Investigating the Effects of Different Harvesting Intensities on Forage Production in Sahand Rangelands of Eastern Azerbaijan Province, Iran

Due to the decreasing trend of rangelands, many native species are vulnerable and even at risk of extinction. Therefore, seed preservation and propagation of native species of rangelands and recognition of the characteristics of grazing, drought tolerance and their production potential are very beneficial. In this study, the five species of Festuca ovina, Festuca rubra, Bromus tomentellus, Alopecurus textilis and Thymus kotschyanus, which are the key species of Sahand Rangelands in Eastern Azerbaijan province, were studied. Treatments in each block included four grazing intensities, namely 25%, 50%, 75% and the control (no harvesting). The harvest was performed during the growing season and at the beginning of the grazing season for four years (2007-2010). Results of statistical analysis showed that the effect of harvesting intensity, year and intensity by year interaction were significant for forage production of F. rubra, B. tomentellus and A. textilis (p<0.01). However, the effect of year and intensity for T.kotschyanus and the effect of year for F. ovina were not significant. Results showed that forage production of species was different in years. Higher forage production in 75% harvest intensity was obtained in B. tomentellus, F. rubra and A. textilis with average values of 15.8, 18.1 and 16.7 g/p, respectively. In latter species, forage production was much affected by climate changes rather than the harvest intensity. The highest forage production of F. ovina was obtained in light harvest. Increasing the harvest intensity may decline plant vitality. It was recommended that allowable grazing intensity of Sahand rangeland might be 25% up to 50% harvesting intensity for preserving these species.