| Abstract:
This study was aimed to investigte the effects of different harvesting intensities and year on forage production of three range species including Stipa arabica, Oryzopsis holciformis and Poa bulbosa at Koh Panj site in Kerman province during 2007 to 2010. The results were analyzed in a split plot design in time based on a completely randomized design in four replications for each species. The average forage production of Stipa arabica after 50% harvesting showed no significant difference with control treatment and 25% harvesting, indicating that this species tolereate a harvesting intensity of 50% well. However, the average forage production of Stipa 502rabica after 75% harvesting showed a decrease of 29. 1% as compared with control treatment, which was significant statistically. The average forage production of Oryzopsis holciformis and Poa bulbosa after 50% and 75% harvesting showed a decreas of 19. 75% and 33. 55% and 17. 5% and 41. 2%, respectively in comparison to the control treatment, indicating a better response of Stipa arabica to these harvesting intensities. Overall, a harvesting intensity of 50% could be recommended for Stipa arabica and 25% for Oryzopsis holciformis and Poa bulbosa. Our results showed that the growth of the study species in low rainfall years was lower thatn that of high rainfall years. Therefore, the mentioned allowable use for the study species is recommended for normal rainfall conditions. However, in addition to allowable use, range condition and trend as well as soil erodibility should be taken into account.
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