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?