Analysis of the relationship between rangeland vegetation types and environmental gradient using multivariate methods in western Taftan, southeastern Iran

determine the relationships between distribution of vegetation types and environmental variables in rangelands of western Taftan, southeastern Iran. At each key area, vegetation sampling was carried out by randomized-systematic method along four sampling lines with 150- 200 m length. Quadrat size was determined by minimal area method with regard to the type of plant species which ranged from 2 to 25 m2. Sample size was determined 45-60 samples using statistical method by taking into account variation of vegetation. At each vegetation type, soils were sampled in 0-30 and 30-80 cm depths within eight soil profiles. Soil properties including gravel percent, texture, saturation moisture, available water, lime, gypsum, organic matter, acidity (pH), electrical conductivity (EC) were measured by standard methods. Classification of vegetation using TWINSPAN in the study area generated five vegetation types with different ecological requirement. Analysis of the relationship between vegetation types and environmental gradient using principal component analysis showed that distribution of different vegetation types was mainly associated with environmental variables. Altitude, slope, gravel percent, geological formation, percentage of lime, and soil texture were the most important environmental variables, determining separation of plant communities in the studied rangeland. Knowledge on the effective environmental variables on plant species distribution can make possible the selection of plant species by range managers on the basis of their ecological requirements in range improvement and development programs. This important issue not only will increase success of vegetation management plant but also it will decrease management cost.