Vegetation Management Alternatives
Section II. What are the alternatives and what is their silvicultural effectiveness?
Al Wiensczyk, FORREX...
What are the Alternatives?Methodology
Reviewed the scientific literature for information
Used experiential knowledge of project team and others
Gathered info on species autecology and treatment effectiveness
Very limited info on some treatments, quite extensive on others
Similarly very limited data on some competitive species – lots on others
Canadian Forest Management Database Dean Thompson http://www.glfc.forestry.ca/cfpm/index.cfm?lang=eng
What are the Alternatives?CCFM Database
What are the alternatives? Non-crop vegetation in the boreal forest
Positive or negative effects on crop trees Depends on
Autecology of respective species (including reproductive strategy).
Non-crop species density Non-crop species size relative to that of the crop
trees Differences in site quality
Effect may change over time
What are the alternatives? Autecology information
Life Form/species
Reproductive strategy
Uses and Benefits Effects on conifers
TreesTrembling aspen Populus tremuloides
• Suckers• Basal sprouts
(rare)• Seed: wind
(rare)
• Crop tree• Nutrient rich litter aids in
nutrient cycling and increases soil fertility.
• May reduce weevil damage• Provides browse, cover and
nesting habitat for ungulates, small mammals and birds.
• Provides food for beaver• Buds are eaten by ruffed grouse
• Reduces light availability
• Competes for growing space
• Competes for rooting space
• May cause whipping damage
ShrubsSitka/green alder Alnus viridis/ Alnus crispa
• Seed: wind/water
• Basal sprouts
• Nitrogen fixation improves site fertility
• Builds up site organic matter• Stabilizes slopes and controls
erosion• Suppresses grass and raspberry
competition
• Reduces light availability
• Reduces moisture availability
• Reduces nutrient availability
• May cause snow press
What are the alternatives? Autecology Information
Life Form/Species
Response to Disturbance
Overstory removal
Fire Cutting Mechanical Site
PreparationLow
intensityMedium to
high intensity
Trembling aspen Populus tremuloides
•Root suckering, some stump sprouting
•Winter logging 4x more suckers
•Regen from seed on exposed mineral soil
•Vigorous sprouting when organic layer disturbed but not removed and root systems not damaged
•Adapted to environment with recurring fires;
•Regenerates from suckers
•Spring fires – increased regeneration
•Sprout from stump or suckers;
•Cutting in June – lower number of suckers
•Sucker production proportional to degree of cutting;
•Girdling during growing season effective
•Surface treatment will increase sucker production
•Seeding on mineral soil (minimal)
•High cultivation treatments may control aspen
Sitka/green alder Alnus viridis - Alnus crispa
•Increase in stem numbers
•Stimulated more by winter than summer logging.
•Often favoured by burning;
•Killing cambium at ground level will kill plant.
•If only stem killed will resprout from stumps.
• Control
•Increase in stem numbers through stump sprouts; July and August – least sprouting and height growth
•Treatments that remove roots – greater success
•Seeds in to disturbed sites
Vegetation Management Treatment Options Decision Making Process (from Wagner et al. 2001)
What are the alternatives?
Silvicultural activities
(harvesting, site
preparation, thinning)
Autecological characteristics of unwanted forest plants
Desired stand
Yes
Yes
No
Prevention loop
Removal loop
Release treatments
Favourable environment
No
Alter silvicultural activities
What are the alternatives? Treatment Groups
Harvesting Systems Physical Thermal Cultural Chemical and Biological spray
What are the alternatives? Silviculture and harvest systems
Silviculture System Clearcut, modified clearcut, shelterwood, selection
Harvest disturbance Influenced by
Harvest system Season of harvest Equipment used Operator training and skill
Harvest System Full tree, tree length, cut-to-length
Mechanical Site preparation Brushing
Manual Motor-manual Mechanical
Girdling Mulches
What are the alternatives? Physical Treatments
What are the alternatives? Thermal Treatments
Prescribed Fire Steam
Vegetative Reproduction Sexual Reproduction
Shoot OriginSprouts
Root Origin SproutsWindborne
SeedSeed Bank
e.g., maple, alder, birch,
dogwood, hazel, willow,
Labrador tea
Roots inorganic layer
Roots inmineral soil
e.g., grasses, birch, fireweed, poplar, willow
e.g., dogwood, cherry, rose, raspberry, blueberrySilvicultural
treatment Microsite Category e.g., grasses,
blueberrye.g., poplar,
rose, raspberry
None Undisturbed 0 0 0 0 0
Harvest Overstory removed; ground undisturbed 0 to
Mechanicalsite
preparation
Upland mineral soil
Organic partially displacedL and part of F (e.g. shallow screef)
LFH removed and mineral soil either:
Depressed (deep screef) to
Level (screef) to
Raised (mineral soil mound) to
LFH inverted with mineral soil cap (mineral mound on organic layer)
to to
LFH and mineral soil mixed (tilling) to to
Lowland Organic soil
Part of Of removed (e.g., by shearblading) to N/A
Drainage of layer (e.g., by ditching) N/A 0
Prescribed fire
Light
Moderate
Severe
Cutting Active < 25 cm - -
> 25 cm - -
Dormant < 25 cm - -
> 25 cm - -
Microsite descriptionEffect of disturbance on reproduction = promotes ( = strongly promotes)0 = no effect = discourages ( = strongly discourages)
What are the alternatives? Cultural Treatments
Seedling Culture Cover Crops Grazing
What are the alternatives? Chemical and Biological Spray Treatments
Herbicides Application methods
Biologicals
Vegetation Management Alternatives
Section III: What are the environmental consequences of using silviculturally effective alternatives?
Kathie Swift, FORREXWayne Bell, OMNR
What are the environmental consequences? Environmental effects
Lots of literature available on the effects of some treatments, less for others
Due to complexity of responses, focus put on principal messages
Treatments can have a positive effect on one element and a negative effect on another
Air Quality Soil Properties/Nutrition Water Quality and Quantity
Photo: Utah Bureau of Land Management Photo: Rhodes University
What are the environmental consequences? Abiotic Values
Plants (diversity) Fish/Fish Habitat Terrestrial Invertebrates Amphibians and Reptiles Song birds Small Mammals Mid-large Mammals
What are the environmental consequences? Biotic Values
Stand/Landscape changes
What are the environmental consequences? Spatial Values
Environmental Value
Harvesting System Physical Treatments
Thermal Treatment Cultural Treatments
Chemical and Biological Spray
Treatments
Water Quality/ Quantity
All harvest systems
Sedimentation issues
Road construction machine use around streams and stream crossings.
Steep slopes Can change soil
properties → surface water flow
→ risk of erosion (Wells and Jorgensen 1979).
Windthrow post harvest
→ sedimentation during seasonal runoff
MSP Can ground
water table. Can change soil
properties
→ overland flow
→ soil erosion and nutrient loss
→ water quality and the aquatic environment (Chang 2006).
Steep slopes can exacerbate the issue.
Prescribed Fire Addition of
biocarbonates, nitrates, ammonium, and organic nitrogen from ash
Not usually concentrated enough to pose a health risk to humans or animals (Chandler et al. 1983, Richter et al. 1982)
However some issues identified in northern Quebec and Alberta studies
Grazing by ungulates
Poor livestock management practices
allowing grazing ungulates to concentrate in streams and riparian zones
→ water contaminants → water temperatures (Foster 1998).
Ground and aerial application
Potential contamination of streams principle concern
May enter forest streams by
direct application, leaching through soil profile,
mass overland flow Rapid dilution with
downstream movement reduces concentration.
No hazard when care taken to protect streamside vegetation, and stream from direct contamination (Pritchett 1979)
What are the environmental consequences? Example of how information is presented
What are the environmental consequences? Example of how information presented
Silviculture practice
Biotic Biotic/Abiotic Abiotic
Canopy # Tree species
Treediameter
Snags Downed woody material
Organic matter (LFH)
Mineral soil Rutting or Compaction
Physical
Logging ↓↓ ↓↓ ↓↑ ↓↓ ↓↑ ↓ ↑ ↑↑
Thinning ↓ ↓ ↑ ↓ ↓ ↓ ↑ ↑
Mechanical SIP
↓ ↓↑ ↑ ↓ ↓ ↓ ↑ ↓↑
Brushing & girdling
↓ ↓ ↑ ↑ ↑ ↓ 0 0
Mulching - - ↑ - - ↓ ↓ ↑
Thermal
Prescribed burning
↓↓ ↓ ↓ ↓↓ ↓↓ ↓↓ ↑↑ 0
Cultural
Seedling ↓↓ 0 ↑ ↓↑ 0 0 ↑ ↓↓ 0
Cover cropping
↓ 0 ↑ 0 0 ↑ ↓↓ 0
Animal grazing
↓ ↓ ↑ 0 ↓ ↓ ↑ ↓
Chemical & Biological
Chemical ↓ ↓ ↑ 0 0 0 0 0
Biological ↓ ↓ ↑ 0 0 0 0 0
Fertilization ↑ 0 ↑ 0 0 ↓ 0 0
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