Changes in vegetation cover of Sirachal mountain rangelands due to fire

Fire in rangelands has significant effects on plant and soil factors. In this research, the effects of fire on plant factors were investigated in semi-steppe rangelands of Sirachal for three years (2015-2017). The two selected rangelands were similar in terms of vegetation type (before the fire) were next to each other. The treatments included control rangelands and burned rangelands, and sampling was performed using transects and quadrates (30 plots) for three consecutive years. Vegetation factors included canopy cover, production, density, species richness, and life form. The statistical analysis of the treatments was carried out using the independent t-test. Comparison of different years, in each of the burned or control rangelands, was done using analysis of variance and the means were compared with Duncan's test. The results showed that fire during the years of the project did not have a significant effect on the canopy percentage and the production of all rangeland species, but it had a positive and significant effect on the density of all rangeland species. High difference in density compared to the cover and production could be due to the low canopy cover and production of new seedlings. In other words, new seedlings of plants had a low canopy cover, low production, and a high density. In terms of species richness, the highest difference is related to the absence of shrub species in the burned rangeland; however, according to the Sorenson index, the two treatments were similar in terms of plant species. Also, in terms of life form, fire had a positive and significant effect on the cover percentage, density and production of forbs, a positive and significant effect on the cover percentage and density of grasses, and a significant negative effect on the shrubs.