عنوان مقاله [English]
Improving vegetation cover in arid and semi-arid regions can be controlling desertification and the production of cellulosic materials by afforestation, in these circumstances, human survival and habitat, as well as wildlife, also provided too. For afforestation in arid and semi-arid regions, it is necessary to selection of appropriate species and pay attention to their ecological and eco adaptation needs. Drought resistance mechanisms include water use efficiency in many forest species for a stay of drought condition have been utilization. On the other hand, water requirements and the effects of drought stress on ecological adaptation are important for this plants. Through lysimetry experiments and determination of water requirement for many forest species including Saxual (Haloxylon aphyllum) and several species of eucalyptus (Eucalyptus camaldulensis, E. microtheca E. sarjentii, E. leucoxyloni, E, saligna and E. flocktoniea), there were considered and adaptation mechanisms for survival in dry conditions were studied for them. Among the mentioned species, Saxual had the lowest water requirement and the most resistant species to drought stress. This species had a higher water use efficiency to drought stress.