Vegetation dynamic study of Kuhrang exclosure

The pressure of livestock grazing and overall utilization of rangelands have caused vegetation and soil degradation in many natural rangelands of Iran. Grazing prevention is one of the rangelands rehabilitation methods, which is effective in renovation of rangelands. The effect of 24 years of grazing protection were studied on vegetation dynamics of Kuhrang region, in two years growing seasons (2003 and 2004). Parameters from rangelands characteristics were collected and analyzed. Results showed that after 24 years livestock exclusion in Kuhrang, total inside canopy cover was higher than outside (P<0.01). Grasses and forbs were higher inside than outside (P<0.01), but shrubs were not significantly different (P>0.05). Over half of inside canopy cover belonged to decreasers and increasers, which were little or negligible outside of exclosure and 95 percent of outside plant composition belonged to invaders. Most desirable species had greater inside cover than outside(P<0.01). Klucia odoratassima, Scorzonera calyculataand Delphinium cyphoplectrumhad greatest inside canopy cover, than other forbs. More than half of inside and 95 percent of outside cover referred to decreasers and increasers. Approximately 38 and 1.2 % of inside and outside forage production belonged to decreasers and increasers respectively. Regeneration was higher outside of exclosure in Astragalus adscendens, in first year. Litter was higher inside and bare soil outside the exclosure (P<0.01). Inside and outside range condition was good and very poor, respectively.