Estimate of Iran-Turanian zone rangelands degradation rate by measuring and suggestion Index

Rangelands degradation is the most important problem of Iran natural resources, especially in these decade. In this research for determination of the quality and quantity of rangelands degradation,9 provinces distributed within 3 main zones of Henry Pabbot’s climatic zones map of Iran territory, were selected. In these provinces, sample areas in each climatic zone were bounded on topographic maps. In the sample areas, converted rangelands to other usages, from 1955 to 1995(40 years) and then, lost and converted rangelands clarified. Considerable decline in forage production of the rangelands were also well described by comparing dry matter yield in an enclosure and the fenced area. Results showed that 9.1% of the rangelands areas, during 40 years between 1955-1995 periods, had been disappeared. Rangelands degradation in semi-desert zone with degradation index of 28.4% is lowest and in high-mountain zone with degradation index of 60.5% is the highest one. Degradation intensity in high-mountain zone is as twice as semi-desert zones. Average of degradation index for all the country zones, is 49.4% that revealed, about half of the production potential of the rangelands has been lost.