Identification of relationship between some physiographic attributes and physico-chemical soil properties and ecological groups in Melehgavan protected area, Ilam

This study was carried out in Melehgavan protected area (app.160 ha) located in northwestern of Ilam city. The main objective of the study was to survey the ecological species groups in relation to some physiographic attributes and soil physico-chemical properties. The field data were obtained using 67 sample plots (20m×20m) in a systematic random grid. The attributes including tree and shrub species type, number of each species and canopy coverage, which were recorded by measuring their small / large crown diameters in each sample plot. In order to record the herbaceous species, the Whitaker’s snail plot method was applied, which resulted in 81 m2 of the minimum plot area. The Canonical Correspondence Analysis (CCA), Principal Components Analysis (PCA) and TWINSPAN methods were used for the site classification, determining of the relationship between species composition and environmental properties and also definition of ecological species groups, respectively. Results indicated that there were three ecological species groups in the study area. The first group had a positive correlation with the soil pH. There was no indicator tree species in this group but Stipa capensis, Fibigia macrocarpa and Medicago rigidula could be detected as indicator herbaceous species. The second group was established in the higher elevation and its site had more moisture and mineral nutrients than the sites of other groups in the area. Quercus brantii and Bromus tectorum were identified as the indicator species for this group. Daphne mucronata and Euphorbia macroclada species were defined as the indicator species for the third group, which was established in the low elevation above sea level. The mineral nutrients of this group were less than the second group.