Estimation of long-term forage production of steppe rangelands of Fars province based on climatic factors parameters

Climatic factors are the most important factors affecting vegetation growth and production. The impact of each of these factors in each region varies depending on the vegetation type. The effect of climatic factors (rainfall and temperature) on the production of grazed plant species at 6 steppe sites in Fars province over a ten year period (1998 to 2007) was investigated. 60 plots of 2 square meters along 4 transects of four hundred meters were used to measure cover and production was measured by cutting and weighing method in 15 plots along transects. Then, using regression relationship between canopy cover (percent) and production (kg ha-1), the residual plot yield was calculated for that year. Important climatic indices analyzed in this study are: annual rainfall, growing season rainfall (March to June), plus and earlier rainfall, annual temperature, July temperature, August, maximum and minimum temperatures. The results showed that the average canopy cover was 6.3% and the average yield was 128.5 kg / ha and among the different vegetative forms of shrubs had the highest percentage of cover and production and wheat had the lowest cover and production percentage. Among the important climatic indices, annual rainfall and August temperature at all sites and the growing season rainfall at all sites except for the desired site were the most effective indicators on forage production and showed a positive and significant correlation with forage production.