The study looked at different ways to measure plant diversity in mountain rangelands. They found that using both numerical and parametrical indices is better than just using one. They calculated species richness, evenness, and diversity for four plant communities in Iran. The results showed that all communities had high diversity, making it hard to pick the one with the most species. They also found that plant diversity is highest with moderate grazing levels. The log-normal model was the best at predicting species distribution in these areas. This supports the idea that moderate disturbance levels lead to more plant diversity.