Changes of plant biodiversity indices in ecological species groups along an altitudinal gradient

In this paper we described variations of plant biodiversity indices in the plant communities of Salaheddinkola forests, Nowshahr. For this purpose, plant species floristically data with some environmental properties have been recorded in 76 plots (400 m2) along two altitudinal gradients (200–2300 m a.s.l.). Five ecological species groups were distinguished by using the results of TWINSPAN which were done based on floristic cover data. The comparison of diversity indices between ecological groups were done by ANOVA test and DCA Analysis. Results showed that biodiversity indices had significant differences between plant communities. The plant communities I and II, which represents Carpinus betulus-Parrotia persica forests and located in lower elevations had the largest values of Simpson’s Diversiry index, shannon’s Diversiry index and Shannon Evenness index. As well as, Simpson Dominance was maximum in the III, IV and V plant communities, which represents the beech forests at the higher altitudinal ranges. Result also showed that there was no clear trend in Richness index’s along the altitudinal gradient. Finally, we concluded that altitude was a basic factor in variations of plant biodiversity indices and distribution of plant communities in this area.