PRELIMINARY STUDY ON THE LANDSCAPE ECOTYPE CLASSIFICATION IN MAOWUSU SANDLAND AND THE BIODIVERSITY OF ITS SHRUB COMMMITIES Effect of Water Supply Change on Chlorophyll Fluorescence of Four Dominant Plants in Maowusu Sandland Study on the Water Balance in Three Dominant Plants with Simulated Precipitation Change in Maowusu Sandland Study on Evolution of Air-seeding Vegetation and Habitat in Maowusu Sandland STUDY ON THE EFFECT OF SIMULATED PREGIPITATION CHANGE ON THE PHYSIOLOGICAL ECOLOGY PROCESS FOR ARTEMISIA ORDOSICA SEEDLINGS IN MAOWUSU SANDLAND The Influence of Environment Factors on Photosynthetic and Transpiration Rate of Amorpha fruticosa in Maowusu Sandland Effect of different water conditions on growth and morphology of Artemisia ordosica Krasch.seedlings in Maowusu sandland