Biodiversity of forest and steppe associations in Juniper(Juniperus excelsa) habitat of southern Alborz (Firuzkooh, Iran)

In Management of natural resources and prioritization for conservation, a strong scientific foundation of biodiversity data is needed. Despite the importance of forest habitats of Irano-Turanian region, they have been less studied in term of biodiversity. This study focused on plant diversity in some parts of these habitats. Study area included five stands in southern Alborz mountain. Sampling was carried out by plots along the transect lines taking place at regular intervals within each habitat. Plot size was determined by the concept of minimal area. Biodiversity was investigated using Simpson, Shannon-Wiener, Margalef, Menhinick, Sheldon and Pielou indexes. One way ANOVA following by Dunkan multiple range tests were used to analyze the indexes in relation to associations and environmental variables. According to the results, diversity in forest associations was significantly more than steppe associations. Similarly, the difference was seen at the family level. The greatest amount of diversity belonged to Amygdalo lycioidis-Pistacietum atlanticae and Lonicero ibericae-Juniperetum excelsae and the least amount belonged to Feruletum ovinae. Diversity indexes in Artemisio aucheri-Astragaletum veri were significantly more than Artemisio aucheri-Onobrychidetum cornutae. Among the environmental variables, slope, aspect, soil organic matter and soil texture were significantly associated with the diversity indexes; with the increasing in the slope up to 80%, plant diversity and species richness increased, then significantly reduced. In terms of soil texture, the highest diversity and species richness observed in sandy clay and sandy loam soils. As well as, soils with organic matters more than 6%, were richer in terms of plant diversity.