Sawbill Monitoring Project: Inventorying Jack Pine-Aspen-Birch 10-15 Years Mechanical Site Prep and Planting (USFS)

Stand Information

Bent over trunks of snow damaged jack pine

State or Province:

Minnesota

Nearest city or town:

Tofte

Describe the location:

Sawbill Project Area, Tofte Ranger District, Superior National Forest.

Landowner:

US Forest Service

Cover-type:

Mixed Woods

MN ECS Native Plant Community System:

Fire Dependent

Plant community or habitat classification and growth stage:

FDn43b

Forest Health Threats:

Invasive plants competing vegetation

Estimated year of stand origin:

2005

Silviculture System:

Clearcut

Brief silvicultural objective:

Establish an even-aged mixed woods stand comprised of jack pine, aspen, paper birch, and balsam fir.

Soils:

Variable: silty clay loam to clay loam, loamy sand, rocks visible at surface.

Stand area:

15 acres

Treatment area:

15 acres

Overview

The Superior National Forest’s silviculture prescriptions are part of the National Environmental Policy Act (NEPA). The NEPA process includes proposal development, environmental analysis, and implementation of proposed activities. After the NEPA decision notice is finalized, the silviculture activities can begin in a given project area.

These NEPA prescriptions usually start with stands in mature forest condition. The regeneration harvest method is designated, followed by how the stand will be regenerated. Tending and intermediate treatments are completed based on need and whether funds are available to complete these types of activities. Five years after a timber harvest, stands are usually certified as reforested. Once stands have been certified, they may not be revisited for many years. However, the Superior National Forest would like to inventory reforested stands at 10-20 years after reforestation to determine if prescription objectives are being met.

There are several items that I would like to discuss. First, what was the desired future condition and the prescription for these stands? Management in the past was often more concerned with generating revenue from standing timber rather than desired future conditions. Consequently, the desired future condition and silviculture prescription can be hard to determine. For that reason, in this study I have recreated the desired future condition and silviculture prescription based on pretreatment stand conditions, management history, and current stand conditions. The second item is, does the prescription fit the site from an ecological stand point? Why or why not and how so? Third and finally, what would I do differently, and why?

Silviculture Objective(s)

Desired Future Stand Conditions:

• Even-aged mixed wood stand.
• Jack pine, aspen, paper birch, and balsam fir are the dominant species present, accounting for at least 1500 trees per acre and 50% of species composition.
• The trees in the stand are growing at an optimum rate and are resilient to insect and disease attacks.

Pre-treatment stand description and condition

Stand establishment and management history:

Original Prescription: Harvest Method – Clearcut, Mechanical site prep, Plant jack pine, Natural regen aspen, balsam fir, and paper birch.

2003: Clearcut, Bluemoon Sale, PU 5.

2004: Mechanical site prep, tractor scarification

2005: Planted, JP bare root

2006: 1^st year stocking survey, 90% stocked, 100% survival

2009: 3^rd year stocking survey; certified with 5387 trees per acre (76% paper birch, 13% aspen, 10% jack pine, low density white pine).

Pre-treatment growth and stocking:

Mature aspen-white spruce-balsam fir, 40-70 ft²/acre BA, 11” dbh, 50% brush and numerous brushy openings acccording to comments from 1986.

Pre-treatment forest health issues:

Snow damage and mortality in 20% of jack pine. Chokecherry thickets with raspberry in understory common throughout, perhaps these are areas where slash was piled after mechanical site prep. Suppressed dying red pine present in the understory. Fire scarred stump observed in site.

Landowner objectives/situation:

Short-term objectives:
• Harvest existing aspen, spruce, and fir before timber value is lost.
• Establish a mixed forest stand. Enhance tree species diversity by allowing hardwood and conifer species to regenerate in the stand.
• Provide sustainable timber products to local operators.
Long-term objectives:
• Fully stocked, mature, healthy mixed wood stand.
• Maintain or enhance species diversity.
• Maintain a strong conifer component in the stand. Recruit potential snags and downed wood into the stand.

Silviculture Prescription

Regeneration Harvest –
Primary treatment – Clearcut with reserves. Reserve 5% of stand area as a legacy of clumps of trees. Reserve clumps shall, wherever possible, be at least 2 acres in size with a basal area of 80 ft2/acre or more and a dbh of 6” or more. Reserve single trees shall be scattered throughout the stand and retained at a density of approximately 6 to 12 trees per acre. Reserve trees shall be windfirm and selected in order of preference as: white pine (if present), white spruce, quaking aspen, paper birch, and balsam fir.
Secondary treatment – Mechanically prepare the site for planting via tractor scarification. Scarify the ground to expose mineral soil and remove competing vegetation. Equipment shall work the soil to a depth of 3-4” on average.
Regeneration – Plant jack pine at a density of 600 tpa. Natural regeneration of paper birch, quaking aspen, balsam fir, white spruce, and white pine.
Intermediate Treatments – None conducted, but a release treatment or pre-commercial thinning would have and could still be of benefit to this site.

Post-treatment assessment

Forest Type: Jack pine (with aspen and paper birch component). DBH: 2", Height: 18 feet; Density: 3,480 TPA

Jack pine: moderate density, patchy distribution, 3” dbh, 18 ft. tall, 30% of composition
Quaking aspen: moderate density, patchy distribution, 2” dbh, 18 ft. tall, 30% of composition
Paper birch, moderate density, patchy distribution, 1” dbh, 14 ft. tall, 30% of composition
Choke/Pin cherry thickets (not crop trees, but the shrub is 20’ tall at this site) and brush, moderate density, patchy distribution, 2” dbh, 20 ft. tall, 5% of composition
White pine and balsam fir, low density, patchy distribution, 2” dbh, 12 ft. tall, 5% of composition.

Ecologically, current conditions are similar to a young FDn43 community at age 0-35 years old, but aspen would have dominated over jack pine. Under natural conditions, catastrophic fires would occur at regular intervals; the mechanical site preparation was a successful substitution for fire. Aspen and jack pine would have been the first cohort of trees to regenerate in this stand, similar to what is present, except the jack pine was planted at higher concentrations than likely would have regenerated naturally. Therefore, the prescription for this stand fits the Native Plant Community. However, the regenerating jack pine have had mortality of approximately 20% due to snow damage. Notes indicate 50% brush cover prior to treatment. The site continues to be brushy. An intermediate treatment that released the jack pine from deciduous competition may have prevented some of the snow damage. When heavy snow bent the brush and trees over the vegetation became tangled and remained bent over. If the brush had been absent or present in lower densities (from a tree release treatment) and the jack pine and other crop trees had been adequately spaced (from tree release) then the trees more likely would have reformed in an upright condition after a heavy snow event.

Plans for future treatments

The healthiest jack pine, aspen, paper birch, and white pine should be freed from brush by a pre-commercial thinning/release treatment. Release the best formed pine, aspen, and paper birch (those with no damage or disease, upright, straight, single stems) that are spaced approximately 8’ x 8’, but prioritize healthy trees over exact spacing. Use brush saws and chainsaws to clear all vegetation within a 2 foot radius of healthy crop trees. The stand should be monitored every 10-20 years to ensure stand and tree health is maintained.

Other notes

This case study was developed with support from the United States Department of Agriculture's National Institute for Food and Agriculture (USDA-NIFA), Renewable Resources Extension Act (RREA). Project #MIN-44-E02, principal investigator Eli Sagor, University of Minnesota.

Summary / lessons learned / additional thoughts

The purpose of the Sawbill Monitoring project was to review the previous prescription for a stand and answer three questions. The first question addressed the desired future condition and the prescription, following which I recreated the desired future condition and silviculture prescription based on pretreatment stand conditions, management history, and current stand conditions. The second question to answer was, does the prescription fit the site from an ecological stand point? Why or why not and how so? Third and finally, what would I do differently, and why? These three case studies also addressed a need to revisit stands at a more regular interval to determine if action needs to be taken. If a stand is certified regenerated and then not visited for decades the window for intermediate treatments may pass forest managers by and result in degraded quality when it comes time to harvest. Rather, revisiting a stand 10-20 years after its regeneration certification allows foresters to determine if prescription objectives are being met.

For this particular stand releasing crop trees would have prevented some snow damage which resulted in 20% mortality of jack pine. However, it is not too late for an intermediate treatment to open up growing space and release quality crop trees to maintain a mixed woods covertype.

Photographs