Physio-ecological use of water includes physiological use of water and ecological use of water. Transpiration water consumption not only belongs to physiological use of water

but also ecological use of water. Leaf water potential of C. intermedia showed high level all day

which didn't benefit maintenance of leaf water. Transpiration rates of P. simonii

S. psammophyla

C. intermedia were in the following order: S. psammophyla>P. simonii>C. intermedia.Ecological use of water includes transpiration water consumption

inter-tree evapotranspiration (IET) and soil water storage of the community. Ecological use of water of the poplar forest land was (142) mm

in which ET was 99 mm

and rainfall was 181 mm at the same period

though there was 82 mm rainfall to compensate for soil water. But rainfall mainly focused on later growth time and was behind the observation

so the results of physio-ecological use of water in the paper are a rare group of data during dry period and very important for vegetation construction of the semi-arid region.