Diversity of Herbaceous and Woody Plant Species in Relation to Different Physiographic Conditions using Numerical and Parametrical Indices in Zagros Mountainous Forests

Numerical and parametrical indices are two of the most important and most widely used indices for assessing biodiversity in different societies. Nevertheless, their efficiency and selection in various ecosystems has always been one of the challenging issues of ecology. In this study, the numerical indices of diversity, richness and eveness, as well as abundance–ranking distribution models including broken stick, log normal, log series and geometric series as parametrical indices of diversity were calculated seperatly for herbaceous and woody species in different physiogrphic conditions in zagros forest ecosystem. Results showed that there was significant different between various physiographic conditions in term of numerical indices as the Shannon-Wiener diversity and Margalef richness indices of herbaceous species in the northern aspect have a similar trend and the highest values ​​of these indices were on slope of 0-25% and their values decreased with increasing slope. In contrast, the diversity and richness of woody species was higher in south aspect and slope more than 50%. The results showed that, in all physiographic situations, the frequency distribution of herbaceous species is more consistent with the geometric series model which indicates low biodiversity and fragile communities. In the case of the woody species frequency distribution, results showed that the log series and broken stick were the best models on north and south-facing slopes respectively.