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Erosion. What is it?. Movement of soil materials by the action of water, wind or gravity. Background. Erosion is a problem when it results from, or is accelerated by our activities Vegetation and an “intact” forest floor limit erosion potential - PowerPoint PPT Presentation
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Erosion
What is it?
Movement of soil materials by the action of water, wind or gravity
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
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
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
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)
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
Steep Slope Areas Preplan skidding on steep rolling terrain Avoid skidding up and down steep
slopes (> 30%) where possible
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)
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
BMP’s for Erosion
Steep Slope Areas Some timber on steep slopes should
be bypassed because of safety, operational and site damage concerns
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
BMP’s for Erosion
Road Construction Use energy dissipaters such as
boulders, slash, etc. to interrupt water flow in ditches
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
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
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
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
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
BMP’s for Erosion
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.
Questions?