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Published byOlivia Gotts Modified over 9 years ago
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Erosion
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What is it? Movement of soil materials by the action of water, wind or gravity
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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
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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
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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
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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)
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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
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Steep Slope Areas Preplan skidding on steep rolling terrain Avoid skidding up and down steep slopes (> 30%) where possible BMP’s for Erosion
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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) BMP’s for Erosion
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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 BMP’s for Erosion
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Steep Slope Areas Some timber on steep slopes should be bypassed because of safety, operational and site damage concerns BMP’s for Erosion
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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 BMP’s for Erosion
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Road Construction Use energy dissipaters such as boulders, slash, etc. to interrupt water flow in ditches BMP’s for Erosion
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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 BMP’s for Erosion
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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 BMP’s for Erosion
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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 BMP’s for Erosion
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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 BMP’s for Erosion
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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 BMP’s for Erosion
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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.
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