Root strength changes after logging in southeast Alaska

Abstract

Abstract - A crucial factor in the stability of steep forested slopes is the role of plant roots in maintaining the shear strength of soil mantles. Roots add strength to the soil by vertically anchoring through the soil mass into failures in the bedrock and by laterally tying the slope together across zones of weakness or instability. Once the covering vegetation is removed, these roots deteriorate and much of the soil strength is lost. Measurements of change in strength of roots remaining in the soil after logging at Staney Creek on Prince of Wales Island, south-east Alaska, indicate that loss of strength in smaller roots occurs rapidly for all species the first 2 years. Western hemlock (Tsuga heterophylla (Raf.) Sarg.) roots are more resistant to loss of strength than are Sitka spruce (Picea sitchensis (Bong.) Carr.) roots. By 10 years, even the largest roots have lost appreciable strength.

Citation

Ziemer, R. R.; Swanston, D. N. 1977. Root strength changes after logging in southeast Alaska. U.S. Dept. Agric., Forest Service, Research Note PNW-306, Portland, Oregon. 10 p.