Clearcut logging is negatively affecting our drinking water
Landslide into Harmony Creek directly off freshly cut logging road on steep slope, Coquitlam watershed, April 1990.
Clearcut with associated landslide, Eastcap Creek, Capilano watershed, Dec. 1988.
Experts warn of damage
"The combined impact of roads and clear-cut logging has constituted a fivefold increase in landslide erosion relative to undisturbed forested areas."
-F. J. Swanson, C.T. Dyrness, Impact of clear-cutting and road construction on soil erosion by landslides in the western Cascade Range, Oregon.
"Even a 'full benched' road inevitably upsets the balance of forces within the soil mantle. A decision to build a road in an area of unstable topography constitutes a calculated risk no matter how well the road is designed and constructed to minimize damage."-R.L. Fredriksen, A Case History of a Mud and Rock Slide on an Experimental Watershed
"In an area of southeastern Alaska, a drastic change in landslide pattern occurred after logging. In a period of 100 years before logging, 27.3 acres were affected, but in a period of only ten years after logging, 119 acres were affected, a 43-fold increase in area."
-Daniel M. Bishop and Mervin E. Stevens, Landslides on Logged Areas in Southeast Alaska
"In many cases, landslides have increased greatly 5 to 20 years after clearcutting. This is because part of the strength of a soil mass comes from the anchoring effect of the tree roots. As the roots decay, susceptibility to landslides gradually increases."
-R.M. Rice, J.S. Rothacher and W.F. Meghan, Erosional Consequences of Timber Harvesting: An Appraisal. Proceedings on Watersheds in Transition
"...experimental watersheds throughout the country (United States) show a pronounced increase in annual streamflow after clearcutting."
-Jack Rothacher, Regimes of Streamflow and Their Modification by Logging
Healthy old-growth forest giant cedar and hemlock in the upper Coquitlam watershed.
"It is extremely important to maintain ground cover and to practice uneven-aged management - if, indeed, any logging at all - with subalpine and alpine species and on steep terrain in snow country."
-Glen O. Klock, Snowmelt Temperature Influence on Infiltration and Soil Water Retention
"Type of logging has a tremendous influence on soil stability, as does the intensity of cut - whether the area has been clearcut or selectively logged."
-C.T. Dyrness, Erodibility and Erosion Potential of Forest Watershed, International Symposium on Forest Hydrology
"The rate of soil transfer during a heavy, but not unusual, storm was forty-one times as great on clearcut land as on undisturbed old-growth forest and forty-six times as great where road failures occurred."
-J.W. Schwab, Mass Wasting: October-November 1978 Storm, Rennel Sound, Queen Charlotte Islands, British Columbia
