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Silviculture

Carl Alwin Schenck Stone - Support - College of Natural Resources at NC State University

The most common silviculture practice used on operational lands at Schenck Forest employs even-aged methods. Final harvests or harvests conducted to foster reproduction will range in size from 5 to 50 acres. The schedule for these harvests will take into account the size and conditions of adjacent stands to meet or exceed adjacency green-up guidelines. 

The specific type of harvest technique utilized depends on site factors, habitat, aesthetic concerns and the relative need for specific teaching examples. This may result in no harvests in a given year followed by a larger harvest. Over the timeline of this management period, we will not plan any more harvests than those specified in the allowable harvest schedule.

The target rotations for species in the forest are based on philosophical and pedagogical concerns of faculty members who teach and study there and not solely on financial considerations. The generally agreed upon rotations for operational lands are listed below:

SPECIESROTATION LENGTH
Virginia pine40 years
Shortleaf pine50 Years
Longleaf pine60 Years
Loblolly pine, natural39 Years
Loblolly pine, planted39 Years
Oak, yellow-poplar, sweetgum and other mixed hardwood60 Years

Silvicultural Management

At Schenck Forest, silvicultural treatments will vary depending on the previous stand, desired species composition and the density of the subsequent stand. Except where dictated by teaching, research, demonstration needs or by local aesthetic or other considerations, the predominant silvicultural strategy shall be even-aged for pine and uneven-aged for hardwoods.

The routine silviculture practices used for pine stands may include chemical site prep herbicide application, burning, seedling planting, fertilizer applications, pre-commercial thinning (PCT) and mid-rotation herbicide application. The reproduction harvest methods primarily used include clearcutting, seed tree harvesting, shelterwood harvesting or variations thereof. 

The routine silvicultural practices used for hardwood stands will differ slightly from pine stands. For example, chemical applications will be extremely selective and will likely be stem treatments as opposed to broadcast treatments. As with pine stands, burning will be an active part of hardwood silvicultural treatments. 

Hardwood stand regeneration will likely be natural regeneration from on-site seed source or coppicing. Planting hardwoods will not be a routine treatment. To limit the impacts of volunteer pine and undesirable hardwood species, fire or PCT treatments will be used to remove the undesirable stems.

Chemical Applications

Both chemical site preparation and mid-rotation herbicide applications are routine silvicultural treatments for pine species. Due to the irregular shape and location of individual stands, the vast majority of these applications will be done with ground equipment, skidder or backpack. 

All applicators are required to show proof of North Carolina Pesticide Applicator License with forestry category endorsement. Special management zones, property boundaries and other sensitive sites are required to be buffered during chemical applications. 

Standard prescriptions will include: imazapyr (2- or 4-pound active ingredient), triclopyr, glyphosate, metsulfuron methyl, sulfometuron and surfactant. Typically, a total volume of 30 gallons of herbicide per acre is applied.

Site preparation applications will typically occur within 12 to 18 months after final harvest, depending on weather, grow back and species composition. The exact prescription will be determined based on the pine species to be planted. 

Mid-rotation applications will be conducted within 12 to 24 months after the first thinning, again, depending on weather, greenup and species composition. The exact prescription will be determined based on the planted pine species. Depending on targeted pest or undesirable species, other specialized chemicals may be used. 

From time to time, both standard and specialized chemical applications will be reviewed by a qualified forestry pesticide consultant to ensure proper chemical type, rates and application techniques are used. 

Burning

Burning is an active method of the silvicultural treatment regime for both pine and hardwood stands. Scheduled burns will likely occur after final harvest of stands to reduce residual woody debris and facilitate planting. Subsequent burns will occur throughout the life of the stands to reduce competing vegetation and the accumulation of woody debris, as well as to promote the growth of desirable woody species, grasses and flowers. 

All burns will be planned and led by a North Carolina Certified Burner, and when possible a National Wildfire Coordinating Group (NWCG) Prescribed Fire Burn Boss Type 2. All personnel on burns will have a NWCG Fire Fighter Type 2 certification. Personal protective equipment is provided. 

Regeneration

As previously stated, hardwood regeneration will likely occur through natural processes such as seed-in-place or coppicing. Pine regeneration, on the other hand, will mainly occur through artificial planting. 

Depending on the target species and planting site, the planting density of pine will range from 430 to 540 planted trees per acre, with spacing arrangements of 5 to 10 feet in drill spacing and 10 to 15 feet in row width. The vendors for pine seedlings include but are not limited to the North Carolina Forest Service, International Forest Company and ArborGen.

The loblolly pine seedlings will be planted in containers or as bare roots, with genetic varieties selected using NC State Tree Improvement Cooperative’s performance rating system to select improved seedlings ideal for the soil type and climate range and seedlings with high volume gains, high rust resistance, low forking potential and high stem quality.  

Due to the low survival rates of bare root longleaf and shortleaf pine, these species will be planted using container seedlings. Currently, the availability of genetically improved longleaf or shortleaf pine is nearly nonexistent. For this reason, the planting selection for these seedlings will be less meticulous and will be based on availability and piedmont seed source. The selection for eastern white pine and Virginia pine will be based on availability and seed source.

Forest managers will target a two-year turnaround time, weather permitting, to have stands planted and back in production. All of the planted stands will need to achieve a survival rate that’s greater or equal to 80% after the first growing season in order to be considered successful. Any stands with a survival rate of less than 80% will be evaluated to determine if a total replant is needed or if spot planting will suffice to achieve desired stocking levels and spacing pattern.

Fertilization

Fertilizer applications will be conducted on a stand-by-stand basis. An analysis of soil conditions, leaf area, prior fertilization treatments, species and economic benefits will be used to determine timing, prescription and type of fertilizer to apply. The applications of fertilizer may occur at the time of planting or after thinning and may occur through either manual or mechanical application. Due to irregular shape and locations of individual stands, aerial fertilizer applications will be extremely limited.

Pre-commercial Thinning

PCT treatments will be conducted on an as-needed basis to remove competing woody stems from individual stands in order to enhance and encourage growth of desirable species, whether planted or natural. These treatments typically target loblolly pine, sweetgum and red maple and are conducted by hand crews with brush saws. Prescriptions vary based on desired species and stocking, but crews generally remove undesirable woody stems and/or diseased, deformed and suppressed stems to reach a target stocking level and approximate spacing pattern. Some treatments may be conducted using chemical basal bark or cut stump treatments.