| Water resource is the key factor for harmonious development of social economy and ecology environment in western arid zone of China. Study on water consumption rule and suitable water requirement of desert shrub in arid zone was important for determining regional ecological water requirement and artificial restoration of desert plant. Some important shrubs of Haloxylon ammodendron, Tamarix leptostachys and Calligonum mongolicum planted for preventing wind and fixing sand were widely distributed in the western arid region of China. The experiment carried out in National Fukang desert ecosystem observation and experiment station. Water consumption rule and water growth characteristic of Haloxylon ammodendron, Tamarix leptostachys and Calligonum mongolicum are analyzed based on the experimental results by water balance method. The mainly conclusions are showed as follows:(1)There are widely water adaptation range for Tamarix elongate.The, peak value of water consumption would appear ahead of schedule and the persistence time would shrink when soil water futher droughty. The correlation coefficient was 0.88 between water consumption and water evaporation of every period of ten days in field water-holding capacity(θf) of 50%-60%. This illuminated that water consumption rule of Tamarix elongate was subjected to synthetically effect of meteorological factors when soil moisture was sufficiently.(2)The total dry biomass of Tamarix elongate in normal soil moisture is about 1.13 times as it in light water stress and 5.06 times as it in severe water stress. The root-crown ratio of Tamarix elongate is 0.91 under normal soil moisture condition and 1.43 when it in middle water stress. This illuminated that water stress has distinct influence in growth of dry biomass and its distribution under and above the ground of tamarix elongate.(3)The correlation of water use efficiency (water consumption of transpiration divided biomass, unit:g/kg) and water consumption of Tamarix elongate obey conic model. The best suitable water requirement was 280mm for 2 years old Tamarix elongate, and the upper limit of suitable soil water moisture for Tamarix elongate is 50%θf. The water use efficient(unit:μmol CO2/mmol H2O) further indicate that the range of suitable soil water moisture of Tamarix elongate is 40%-45.8%θf. The range of suitable soil water moisture of Haloxylon ammodendron was 35%-40%θf and this value is 39%-49%0f for Calligonum mongolicum.(4)The soil water storage is dominant factor for evapotranspiration of Haloxylon ammodendron plantation when its soil water moisture is 40.8%-50%θf. Meteorological factors determined the factual evapotranspiration of Haloxylon ammodendron plantation when the soil moisture exceeded 50%θf.(5)Base on the water balance method, Water consumption and the quota of water requirement of each plantation in different soil water grads are ascertained.Water consumption of Haloxylon ammodendron and Tamarix leptostachys under 50%-60%θf situation were respectively about 1.70 and 1.07 times than they are in 50%θf situation. The water consumption increase when soil moisture is sufficient. The water consumption of Tamarix leptostachys is 1.23 times of Haloxylon ammodendron when the soil moisture is less than 50%θf for no irrigation, which showed that Tamarix leptostachys have higher water consumption than Haloxylon ammodendron in natural condition. (6)There are evident distinction of water use efficiency (water consumption of evapotranspiration divided biomass, g/kg) for Haloxylon ammodendron, Tamarix leptostachys and Calligonum mongolicum in different soil water condition, the water use efficiency of Haloxylon ammodendron, Tamarix leptostachys and Calligonum mongolicum respectively are 1.24g/kg,.93g/kg and 2.54g/kg in 50%-60%θf, and 0.91g/kg,2.81g/kg and 0.74g/kg respectively in 40%-50%θf. It shown that Tamarix leptostachys possess higher water use efficiency. Water use efficiency of Calligonum mongolicum was higher when soil water sufficient and lowest when it wane. |
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