كليدواژه :
تجزيه مؤلفه هاي اصلي , واحد اكولوژيك , آناليز گونه هاي شاخص دو طرفه , تحليل خوشه اي
چكيده لاتين :
The objective of this study is investigation of environment-vegetation relationships and determination the most important environmental factors affected distribution of vegetation types in Darab rangeland, Fars province. In the study area 18 vegetation type was identified and sampling of vegetation was performed using randomized-systematic method. Soil samples were taken at 0-30 cm and 30-60 cm depths in each plot. Soil characteristics including texture, lime, electrical conductivity, saturation moisture, gypsum, sodium absorption ratio, acidity, cation exchangeable capacity, organic materials and soluble ions were measured and annual mean temperature, annual mean precipitation and elevation were determined. Direct and indirect ordination techniques as principle component analysis (PCA) and canonical correspondence analysis (CCA) was used to examine the relationships between the vegetation and environmental variables. Analysis with PCA gave results similar to CCA, suggesting that there is a relatively high correspondence between vegetation and environmental variables. Results showed that precipitation, soluble ions, texture, EC, gypsum and organic materials, explaining 87.5 percent of total variance, affected distribution of vegetation types. Classification of vegetation is analyzed using two-way indicator species analysis (TWINSPAN) and cluster analysis techniques and three ecological units were recognized. The results of this research can be used in similar regions and useful to design natural resources management projects.
