource heterogeneity. Because of being able to bear salt and alkali, developed root system, and being able to endure sand burying, the Nitraria tangutorum shrub island in the ecotone between Kubuqi desert and Huanghe river, is called the natural green barrier, which prevents the Kubuqi desert invading and holds back the sand soil entering the Huanghe river. In this dissertation, we use the theory and methods of landscape ecology and quantitative ecology to analyze the spatial pattern of Nitraria tangutorum shrub island. It has important theoretical value and realism significance for protectiong and restoring of the natural vegetation ecosystem in the region and even in the arid and semi-arid region, and for combating the desertification on the edge of oasis.After clustering and ordination the vegetation in the study area, analyzing the spatial pattern of the Nitraria tangutorum shrub island based on the continuous quadrats data and analyzing the point pattern and marked point pattern of the Nitraria tangutorum shrub island based on the point map data, the preliminary results were got as following:1 There are 18 groups in the study area vegetation analyzing by TWINSPAN: a) Nitraria tangutorum + Messerschmidia sibirica; b) Nitraria tangutorum + Phragmites asutralis + Mulgedium tataricum; c) Inula salsoloides+ Artemisia ordosica; d) Nitraria tangutorum + Mulgedium tataricum + Artemisia ordosica; e) Nitraria tangutorum + Agriophyllum pungens; f) Nitraria tangutorum+ Leymus secalinus; g) Nitraria tangutorum; h) Saussurea salsa + Suaeda glauca; i) Leymus secalinus + Suaeda glauca; j) Nitraria tangutorum + Achnatherum inebrians + Claux maritima + Leymus secalinus; k) Nitraria tangutorum + Leymus secalinus + Calamagrostis epigejos; 1) Nitraria tangutorum + Salsola collina; m) Nitraria tangutorum + Peganum nigellastrum; n) Nitraria tangutorum + Kalidium foliatum; o) Phragmites asutralis+ Kalidium foliatum; p) Nitraria tangutorum + Phragmites...