Abstract: Transpiration of plants has been one of the important issues of concern in plant physiological ecology and agricultural and forest science and related fields. In order to study the plant density by natural thinning and water nutrition area and water consumption of plant communitie in the natural state. This paper choice of several typical plant communities in the desert,and 4 years plots observations data are applied,and analyzed the characteristics of the water balance on plant communities that naturally sparse density,water nutrition area and water consumption of Artemisia arenaria, Ephedra przewalskii and Haloxylon ammodendron under the conditions of natural precipitation. The results showed as follows: natural sparse density of natural Artemisia arenaria and natural Ephedra przewalskii and artificial Haloxylon ammodendron is relatively stable in local. Water consumption of adult Haloxylon ammodendron forest is close with others in the same area with the 1.4 m water table in lysimeter and at 3 a seedlings. The density Haloxylon ammodendron is smaller than the others,with precipitation and transpiration,evaporation of the projection results. Under experimental conditions,the water consumption of a single plant does not mean the average water consumption of individuals in community. Water consumption of plant was studied in its natural state is more real than in the experimental conditions to a conclusion. Meaningful research is transpiration water consumption in the plant close to the wilting time,in respect of plant transpiration. Meaningful research is transpiration in plants close to the wilting time,in respect of plant transpiration,and not a few specific values,under certain water conditions. Artemisia arenaria, Ephedra przewalskii and Haloxylon ammodendron rely dieback to adapt to drought in rainfall is relatively low in the year. Some annual herbs will exit the community in the year is less precipitation,but they will enter the community in the the year in more precipitation. Artemisia arenaria will thrive when autumn rainfall is sufficient. However,the majority of seedlings of Artemisia arenaria natural death due to drought and winter difficult. Thus density of Artemisia arenaria,Ephedra przewalskii and Haloxylon ammodendron is relatively stable after natural thinning .

Key words: plant communitie, plant density, water nutrition area, water consumption, Minqin desert area