Relationship between Plant Ecological Groups

In a natural ecosystem, vegetation elements of similar ecological needs constitute ecological groups. In fact, through distinguishing different ecological groups, the differences among environmental variables in various sites can be realized. The aim of this research, done in University of Tehran ’s educational – research forest located in Kheiroudkenar forest – Noshahr, was to explore ecological groups and their relationship with soil characteristics. In order to determine plot (releve) area, minimal area method was employed. To study vegetation cover, 151 plots of 400 m2 area were collected according to Braun- Blanquet combinational method. Following data collection, plant community was separated and classified using Two Way Indicator Species Analysis (TWINSPAN), differential species being indicated in each group. Based on ecological groups and the presence of differential species, 36 points were assigned to introduce physical and chemical characteristics of soil, and the resulting sample were analyzed. In order to analyze soil characteristics in relation to vegetation cover changes, multi – variable analysis, e.g. principal components analysis (PCA) was exploited. The results illustrated that the first ecological group, namely Ruscus hyrcanus, and second group including Asperula odorata, Viola odorata, Hypericum androsaemum, Dryoptris filix-mass, were related to soil chemical properties. The third group with Oplismenus undulatifolia, Cyclamen caucasicum, along with the fourth group, including Mespilus germanica, Rumex sanguineus, Solanum kisereitzcki were mainly in relation to physical properties. Also, it was found that soil fertility in the first and second groups is more suitable and higher than in the others.