20 Oct 2025

Tensile Strength of Native Boreal Forest Plant Species

Abstract: Plant roots influence the engineering properties of soil, such as erodibility and strength. Plant roots’ contribution to soil shear strength is of particular importance in Arctic and subarctic environments where the shallow subsurface experiences a decrease in shear strength due to permafrost thaw, subsidence, and wildfires. This paper presents the testing method, sample collection and specimen preparation, and tensile strength testing results for laboratory- and greenhouse-grown boreal forest plants to compare root tensile strengths among plant species and functional groups, including deciduous shrubs and trees, evergreen trees, forbs, graminoids, and grasses using a universal testing machine and a modified triaxial device. The results illustrate that root tensile strength increases as root diameter decreases (as a power function). The root diameters successfully tested ranged from 0.063 mm (grasses) to 8.72 mm (deciduous shrubs) across all functional groups. When compared across functional groups and root diameters for each species, grass roots exhibited the highest tensile strength for root diameters less than 0.8 mm, deciduous tree roots displayed the largest tensile strength for root diameters greater than 0.8 mm, and forbs were consistently the weakest, supporting the conclusion that a diverse spread of functional groups is most effective for slope stabilization.

2 Jul 2025

Remote Detection of Soil Shear Strength in Arctic and Subarctic Environments

Abstract: Soil shear strength affects many military activities and is affected significantly by plant roots. Unfortunately, root contribution to soil shear strength is difficult to measure and predict. In the boreal forest ecosystem, soil and hydrologic dynamics make soil shear strength less predictable, while the need for prediction grows due to the rapid changes occurring in this environment. Our current study objectives are to (1) observe possible aboveground vegetation indicators of soil shear strength variation across soils and other environmental heterogeneity, (2) observe possible image-based indicators of soil shear strength variation, and (3) identify the best remote-sensing data source for predicting soil shear strength variation. A total of 65 sites were sampled from a diversity of soil and vegetation types across interior Alaska and Ontario, Canada. Ground-collected data were analyzed to develop a predictive model, while a similar approach was undertaken with Sentinel-2 imagery. Results indicate that both ground-collected data and satellite imagery can reasonably predict boreal forest soil shear strength, with satellite imagery providing the higher predictive ability. A comparison of 10 m Sentinel-2 and submeter Maxar imagery indicated that Sentinel-2 provides a better prediction of soil shear strength.