Water is one of the most limiting environmental factors for successful rehabilitation in Mongolia. In this study, variations in biomass allocation, water use effi ciency (WUE) and carbon isotope composition of fi ve woody species (Caragana arborescens Lam., Hippophae rhamnoides L., Larix sibirica Ledeb., Pinus sylvestris L. and Ulmus pumila L.) seedlings were investigated in an open fi eld nursery. There are diverse responses of species under drought conditions. Hardwood species, U. pumila, showed the lowest photosynthetic WUE and carbon isotope composition among fi ve species but demonstrated superior morphological response in terms of root weight ratio (0.49±0.02) and root biomass allocation compared to other species (p