Assessing the Effects of Native Plants to Slope Stabilization in Road Embankments: A Case Study in Siyahkal Forest, Northern Iran

Soil bioengineering is the low-cost way for slope stabilization in forest roads. Considering economic efficiency, the focus of the present study was to reduce environmentally destructive effects of roads by finding out the appropriate native plants for bio stabilizing slopes and also aiming at providing soil bioengineering decision making skills. The research was carried out through 30 systematic randomly distributed plots at two slope classes. In each sample plot, geological features (slope steepness, aspect and altitude) and various plant species were recorded. Three extra sample plots were taken in upland slopes to illustrate the success and failure of vegetation’s presence. Geographical plan showed that roads were located at three land types where total existing land types were five. In total, five cores with 30 cm in diameter and 60 cm in depth created for laboratory tests of soil mechanical characteristics (liquid limit, solid limit and texture). Results revealed that there is a relation between plant species and variables such as land type, soil moisture, soil texture, aspect, slope, and soil depth of study area. The dominant tree species in the study area were Carpinus betulus with 24.5% followed by Parrotia persica with 17.3% which was followed by Quercus castanefolia (11.7 %), Fagus orientalis (8.2%), and Alnus subcordata (7.9%). Land type (A) is suitable for road structure, (B) is not suitable for road structure and (C) is relatively suitable for road structure.