Research on Seasonal Dynamic Changes of Drought Resistance of Ailanthus altissima in Arid Valleys of the Minjiang River

There are 161 km of arid valleys(170 km2) in the Minjiang River.Xerophil shrubs and grasses are dominant in this area.However they play a significant role in the soil and water conservation in the watershed,and provide important reference for converting farmland to forestor grass land project as it is very difficult to grow trees in the arid valleys.Researches were conducted on drought-resistant physiological characteristics of Ailanthus altissima.The results showed that its water content,evaporation ratio,WSD,RWC decreased under the drought stress;Integrated assessment on the drought resistant index of Ailanthus altissima indicated that the integrated drought resistant index was the highest(3.828) in September,followed on July(3.591),August(2.945) and June,and was the lowest(only 1.489) in May.