Outline of Forestry Impacts on Streams

Forestry Effects on Streams

Water Cycle

  • Loss of vegetation increases total flow volume in streams
  • Increased peak flows via:
  • reduced interception caused by removal of the forest canopy during harvesting
  • reduction in evapotranspiration caused by loss of vegetation
  • modified snow accumulation and melt rates
  • reduced infiltration due to frozen soil

 
Healthy Forests/Healthy Streams

  • Positive impacts of forests on streams
    • Shading (temperature moderation)
    • Temperature effects on community composition
    • Temperature effects on oxygen and metabolic rates
    • Stable flows positively impact fish habitat quality
    • Stable flows moderate suspended sediments/turbidity
    • Undisturbed forests reduce potential for erosion
    • Forests provide important instream habitat features (lwd, overhanging veg., etc.)
    • Forest and stream food webs are linked (diverse food sources)
    • Healthy forests play a role in nutrient transformation and inputs to streams

What can happen following forest harvest?
  • Hydrologic Alterations
  • Alters runoff-evapotranspiration balance, causing increases in flood magnitude and frequency, and often lowers base flow
  • Contributes to altered channel dynamics, including increased erosion from channel and surroundings and less-frequent overbank flooding
  • Runoff more efficiently transports nutrients, sediments, and contaminants, thus further degrading in-stream habitat. Strong effects from impervious surfaces and stormwater conveyance in urban catchments and from drainage systems
    and soil compaction in agricultural catchments
  • Riparian clearing/Canopy opening
  • Reduces shading causing increased temperature and P/R rates
  • Decreases bank stability
  • Decreases wood inputs
  • Increases nutrients and contaminants
  • Alters instream trophic structure (reduced organic matter input and retention)
  • Loss of Large Woody Debris
  • Reduces substrate for feeding, attachment, and cover
  • causes loss of sediment and organic material storage
  • reduces energy dissipation
  • alters flow hydraulics and therefore distribution of habitats
  • reduces bank stability
  • influences invertebrate and fish diversity and community function


Trout and their Streams

Stream fishes need:

  • Hydrology
  • Temperature
  • Nutrients
  • Sediments/Morphology
  • Food
  • Cover


How do healthy forests provide these needs?

  • Forests stabilize flows via reduced overland flow, interception and storage in plants/increased transpiration, increased surface storage (protection from sun and wind/reduced evaporation in soils)
  • Forests moderate temperature via shading and stabilizing flows
  • Forests are the primary source for organic matter to streams (CPOM and terrestrial inverts) and determine community composition (FFGs)
  • Forests reduce instream and overland erosion which impacts turbidity and substrate characteristics (siltation, sand deposition, embeddedness, etc.)
  • Forests provide a variety of chemical, physical, and biological inputs that support stream food webs
  • Forests provide LWD, creating diverse bedforms and important instream features utilized by fish


How can harvesting forest products affect trout and streams?

  • Hydrologic Alterations
  • Alters runoff-evapotranspiration balance, causing increases in flood magnitude and frequency, and often lowers base flow
  • Contributes to altered channel dynamics, including increased erosion from channel and surroundings and less-frequent overbank flooding
  • Runoff more efficiently transports nutrients, sediments, and contaminants, thus further degrading in-stream habitat. Strong effects from impervious surfaces and stormwater conveyance in urban catchments and from drainage systems
    and soil compaction in agricultural catchments
  • Riparian clearing/Canopy opening
  • Reduces shading causing increased temperature and P/R rates
  • Decreases bank stability
  • Decreases wood inputs
  • Increases nutrients and contaminants
  • Alters instream trophic structure (reduced organic matter input and retention)
  • Loss of Large Woody Debris
  • Reduces substrate for feeding, attachment, and cover
  • causes loss of sediment and organic material storage
  • reduces energy dissipation
  • alters flow hydraulics and therefore distribution of habitats
  • reduces bank stability
  • influences invertebrate and fish diversity and community function


Forestry BMPs and Trout Streams

How can we harvest forest products and maintain healthy streams?

  • Utilizing sustainable harvest techniques that promote native plant regeneration, soil conservation, and maintains a functional riparian zone
  • Protecting streams from erosion by utilizing thoughtful road placement and construction techniques, and using appropriate stream crossings or alternatives to stream crossings
  • Utilizing appropriate slash management practices


Forestry BMPs and how they protect streams and fish

  • Riparian Buffer Zones
  • Width considerations (slope, stream size, soils)
  • Species Composition


How RBZs protect streams:

  • Dissipate energy/slow velocities
  • Provide erosional resistance
  • Influence channel morphology (LWD, stable undercut banks, protect from lateral erosion/migration)
  • Protect forest soil and reduce overland flow and gulley erosion
  • Stream Crossings
  • Maintain connectivity, flow regime, and protect from erosion
  • Temporary stream crossings
  • Temporary bridges/timber mats
  • Fords
  • Permanent stream crossings
  • Culverts
  • Bridges
  • Road and Skid Trail Construction
    • Well placed, constructed, and maintained forest roads minimize impacts to streams
  • Slash Management
    • Properly place and disperse slash in areas where runoff will not wash slash into streams, lakes, or wetlands


Michigan Laws and Permits

What permits do I need for my forestry project?

  • To determine specific permit requirements, contact the DEQ Environmental Assistance Center or the local district DEQ service center.
  • Whether a permit is required or not, the landowner is responsible for preventing off-site sedimentation


Provide a list and summary of applicable laws/permits for forestry projects near water

  • Part 91 Soil Erosion and Sedimentation Control (SESC): A permit is required for any earth change that disturbs one or more acres of land OR that is within 500 feet of a lake or stream.  Part 91 is administered and enforced by various state, county, and local governmental agencies. Part 91 Agency guidance by county: http://www.michigan.gov/documents/deq/wrd-sesc-agency-list_539870_7.pdf
  • Part 305 Natural Rivers Act: Regulates all development and land uses, including timber harvest and stream crossings that are within 400 feet of a designated stream. Also includes minimum buffer widths by river.
  • Part 301 Inland Lakes and Streams: Protects the integrity of the land/water interface. Crossing a permanent or intermittent stream while skidding forest products or transporting them to a mill requires a Part 301 permit.


Provide contact information for agencies and other helpful resources