Abstract: Water is the most important constraint factor for the establishment of vegetation in arid ecosystems.Therefore,the availability of extra water resources is the prerequisite for the establishment of artificial vegetation in desert ecosystems.It is not sagacious to establish artificial vegetation in such arid ecosystems when there are no adequate extra water resources.The improvement of desert vegetation should be realized mainly by the protection of Current plants and the establishment of semi-artificial vegetation.The general process for the inventory of plant population is to investigate: ①currently,is there any natural population of the targeted plant species? ②Historically,was there any natural population of the targeted plant species? ③Do the natural conditions meet the requirement of the recruitment of the targeted plant population? and ④What is the probability for man to provide ecological resources? Enclosure protection of current vegetation and the establishment of semi-artificial vegetation are the main approaches for the recruitment of desert vegetation,while the protection of underground water resources is a radical step.

Key words: Root biomass, Pinus yunnanensis forest, Stand age, Soil depth