Comparison of plant species diversity in two rangelands under grazing and exclosure conditions, Lorestan province (Case Study: Northeast Delfan County)

This research was aimed to investigate the effects of exclosure on species diversity changes under grazing and exclosure conditions in the northeast rangelands of Delfan County, Lorestan province. For this purpose, 120 quadrates of 1*1 m2 were established in a randomized-systematic method along 12 transects of 100 m length at four altitude classes (three transects on each altitude class). In each quadrate, the list of species, density, the percentage of canopy cover, litter, stone and gravel, and bare soil were recorded. To evaluate the numerical indices of diversity, Ecological Methodology software (Ver., 6.2) was used and numerical indices of diversity and evenness were calculated. Data analysis was performed in SPSS software (Ver. 18). According to the obtained results, a number of 132 species were identified, belonging to 30 families and 104 genera, of which 124 and 108 species were recorded in the rangelands under exclosure and grazing conditions, respectively. Our results clearly showed higher numerical indices for richness, evenness, and species diversity under exclosure as compared with grazing condition. The canopy cover percentage of perennial grasses and forbs as well as litter percentage was higher inside the exclosure while the canopy cover percentage of annual grasses and shrubs as well as bare soil percentage was lower as compared with outside the exclosure. The density of perennial grasses and forbs increased, while the density of shrubs decreased inside the exclosure. In addition, a higher production was obtained from the rangeland under exclosure condition.