Response of vegetation composition and diversity to degradation to soil physical, chemical and biological properties, Zagros forest ecosystems

The current research was performed in two regions of control and degraded areas in Ivan County in Ilam province. In both regions, a number of four areas were selected randomly according to the indicator standing concept. In each area, 16 circle plots with an area of 1000 m2 were sampled for sampling shrub and tree species. Two micro-plots (1m2) were sampled for sampling herbaceous species in each main plot. As well, soil was sampled in three locations per plots (0-20 cm depth) which a combined sample was analyzed for finding soil chemical, physical and biological characteristics. The analyses of DCA and PCA methods were shown that the sample plots were separated according to species composition and environmental variables. The results of soil characteristics and diversity indices based on the main attributes indicated that high amount of species richness, soil nutrient and soil biological activities were found in the control region. Otherwise, species evenness, percentage of soil sand, lime, and salinity were highest in the degraded area.