One of the most important issues in rangeland management is the estimation of carrying capacity. To estimate range production, we need to use a large number of sample plots to clip plants in a sampling scheme; therefore, due to vast area of rangelands and time and cost limitations, direct estimation of rangeland production by sampling plots is almost impossible. Since there is a strong relationship between climatic factors and rangeland production, using indirect estimation methods of rangeland production is important. The relationship between production samples and climatic factors can be easily predicted. Present study was conducted in five locations of Spandol, Zarchak, Torogh, Aselme, and Dash, Iran in 2013. In this research, the relationships between forage production and three climate parameters including precipitation, temperature, and precipitation to temperature ratio -P/T- were investigated. For each parameter, 33 variables -periods- were considered. Stepwise regression analysis was used to select the most effective periods of precipitation and temperature. The relationship between production and March to April precipitation and November to December temperature was positive but with October to March temperature, it was negative. The relationship between production and P/T was negative in May to June and positive in January to March. In general, simultaneous of rainfall and temperature had effective roles in increasing dry matter production of grasslands in the studied areas.

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