Changes of Vegetation Cover under Drought and Wet Periods in the Flood Spreading Site and Control Rangeland of HeratYazd Province

A better understanding of rangeland vegetation cover and its variation in different years based on wetness and droughtiness fluctuations is a great importance. Economical priority setting of rangelands is based on variations in rainfall and drought patterns، because it yields to better characterization of vegetative cover. Yet a comprehensive and continuous monitoring of vegetative cover of rangelands has not been established. To study the influence of droughtiness and wetness on vegetation cover and production forage، 11 sampling areas and 3 reference areas were selected in Herat. Three 100-m transects were located 25-m apart within each sampling area. Production and cover were estimated within 10 located 2- plots along each transect. Data were analyzed using Duncan›s test Design a completely random with a factorial GLM procedure at 99% and 95% confidence levels. Results showed that the vegetation cover and production in wetness were significantly different from those in droughtiness (P<0. 01). The vegetation production and cover increased by 36. 3% and 34% respectively in the wetness compared to the droughtiness. The influence on production and cover was positive and efficient in the wetness with the average rainfall higher than the 30-yr average. Finally، the results of flood spreading increased vegetation cover and production forage in dams.