Evaluation of herbaceous species diversity in not harvested beech forest, case study: Roudbar of Guilan

The aim of this study was to evaluate herbaceous species diversity in a pure and an untouched beech forest. For this purpose, 170 ha of Roudbar forest of Guilan province were investigated. With using biological indices, numerical values of species diversity, richness and evenness calculated and the results were compared to similar studies. Results showed that values of indices obtained are less than other studies. Causes of this problem are a lot of litter depth, high canopy percentage, being the study area at high altitudes and the lack utilizing in the region due to lack of road networks. The evenness amount had more effective than richness in diversity amount. Abundance distribution curve of species followed log normal model.The most cover percentage was related to Bromus benekenii species that is an exotic species and is considered a serious threat to biodiversity in the region.