Introduction to Silviculture Treatments, Site Preparation Learning Objectives • Know the nature and purpose of silviculture treatments • Know the biological, operational and administrative considerations in choosing treatments. • Understand how microsite conditions are manipulated through site preparation. • Understand the distinction between site preparation and site degradation.
Successful regeneration depends on: •Suitable genetic material •Viable seeds, seedlings, vegetative material •Suitable microsites and environmental conditions •Good initial establishment •Unencumbered growth
Silviculture Treatments
• The goal of silviculture treatments is to move the site/stand from its current condition towards the desired future condition.
• This includes modification of soils, vegetation, micro- and site-level climate.
• Treatments are selected based on biological, ecological, operational, economic and societal considerations.
Treatment phases include: • Site preparation • Regeneration • Stand tending (pre-commercial thinning,
fertilization, pruning • Commercial thinning • Harvesting Vegetation management and forest health
management occur throughout all phases.
Site prepare to modify: •Logging slash - amount, distribution, suitability for insects •Vegetation - amount, distribution, species composition, growth rate •Forest floor - depth, distribution •Mineral soil - temperature, drainage, bulk density
Categories of site preparation: •Prescribed fire •Mechanical •Herbicides
In choosing method and equipment consider: •Physical and biological effects on microsite properties, crop plants and non-crop organisms. •Operational requirements and constraints. •Social issues, administrative and legal requirements.
Effects of site preparation on seedling environment
Vegetation competition – light:
at 4 years
Soil temperature:
A B C
Which site prep treatment produces best conditions for growth?
… in boreal and cool temperate zones, air and soil temperatures are rarely warm enough for optimal growth:
Nutrients: mineralization of forest floor nutrients (primarily nitrogen) is greatest on mounds or plow berms. Scalping can reduce nutrients.
Soil bulk density and root growth:
Prescribed Fire What kind of planting spots can fire create? Operational considerations •Must maintain fire weather stations and records •Calculate fire weather and venting indices •Need to inform government agencies •Be prepared to take advantage of narrow burning windows •Effectiveness depends on fire severity (too severe or not enough) •Provide public information
Recovery of non-crop competitors varies with species. Favors fire adapted species.
A Spring, before leaf flush B Summer, after full leaf out C Fall, after leaf drop D A or C
The best time to burn is:
Spring and fall burns give better coverage, but plants resprout more. D
Mechanical Site Preparation
Operational considerations •Decide on optimal microsite and pattern •Match implement to desired microsite •Match prime mover to site and implement (tool) •Avoid site degradation •Need access to site and skilled operators
Mechanical site preparation enables different patterns of spots…
… and different kinds of spots:
raised
level lowered
soil material
A
B
C
Which spot is best for a wet rich site?
These spots have different properties and can be used to offset site growth limiting conditions:
Forwarder Excavator
Skidder
Crawler Human
Prime Movers: Prime mover
Push/Pull/ Lift
Speed Machine Size Ground Pressure
Terrain Conditions
Human Push, Pull, Lift
Slow Low ground pressure
Any
Crawler Push, Pull Slow Medium - Large; High ground pressure
Gentle to moderately steep <35%
Skidder Pull, (Push) Fast Large; High ground pressure
Gentle <15%
Forwarder Pull Fast Large; Moderate ground pressure
Gentle <35%
Excavator Lift Slow Small - large; Low - moderate ground pressure
gentle to steep <50%
(see line drawings on p. 157-161 of RBCF)
http://www.youtube.com/watch?v=e3luK2nkCp8
Brush rake
Slash rake
bucket
Rake
Mulching head
Prime mover/ Action
Implement Treatment Coverage
Crawler / Push Straight blade
move or pile slash; shear brush above ground
uniform or strip
Brush or Slash rake
move or pile slash; remove brush (tops and some roots), break up upper soil
uniform or strip
V-blade move slash; shear brush above ground
strip
Excavator/ Lift Mounding bucket
invert humus or mineral mounds
spot
Slash rake move or pile slash spot
Mulcher chop brush and slash, mix plant debris, humus and mineral
spot
Implements:
Plow Disk trencher
Ripper bar Scarifier/mounder
Bedding plow
Drag scarifier
Prime mover/ Action
Implement Treatment Coverage
Skidder, Forwarder, (Crawler)/ Pull
Plow break up hard soil, drain, create terraces and linearly inverted mounds
strip
Ripper break up hard soil strip
Disc trencher
scalp and invert forest floor along trench
strip
Patch scarifier
scalp and invert forest floor spot
Mounder invert humus or mineral mounds
spot
Bedding plow (discs)
mix humus and mineral uniform or strip
Drag scarifier
distribute cones, lightly scalp and mix organic and mineral
uniform or strip
Implements cont…
Which spot is best for this site?
A B C
Raised Neutral Lowered
What prime mover and implement would you use on this site?
A B C D
Skidder, disk trencher Crawler, blade Excavator, rake Human, shovel
Site degradation is damage to the productive capacity of a site. Avoid these kinds of impacts:
Site degradiation cont….
In Summary… Site prepare to: •Modify logging slash, vegetation, forest floor, and mineral soil •To improve microsite quality •To reduce fuel and pest hazards •To improve planter access
Match method to microsite type and pattern, and to site conditions. Don’t degrade site by burning or scalping too much forest floor, or by compaction.
Role Playing 1. Foresters: a) What information and instructions do you need to give a
site prep contractor who is going to prepare your SP site?
b) How will you ensure quality and avoid site degradation?
2. Contractors: a) What do you need to know if you are going to bid on
this project? b) What will motivate you to produce a quality job and
avoid site degradation?