investigation of biotechnical properties of parottia persica in order to use in bioengineering (case study: patom district of kheyrud forest)

vegetation is known to increase hillslope stability by reinforcing soil shear resistance. this reinforcement depends on the density and tensile strength of the root systems. this paper presents the results of research carried out in order to evaluate the biotechnical characteristics of the root system of parrotia persica. the profile trenching methods was used to obtaining root area ratio (rar) and number of roots in each depth and rar and numbers were counted. single root specimens were sampled and tested for tensile strength measurement. the findings indicated that the general behavior of root density and number of roots is to decrease with depth. maximum rar values and number of roots were located within the first 0.1 m, with maximum rooting depth at about 0.60 m. in general root tensile strength tends to decrease with diameter according to a power law, with an average of 29.34±1.5 mpa. the resulting data have been used to calculate the reinforcing effect in terms of increased shear strength of the soil. the results show that root reinforcement exerted by parrotia persica is about 44.90 kpa in upper layers and 1.65 kpa in deeper horizons. the results presented in this paper can be used in practical bioengineering.