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Unstable slopes create numerous problems for forest management and may destroy the road network and disturb access to forest. Soil bioengineering is a solution that can prevent these problems and reinforce the hillslope. Persian ironwood is considered as a good protective species for hillslope stability in Iran with an extensive lack of information about biotechnical properties. In this research the root strength of this species and also the relation between root diameter and cellulose content were investigated. The results showed that the mean tensile force and tensile strength were 99.70 ± 2.01 N and 173.23 ± 4.94 MPa, respectively, for the root diameter range between 0.22 and 3.78 mm. The results of ANOVA showed that the power models between root diameter and tensile force and tensile strength were statistically significant and the results of t-test showed that coefficients and constants of the models are also significant. The values of the parameters of the power law (α and β) obtained for Persian ironwood do not fall in the range that has already been suggested for hardwood roots, which may be due to a narrow diameter range. The mean cellulose content was 56.87 ± 5.79% and the relationship between root diameter and cellulose content was not statistically significant. The data presented in this study expand the knowledge of biotechnical properties of Persian ironwood and support the idea that there is still an extensive lack of information about plant roots as a bioengineering material.

GPS receivers are frequently used for engineering activities in forests; however, a number of factors, including natural barriers (mountain and tree canopy) in the forested areas, affect their accuracy. The aim of this study was to evaluate the accuracy and precision of a consumer-grade GPS (Colorado 300) receiver in road mapping. For this purpose, a length of 12.2 km of main forest road was selected in the Hyrcanian forest, northern Iran, and a ground truth map was extracted from the National Cartographic Center maps. The forest road was mapped in four seasons for three days to evaluate the seasons’ effects on the location accuracy and five- and ten-meter buffers were used for the same purpose. The results of two-way ANOVA showed that there were significant differences in the precision and accuracy of the GPS receiver due to the season. The best and worst mean accuracy and precision were in spring (24.45 m and 24.97 m) and autumn (56.10 m and 53.65 m), respectively. The findings showed a positive effect of averaging (5-61% improvement in relation to season) on the position accuracy. Also, ANOVA did not show any significant differences between the overlay lengths due to season in both the five-and ten-meter buffers. It can be concluded that consumer-grade GPS receivers could meet forestry needs. The averaged accuracies in spring are acceptable for many forestry applications and satisfy the mapping requirements.

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