Effects of roads on understory plant communities in a broadleaved forest in Hyrcanian zone

This study was conducted to assess the effect of forest road as a corridor on local biodiversity. For this purpose, 10 segments in a 10 year-old road were selected in Neka-Zalemrood forest in Hyrcanian zone. At each of the segments, we established two 100-m transects perpendicular to the road centre line, within which we sampled three macroplots of an area 400 m2. In each macroplot, nine quadrant microplots 2 × 2 m in size were set up for regenerated tree species and herbaceous plant survey. Chemical and physical parameters of soil were measured in laboratory. Results indicated that thirty-six herbaceous species and 13 regenerated tree species were recorded within the area of 100 m from the road verge. At the different distances from the road verge and both down and up-slope, the ground cover of Carex sylvatica and Rubus caesius L. as well as regeneration density of Carpinus betulus L. were higher compared to other species. Menhenick, Margalef, Shannon and Simpson indices were higher at the distance of 0-20 m than at the distances of 40-60 m and 80-100 m. Camargo and Smith-Wilson indices decreased when increasing distance to the road. These results are expected to provide critical information for decision makers and land managers for managing plant species and maintaining the integrity of biological communities.