Erosion

1. Erosion

2. What is it? • Movement of soil materials by the action of water, wind or gravity

3. Background • Erosion is a problem when it results from, or is accelerated by our activities • Vegetation and an “intact” forest floor limit erosion potential • Harvesting can lead to erosion problems by removing the canopy and destroying lesser vegetation

4. Impacts of Erosion • Possible deposition of soil in waterways, damaging fisheries and aquatic ecosystems • Damage to roads, reforested areas and forest stands • Gravitational erosion (landslides) may cause extreme damage to the environment, property, and threat to human life

6. Impacts of Erosion • Erosion may reduce site productivity by • Displacing forest humus and topsoil layers • Removing or destroying soil structure of fine-textured mineral soils • Preventing plant establishment • Covering top soil layers with subsoil

8. Sensitive Sites for Erosion • Steep slopes • Wind-deposited soils (dune areas) • Deep alluvial deposits, especially adjacent to major river systems • Water crossings and all riparian areas • Road construction areas (unstable cuts, fills ,ditching)

9. BMP’s for Erosion • Steep Slope Areas • Risk of erosion increases with slope • Even minor rutting may cause erosion problems on slopes • Risk of damage and environmental significance is highest on fine textured soils

11. BMP’s for Erosion • Steep Slope Areas • Preplan skidding on steep rolling terrain • Avoid skidding up and down steep slopes (> 30%) where possible

12. BMP’s for Erosion • Steep Slope Areas • Winch wood off short slopes, or reach and remove it with a buncher • Dispersed skidding may be preferred to limit the creation of ruts on slopes • Cross-slope skidding may be preferred on moderate slopes with steps (within safety limits)

14. BMP’s for Erosion • Steep Slope Areas • Avoid skidding through narrow valley drainage ways • Avoid even minor rutting on slopes • Discontinue skidding sooner (e.g., due to wet weather conditions) on hilly terrain

15. BMP’s for Erosion • Steep Slope Areas • Some timber on steep slopes should be bypassed because of safety, operational and site damage concerns

16. BMP’s for Erosion • Road Construction • Maintain stable slopes on ditch line, road fills and cuts • Maintain 1:1 sloping of exposed material • Reinforce slopes (re-vegetate or use logging debris) • Crown and grade road surfaces

18. BMP’s for Erosion • Road Construction • Use energy dissipaters such as boulders, slash, etc. to interrupt water flow in ditches

19. BMP’s for Erosion • Road Construction • Plan to keep runoff water and sediment away from riparian areas • Use diversions such as tap ditches to direct run off water into areas of undisturbed vegetation or settling ponds

22. BMP’s for Erosion • Aeolian Soils • Roads and landings built on “blow sand” (aeolian sands) are subject to wind erosion • Limit the size of landings and all areas of exposed soil

24. BMP’s for Erosion • Aeolian Soils • Cover retired landings, road cuts, borrow pits (road ways) with duff, logging debris or chipper debris • Replant these areas quickly (Pj or Pr) • Avoid heavy site preparation that may promote wind erosion and impede reforestation

26. BMP’s for Erosion • Deep alluvial soils • Limit the extent of clearcut harvesting (size of blocks, total % of area) on these sites adjacent to large rivers • Plan smaller cuts with prolonged return periods

27. BMP’s for Erosion • Riparian Areas • Erosion in riparian areas is a significant environmental problem • Adhere to guidelines for riparian areas • Re-vegetate or reinforce exposed soils in crossing areas

28. Best Management Practices • Riparian Areas • Manage ditch line runoff to minimize sedimentation • Maintain 100 meter “no grubbing zone” (as per guidelines) • Plan water crossings to take advantage of low slope areas, rocky shores, etc.

29. Questions?