Effect of the mountain pine beetle on slope stability, soil moisture and root strength, The

Abstract

The mountain pine beetle (MPB) has caused significant tree mortality within North America. This work explores the impact of such unprecedented tree mortality on slope stability. Within the first growing season following infestation, transpiration ceases; thus saturation increases, adding a driving force to slope failure. The increase in saturation was the primary driver for the decrease in the Factor of Safety. The hydrologic properties were modeled using ParFlow. As the trees and roots decay, the root tensile strength decreases by 0.2μPa within the first few years of mortality. The combination of the decrease in root tensile strength and the increase in saturation were used to assess the impact of MPB mortality on slope stability through examining changes in the Factor of Safety using an infinite slope model. From a sensitivity analysis, the largest change in the Factor of Safety (a decrease of 5%) was observed at the lowest angled hillslopes.