In this study, the impact of land use change of forest areas to forest parks on species diversity indices in Chaghasabz Park (Ilam city) has been investigated. For this purpose, three regions in 30-hectare areas were considered, including the area, without, medium and intensive recreation. The field data were obtained using 20 sample plots with each plot covering an area of 400 m2 in a systematic random design (150 m×100 m) in each region. In order to record the herbaceous species, cover percentage for each herbaceous species was recorded in four micro-plots (1.5 m× 1.5 m) that were defined with Domin criterion. In order to evaluate plant diversity, biodiversity indices e.g. Shannon and Simpson and Maguran richness indices were computed. Also, for studying the comparison between the averages of plant diversity indices, Dunken analysis was used. The results showed that in areas without, average and intensive recreation, there were 29, 45 and 21 species respectively. Therophytes were dominant vegetative forms in all three areas. Asperula odorata, Centaurea irritans Wagentz. Marrabium vulgare L., Phlomis olivieri Benth. and Picnomon acarna (L.) Cass were not observed in intensive recreation region. The least shannon and Simpson diversity and richness indices were observed in intensive recreation region, but on the contrary, evenness index was substantial in intensive recreation. We concluded that intense increase of recreation in forest region might cause a loss species diversity.
