The use of modern methods in the analysis of rangeland ecosystems has received much consideration. The study of the diversity of medicinal and sometimes toxic species in rangelands can be regarded as an indicator of ecological status changes in rangeland ecosystems. In the present study, Javaherdeh mountain rangelands in north of Iran were selected under three sites including long-term exclusion, medium-term exclusion, and grazing during 2018-2019. Sampling was performed in each plant type with 4 transects of 200 meters and a random point every 10 m. Identification of species was carried out using published methods. Shannon’sdiversity,Margalef’srichness, dominance, and evenness indices were determined for each plot. The means comparisons were made for the three study sites using one-way ANOVA in SPSS v.22 software. According to the results, the highest values of diversity and richness indices for medicinal plants (1.817, 2.370) and total plants (2.062, 3.132) were calculated for the long-term exclosure. The evenness index for total species in the medium-term exclosure (0.588) and grazing area (0.620) was almost similar and higher than the amount of the long-term exclosure (0.058). However, the mentioned index for medicinal species in long term exclosure (0.739) was higher than two other sites. The dominance index for total plants in the grazing area (0.260) was higher than two other sites; however, this index of medicinal plants was higher in the grazing (0.355) and medium-term exclosure (0.393) sites as compared with the long-term exclosure (0.224). Overall, species diversity indices of medicinal plants could be a proper tool to interpret the ecological changes in range conditions. Therefore, ecological management of rangelands could be achieved through understanding and knowledge of these changes. تفاصيل المقالة