Investigating the plant species composition and diversity in altitude gradient of Alvars-Sabalan summit

Research Aim: The aim of this study was to investigate the composition and diversity of plant species in elevation profiles of 2300 to 4811 m above sea level in Alvaras village rangelands to Sabalan peak in southeastern Sabalan mountain. Research method: After field surveys and considering the availability of access to rangelands in the area, 9 elevations were identified, each site 3 transects per 100 m and 10 plots a square meter in per 10 m in each transect. Plant species were collected from the plots and then identified. In each plot, vegetation percentage and species density were recorded. Three soil samples were taken from each transect at a depth of 30 cm and then combined and a homogeneous soil sample was obtained. totally, 27 soil samples were obtained from 9 sampling sites. Some soil parameters such as texture, organic carbon, acidity, electrical conductivity, moisture content, lime, potassium, sodium, phosphorus, magnesium, calcium and nitrogen were measured. PASTver5 software was used to study the diversity and richness of plant species using Shannon, Simpson, Margaleph and Mannheim indices. One-way analysis of variance (ANOVA) was performed with SPSSver24 software and vegetation classification analysis including CCA in CANOCOver4.5 and PC-ORDver5 software. Findings: Asteraceae family with 31 species, Astragalus genus with 10 species, Hemicryptophytes with 85 species are the most prominent elements of flora in the region and 51 species belong to Iran-Turanian area. The highest diversity, richness and evenness were observed in the altitude of 2200-3200 m. CCA showed that altitude, precipitation, temperature, soil sand content, slope and phosphorus were factors affecting plant distribution. Conclusion: In the study of the effect of altitude on plant composition and diversity, it can be deduced that altitude is influenced on plant composition and diversity, and in general it can be said that species composition and diversity status in southeastern Sabalan rangelands is based on diversity and evenness indices. It is being degraded.