www.scholarsresearchlibrary.com t Available online a Scholars Research Library Annals of Biological Research, 2012, 3 (11):5019-5027 (http://scholarsresearchlibrary.com/archive.html) ISSN 0976-1233 CODEN (USA): ABRNBW 5019 Scholars Research Library Study of Plant Biodiversity in Grazed and Non-grazed Areas in the Iran-o-Turanian Ecological Zones (Case Study: Yazd Province, IRAN) Maziar Haidari 1* , Hamid Jalilvand 2 , Reza Hossaein Haidari 3 , Naghi Shabanian 4 1* Young Researchers Club, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran 2 Department of Forestry, Sari University of Agricultural Sciences and Natural Resources, sari, Iran, 3 Department of Forestry, University of Razi, Kermanshah, Iran 4 Department of Forestry, University of Kurdistan, Sanandaj, Iran. ____________________________________________________________________________________ ABSTRACT Species diversity is one of the most important indices was used to evaluate the sustainability of forest communities. In this study, the effect of complete protection (non-grazed) on plant species diversity was investigated in Bagh-e- Shadi Forest (Irano-Turanian Forest), Yazd province, central of Iran. For this purpose, sampling designed the randomized-systematic method with rectangular plots that were 40×50 meters in the 100×200 Net, Shrub species in the 100 square (10×10 meter) and Herb species in the 25m 2 (5×5 meter) were sampled in the center of net inventory. In the total 60 sample plots (30 plots in the grazed and 30 plots in the non-grazed area) were sampled. In every sample plot recorded plant species and number of this plant. In order to analyze biodiversity indicators of Shannon-Wiener and Simpson as well as Margaleff evenness indices was applied. Results indicated that Gramineae, Compositae, Labiatae, Rosacae and Anacariaceae families have the highest number of species. Pistacia atlantica and Amygdalus communis were the most dominant woody plants for class of tree and Acantholimon sp. and Astragalus spp were the most dominant Shrub plants, respectively. Bromus tectorum and poa sinacia were dominant herbaceous species. Herbaceous layer had the highest richness, evenness and diversity. The differences between biodiversity indexes in the two areas were statistically significant in the tree, shrub and herbaceous layer. So the grazed and non-grazed increase tree, shrub and herbaceous diversity in Irano-Turanian forest, and complete protection (non-grazed) area have higher plant diversity compered the grazed region. Therefore, prevention of livestock grazing and irregular tree cutting in the degraded forest stands can be suggested as a suitable approach for natural restoration and increasing plant diversity. Key words: Iran, Yazd Province, Tree, Bush, herbaceous, Vegetation Layer. ___________________________________________________________________________________________ INTRODUCTION I.R. of Iran is located in the North Temperate Zone from 25 to 40 latitude and 44 to 63 longitude degrees, with a total area approximately 1,650,000 Km2. A large section of interior is characterized by arid basins. Climatic variations are also great in Iran. The main variation is between the dry, desert interior region and humid Caspian coastal region (24). With due to attention to climatic conditions of Iran, 65% area includes arid and semi-aireid and degradation rapid of north and west, because of degradation of natural resources will cause to degradation agricultural lands and human environmental (6). Forests cover about 12 million ha in Iran (Forest and Rangeland Organization 2002), The Irano-Turanian region covers an area of about 3,452,775 ha with dry and mainly cold climate in winter. They are situated in Khorasan, Azarbaijan, Markazi and westem Provinces. Regarding to topographical conditions and diversity of species, the region is divided into plain and mountainous sub - regions. Plain sub – regions located in the less 2000 meter a.s.l and main tree is Pistacia Forests. Pistacia Forests include