Document Type : Research Paper
Department of Arid and Mountainous Regions Reclamation, Faculty of Natural Resources, University of Tehran, Karaj, Alborz, Iran
Species diversity is a combination of species richness with species evenness. It helps us differentiate between communities or areas that have the same number of different species, but not in the same abundance. The spatial distribution pattern of plant species is an important topic in plant ecology, the assessment of which is an essential part of research into plant communities. This study aimed to investigate the differences between richness, diversity, and evenness indices obtained for random, uniform, and clumped distribution patterns. For this investigation, three plant distribution patterns were simulated and then random sampling was performed with 10 plots of the size 1 m2 for each pattern, each with five repeats for greater accuracy. Finally, the number of species, the Margalef index, and the Menhinick index for richness, the Simpson index and the Shannon-Wiener index for diversity, and the Simpson index, the Shannon-Wiener index, and the Pielou index for evenness were computed and compared. The results of the analysis of variance showed a significant difference between richness, diversity, and evenness indices in different distribution patterns. Accordingly, Shannon-Wiener diversity is the best index when the management objective is more concerned with rare species. Also, Simpson’s diversity, would be more appropriate where dominant species are more important.