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Forest Site Preparation
• Definition: Purposeful treatment of the site to prepare for the regeneration process
• Site preparation practices include:– Remove unwanted vegetation, slash and stumps from a site
before/immediately following a regeneration method
Silvicultural Objectives of Forest Site Preparation
• Control competing vegetation
• Create a seedbed environment that favors target species• Soil Scarification
– Loosening of the upper soil or breaking up the organic layer
– Removing undecomposed litter and humus to expose mineral soil
– Mixing surface organic materials with mineral layers beneath them
– Mechanically removing competing vegetation or interfering debris
Silvicultural Objectives of Forest Site Preparation
• Alter physical attributes of the rooting zone– Reduce soil compaction– Improve drainage
• Facilitate planting of seedlings– Remove physical obstructions such as slash, standing trees, stumps (this is especially
important for machine planting)
• Aesthetics
Site Preparation Objectives in the Central Hardwood Region
• Site preparation prior to final harvest
• Control competing vegetation
• Alter seedbed to promote establishment of advance tree reproduction
• Proactive removal of noncommercial trees that would inhibit seedling development following a harvest
• Post-harvest site preparation
• Control competing vegetation
• Remove trees remaining from previous stand that are inhibiting seedling development
• Alter seedbed to promote germination of light seeded species
• Prepare area for tree planting
Categories of Forest Site Preparation
1. Mechanicala. Competition control
b. Slash manipulation + competition control
c. Seedbed manipulation
d. Competition control + seedbed manipulation
e. Alter physical attributes of the rooting zone
2. Chemical
3. Prescribed Firea.
Mechanical Competition Control
Manual Felling:
Mechanical Competition Control
Manual Girdling:
Shearing: Cuts down standing vegetation using a large tractor with KG blade or V-blade
Mechanical Competition Control
Shearing: Cuts down standing vegetation using a large tractor with KG blade or V-blade
• Benefits–
– Provides some competition control, but is usually inadequate without follow-up treatment
• For planting, shearing is usually to facilitate further mechanical site prep, such as rake-and-pile or drum chopping
• Shearing is also used to complete silvicultural clearcutting in hardwoods
Mechanical Competition Control
Drum chopping: use a large cylindrical drum with sharp blade, pulled by a large tractor
• Breaks debris into smaller pieces, gets it closer to the ground (for more effective burning);
• Destroys some rootstocks (usually preceded by shearing)
Mechanical Slash Manipulation and Competition Control
Drum chopping
• Benefits:– Provides some competition control, but it may be poor or inconsistent,
due to problems with sprouting
– Provides some facilitation of planting, which may be greatly improved by burning
– Provides some improvement in soil conditions (increased infiltration of surface runoff, reducing erosion)
Rake-and-pile (root-raking, windrowing: use a large tractor with a root-rake to move surface debris and stumps, and to rip out rootstocks
• It normally follows shearing
• Most commonly, debris is piled into windrows
• Benefits
Mechanical Slash Manipulation and Competition Control
Rake-and-pile (root-raking, windrowing)
• Potential problems:– Erosion/sedimentation
– Movement of topsoil (often results in a reduction in site productivity)
• Countermeasures:– Avoid rake-and-pile on steep slopes and highly erodible soils
– Put windrows on contour
– Do not remove litter layer unnecessarily
– Use only skilled and careful machine operators
– Do not use a straight blade for raking!
Mastication: mechanical grinding of logging slash, whole trees, and brush
Mechanical Slash Manipulation and Competition Control
Disking: done with large heavy disks, pulled by a large tractor
• Knocks down small material, rips up smaller rootstocks
• Benefits: – May provide good competition control
– Provides some facilitation of planting
– Can decrease compaction
Mechanical Seedbed Manipulation and Competition Control
• Bedding: combination of plowing and disking to create raised beds for planting seedlings
• Usually follows rake-and-pile
• Benefits– Improves soil aeration, both by raising above a high water table and by
breaking soil compaction
–
– Gives additional competition control
– On uplands, positive benefits of bedding include:
• Allow beds to settle for six weeks before planting
Mechanical Alteration of Rooting Zone
• Subsoiling (ripping): utilizes a long (24-48 "), narrow, sharp plow for cutting through compact soil or a restrictive soil pan
• Usually follows other methods, or is used in old fields that have a plowpan
• Benefits
Mechanical Alteration of Rooting Zone
Combination Treatments
• Combination treatments
The Savannah “3-in-1 plow”- employs a specialized combination of ripping, plowing, and bedding, (often with shearing) in one pass
Soil Scarification to Improve Oak Establishment
• What is Soil Scarification?
The use of mechanized equipment to create a shallow soil disturbance in desired areas that incorporates acorns into the soil, while providing competition control.
Factors Influencing Oak Seedling Establishment
• Acorn Production
• Predation: mammals, birds, insects
• Seed moisture content
• Leaf litter depth
Acorn Positions in Forest Floor
• Unfavorable:
1. on litter layer surface
2. positioned within a thick litter layer
• Favorable:
1. buried 1 to 2 inches deep in soil
2. in contact with mineral soil, covered with leaf litter that is not too thick
Why Use Soil Scarification for Oak Regeneration?
• Increase germination through incorporation
• Provides competition control
So. IL Bottomland Oak Disking – Results Impact of Treatment on Oak Seedling Density
0100020003000400050006000700080009000
10000Control Scarified
Pretreatment Year 1Stand A Stand A Stand BStand B
Seedlin
gs
Ha
-1
So. IL Bulldozer and Brush Rake Study
• Scarification treatment:– 78 hp crawler tractor
– 8 ft, 6-tooth brush rake
– Rake inserted into the soil approx. 4 inches
– Operation damaged or uproot midstory trees
Mature, mixed oak upland forest
So. IL Bulldozer/Brush Rake Study – Results
Impact of Treatment on Oak Seedling Density
0
1000
2000
3000
4000
5000
6000
Control Scarified
Pretreatment Year 1
Seed
ling
s H
a-1
Overall Trends
• The results suggest scarification may:
– Increase germination and initial establishment
– Influence competing vegetation
– Enhance competitive position of oak seedlings
– Be a useful management tool in both upland and bottomland forests
Note: abundant acorns must be present
Reasons for Using Chemical Site Preparation
• Kill dense or unwanted vegetation that:
• Kill or desiccate ground vegetation to improve fuel conditions for prescribed burning
• Prevent understory development
• Inhibit seed germination of weed species
Advantages of Chemical Site Preparation
• Effectively kills a broad array of weeds and competing plants
• Can kill targeted species when applied with proper timing, dosage, and formulation
• Prevents sprouting from stumps and root systems
• Does not disturb surface or affect the inherent site productivity potential
• Works equally well in treating large or small areas in a number of ways and times of the year
• Proven cost-effective, particularly for broadcast and other mechanized applications over large areas
Chemical Site Preparation
Herbicide Labels
• Labels are required legal documents: uses other than those listed are illegal
• All forestry herbicides must pass a rigorous approval process for EPA (sets standards for effectiveness and safety
• Important information that is listed on herbicide labels:– Ingredients – Precautionary statement
– May include a restricted use designation– Information and directions for approved uses (including species "controlled")– Instructions for storage and disposal
Herbicide Toxicity
• Toxicity: Those labeled for forestry uses are low in toxicity, are non-persistent, and do not bioaccumulate
• They are targeting plants, usually blocking or overstimulating plant enzymes
• None are toxic to birds or mammals at expected levels of exposure or ingestion
• LD50: dose (wt/body wt) fatal to 50% of test organisms. Lower # more toxic
• They are rapidly tied up or broken down in biological and soil systems
Herbicide Application
• Methods– Broadcast
– Spot or strip
– Individual stem
• Chemicals used should be labeled for the application
Herbicide Tank Mixes
• Tank mixes: two or more herbicides are mixed together– Wider spectrum of control
– Most commonly applied as broadcast foliar and/or soil-active
– Do not plant tree seedlings for 3-6 months after most soil-active chemicals (esp. for Tordon, Velpar)
– Commonly followed by hot prescribed fire (“brown and burn”) {in order to facilitate planting}
– Tank mixes common with broader spectrum of control and quick brownup
• Arsenal/Accord, Tordon/Garlon
Herbicide Tank Mixes
Application in spots or strips ("bands")
• Hand carried sprayers or spreaders, spot guns, tractor-mounted sprayers or spreaders
Prescribed Fire for Site Preparation
Primary Uses
• Reduce slash, debris, and undecomposed litter, and release nutrients in accumulated organic materials
• Kill interfering vegetation or reduce understory plants to alter visual qualities in a stand
• Influence plant succession or increase ecological diversity by perpetuating fire-dependant plant communities
• Reduce accumulation of hazardous fuels
• Reduce the thickness of forest floor or expose mineral soil
Uses of Burning for Site Preparation
Secondary Uses
• Open cone and other fruiting structures to release seeds– Species with seratonous cones (e.g., jack pine and lodgepole pine)
• Destroy pests and harmful organisms and the habitats that sustain them
• Increase water yields by altering the kind and size of vegetation and reducing transpiration
• Induce sprouting of surviving vegetation to improve cover, browse or forage production
Effects of Prescribed Burning
Effects will depend on:• Amount and nature of fuel
– Pine litter more flammable than hardwood litter
• Size of vegetation to be killed {poor top kill if >3" diameter}
• Number of sproutable rootstocks (maximum kill for one burn usually around 20%, less for a winter burn)
• Timing of burn – most kill in growing season (optimum just after leaf out), least in dormant
season;
– best consumption with least green or living vegetation, i.e., in fall/winter or after herbicide browning
– higher erosion potential with fall/early winter burn (soil stays bare all winter)
– late spring burn will impact ground nesting birds (e.g., wild turkeys)
Potential problems in using prescribed burning
• Scheduling: need proper fuel conditions, weather, and available manpower
• Requires experienced supervision for planning and implementation
• Smoke management potential problems: air pollution, P.R., legal restrictions and liability
• Containment issues and liability
• Fire may damage or kill residual trees
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