Document Type : Scientific article
Authors
1
M.Sc. of Forestry, Faculty of Natural Resources, University of Tehran, Karaj, I.R. Iran.
2
Associate Professor, Department of Forestry and Forest Economics, Faculty of Natural Resources, University of Tehran, Karaj, I.R. Iran.
3
Professor, Department of Range and Watershed Management, Faculty of Natural Resources, University of Tehran, Karaj, I.R. Iran.
4
Professor, Department of Forestry and Forest Economics, Faculty of Natural Resources, University of Tehran, Karaj, I.R. Iran.
Abstract
In this research two forest plantations (Picea abies and Fraxinus excelsior) with similar site conditions were selected in the near vicinity of each other. Three trees of each species were randomly selected for later analysis. Profile trenching method was then used to analyze and compare their root distribution. Root samples of each species were collected to test their tensile strength using a standard Instron. The results showed that, RAR values and additional root cohesion tend to decrease with soil depth following a logarithmic function for both forest species. Also for both studied species, root tensile strength tend to decrease with increasing root diameter following a power function. According to the results, over 80 percent of roots were found to be within the top 20 cm of soil profile, indicating the highest reinforcing contribution within this layer. The results revealed that the root tensile strength of Picea abies (19.31 ± 2.64 MPa) with roots diameter ranging from 0.32 to 4.93 mm were greater than that of Fraxinus excelsior (16.98 ± 1.01 MPa) with roots diameter ranging from 0.42 to 4.91. Also, the additional root cohesion from Picea abies (0.03 ± 0.008 kPa) was found to be significantly greater than that from Fraxinus excelsior (0.02 ± 0.005 kPa). The results of this work may help us when applying an efficient bioengineering technique.
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