Investigation of the effects of roads on the Persian oak forest ecosystems from the point view of the understory plant communities diversity and physico - chemical properties of soil

Road construction in forest ecosystem makes changes in vegetation composition, biodiversity and soil characteristics. To investigate changes in plant communities due to road construction in Zagros forest ecosystem, two-kilometer of roads which is located in coppice and coppice with standard stand (in Bakool region, Lorestan province) was selected. Twelve transects were selected at different intervals of the road axis.To collect of plant and soil samles, in intervals of 20, 50, and 100 meters from the road edge 72 plot 20×20 meter  were selected On each one of transects. Relationship of vegetation and soil properties investigated by using of the canonical-correlation analysis (CCA) and for grouping of plant species two- way indicator species (TWINSPAN) analysis used. Biodiversity was estimated by using the Simpson and Shannon – wiener diversity indices, Margalef and Menhinic indices and the Pilo index. Results showed that the species composition of sections close to the road was different from the sections inside the forest and they were classified in two separate groups. Also results showed that the greatest amount of organic carbon, lime, saturation, absorbable potassium were seen at distance of 100 m in coppice and seed stand and also the greatest amount of absorbable phosphorous was seen at distance of 50 and 100 m in this stand. Also the greatest amount of salinity, total nitrogen and bulk density were seen at distance of 20 and 50 m in coppice seed stand. Acording to the results biodiversity indices showed that the greatest amount at distance of 100 m in both stands. The results of this study showed the negative impacts of road construction on the vegetation composition and physic-chemical properties of soil in this forest.