The effect of climatic conditions on vegetation cover and production in steppe rangelands(Case Study: Alavijeh and Khondab-Isfahan province)

In this study, the effects of three important climate factors including rainfall, temperature, and relative humidity were studied on vegetation cover and forage production for ten years (1997-2007) as well as in the Alavijeh and Khondab steppe rangelands, Isfahan province, in 2013. The results of the eleven-year study in steppe rangelands showed that shrubs and grasses had the highest and lowest vegetation cover and production and the average vegetation cover and average production were calculated to be 12% and 124.5 kg per hectare. The results of simple regression analysis showed that in steppe rangelands, the total vegetation cover is affected by annual rainfall and temperature, so that vegetation cover increased with increasing annual rainfall and decreasing temperature. The total production in the study rangelands is affected by annual rainfall, cold season rainfall, and minimum temperature. The long-term production was calculated to be 55 and 176.6 kg per hectare for the Khondab and Alavijeh sites, respectively. According to the results of stepwise regression, using climatic factors, the relative humidity with temperature of December and annual rainfall was identified as the best equation to estimate the annual vegetation cover in the Khondab and Alavijeh sites. In the Khondab site, the temperature of November and total rainfall from March to May was identified as the best equation to estimate the annual production. However, in the Alavijeh site, the total rainfall of growing season, minimum temperature of March, and temperature of May and December was the best. Therefore, the impact of climate conditions on vegetation cover and annual production and different life forms are not similar in the steppe rangelands.