اثر قرق کوتاه مدت بر تولید چمنزارهای کوهستانی در منطقه زاگرس مرکزی

Major changes in the vegetation and consequently in the ecosystem functioning of mountainous meadows has been reported in response to herbivore grazing. Nevertheless, effects of protection from herbivores on the vegetation of High-elevation meadows in Iran have not been studied so far. To assess effects of experimentally short-term exclosure treatment on production of mountainous meadows, two meadow sites were selected in Sabzkouh Protected Area in Chaharmahal and Bakhtiari Province. In each site, three 16 m2 (2×8 m) fences were established and in each fence three 1 m2 plots were marked at the beginning of the growing season (April). Similarly, three 1 m2 plots were placed outside each fence (resulting in 18 grazed and 18 protected plots). In the second year at peak vegetation growth and shortly before grazing season (July), above-ground biomass was cut in all plots and then dry weights of vegetative and reproductive organs were determined separately. Grazing exclusion significantly increased total biomass, while it decreased the proportion of reproductive biomass in meadow vegetation community. Protection from grazing increased biomass production of dominant and tall plant species (e.g., Carex orbicularis), but had reverse effects on smaller and less frequent species. Nevertheless, grazing exclusion decreased the proportion of reproductive biomass in all meadow species (except for C. orbicularis) and various species groups (except for grass-like species). The results of the present study may thus be used for objective-oriented management and conservation of high-elevation and mountainous meadow ecosystems of the country