Investigation on relation between rangelands production with effective climatic parameters and drought indices in Noudushan, Iran

Although precipitation is the most important factor which effects rangeland production، but there is little information on the relationship between production and the interactions of climatic factors and specially drought indices.. In this research، the relation between production and climatic factors of rainfall، temperature، evapo- transpiration، and as well as drought indices of Standardized Precipitation Index)SPI) and Reconnaissance Drought Index (RDI) were investigated in Noudoshan Rangelands. Then the data with 33 variables were generated for different time periods of one to four months based the years of available production data. PCA was employed to decrease the number of variable and based on further component analysis، some variable were selected. To find the relation between production and climatic factors، regression analysis was used. Finally، the model with least IPE was selected as preferred model. By comparison equations based on rainfall، temperature، evapo- transpiration، and drought indices، the model resulted from RDI، selected as preferred range production estimator (R=0. 969، MARE=0. 111).