studying the vegetation changes of natural rangelands in inche shorezar of agh ghala, north golestan province, iran

studies on vegetation changes of rangelands under grazed and non-grazedconditions are of great importance in the range management planning programs. to determinethe change process of vegetation, this study was performed in inche shorezar site of golestanprovince for nine years (1997-2005). the vegetation parameters were measured every year inseveral fixed plots inside and adjacent of exclosures. the canopy cover of each species wasestimated in each plot. forage production was randomly measured on one meter square plotsin each year using the clipping and weighing method. correlations between canopy cover ofspecies and growth forms with the rainfall of different months and periods were calculatedusing spss software. results showed that total canopy cover in 2005 was significantly higherthan 1997 both inside and adjacent of exclosures which has been mainly related to increasedannual plant cover but the perennial canopy cover was decreased in these years. perennialspecies of (class i) did not grow inside the fixed plots. cover of increasers (class ii) specieswas reduced from the first year to the final one for both inside and adjacent of exclosures.however, the cover of (class iii) species in the final year was not significantly increased thanthat for the first year. forage production generally was higher inside than adjacent ofexclosures. litter increased during the study period for both inside and adjacent. litter wassignificantly higher inside of exclosures than adjacent in 2005. although the plant canopycover was affected by rainfall but correlation coefficient was statistically significant only fortotal, annual and some perennial canopy cover species. although total and annual cover washigh inside and adjacent of exclosures in 2005, the cover of perennials was decreased. by thereduction of palatable species, unpalatable species were increased inside and adjacent.although by increasing the plant cover, the range condition was relatively improved, thisimprovement was achieved by the increase in the annuals instead of perennials. it wasconcluded that the exclosure cannot be used as a range improvement method to improve theserangelands’ conditions. for the rehabilitation of these areas, human interference is necessary.