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

How site preparation fits into a silvicultural system

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 Site Preparation

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

Disk Scarification

So. IL Bottomland Oak Disking – Results Impact of Treatment on Oak Seedling Density

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So. IL Bottomland Oak Disking - Poison Ivy

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

Bulldozer/Brush Rake Scarification

So. IL Bulldozer/Brush Rake Study – Results

Impact of Treatment on Oak Seedling Density

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Control Scarified

Pretreatment Year 1

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So. IL Bulldozer/Brush Rake Study – Results

Impact of Treatment on Midstory

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

Chemical Site Preparation

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

Site Preparationand Stand Yield

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

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