Evaluating the plant diversity of understory of oak forests in relation to some of ecological factors (case study: Ilam province)

Diversity is an important indicator to assess the condition of ecosystems. Reduction of diversity leads to reduction in the environmental capacity. To this research, some ecological factors such as altitude, slope and aspect in this were determinal. Then, using 480 plots of one meter square (1m2), was done with random – systematic sampling method to measuring the plant species factors. To determine species richness indices of Margalef and Menhinic, for the diversity, indexes of Shanvnvaynr, Simpson, and to calculate evenness, indexes of Simpson and Paylo were used. The results showed that ecological factors have significant influence on the species richness, diversity and evenness, (P