47.664723, -93.262129
Overview
This site was one of the first final harvests of natural origin red pine (NORP) on School Trust land in the Hibbing area. This case study looks at the use of both natural and artificial regeneration practices to regenerate a NORP site in a manner that mimics the structure and diversity of a stand reinitiated by catastrophic fire. Mixed species spatially variable planting was used to provide a level of insurance that we would successfully regenerate a healthy, fully stocked, mixed red pine stand that would continue to provide future forest products and revenue to the School Trust.
Figure 1. Bear Lake NORP with variable density planted red pine and mature white pine reserves
Silviculture Objective(s)
Use a combination of natural and artificial regeneration practices to regenerate a natural origin red pine site with characteristics that mimic a natural origin stand in structure and diversity, while maintaining red pine as the dominant species.
Pre-treatment stand description and condition
Stand establishment and management history:
Around 1917 this stand was established through some catastrophic event. This stand was thinned multiple times over the past 20 years. These thinning treatments consisted of a free thin targeting non-red/white pine species such as jack pine, aspen, balsam, and paper birch, followed by a thin from below targeting red pine with poor form or those in the intermediate and co-dominant crown classes.
Pre-treatment species composition:
Stand composition included 14.5 cord/acre of red pine, 6.5 cord/acre of white pine, 2 cord/acre of white spruce, 2.1 cord/acre of paper birch, 2.24 cord/acre of aspen and 0.7 cord/acre of balsam fir. Understory composition included patches of advanced regeneration of white pine, white spruce, balsam fir and aspen, along with patches of heavy hazel brush.
Pre-treatment forest health issues:
Diplodia shoot blight concerns.
Landowner objectives/situation:
Minnesota’s Permanent School Fund receives income from economic activities on School Trust Lands which are managed by the MN DNR. Revenue on School Trust Lands is generated from forest management amongst other activities. Forest management activities on School Trust lands are planned and carried out by MN DNR.
As it relates to forest management on School Trust Lands, MN DNR has the authority and responsibility to achieve the goals outlined in Minnesota Statute, Section 84.027, Subd. 18 including:
- manage efficiently and with undivided loyalty;
- reduce operating expenses and maximize revenues deposited in the Permanent School Fund;
- maximize long-term economic returns while maintaining sound natural resource conservation and management principles;
- balance short-term revenues and long-term interests so that long-term benefits are not lost in an effort to maximize short-term gains;
- maintain the integrity of the trust and prevent the misapplication of its lands and its revenues.
Silviculture Prescription
Clearcut with reserves final harvest on 18 acres, removing all red pine due to Diplodia concerns, along with harvesting white pine, white spruce, aspen, paper birch and balsam fir. Reserve white pine and aspen as directed by forester along with designated reserve along Bear Lake Rd. Reserve all non-hazardous snags. Broadcast full tree skidding during dry, non-frozen soil conditions to set back the heavy hazel brush and scarify the site for regeneration. Pile slash and chip or burn piles to remove as much of the Diplodia inoculum on cones and slash as possible. Follow harvest with a spring planting of red pine (600 trees/acre.) and jack pine (200 trees/acre.) at an average of 800 trees/acre incorporating a variable density spacing technique. Dispute resolution team directed local area to use a local planting contractor to help facilitate variable density planting, along with planting the majority of jack pine along the reserve area to provide a buffer between residual red pine and regeneration. Mechanical brush saw release as needed.
What actually happened during the treatment
The final harvest on this site took place in October 2016 using conventional logging equipment. The harvest removed 359 cords of pine species, 37 cords of white spruce, 38 cords of paper birch, 22 cords of aspen and 13 cords of balsam fir. Scattered white pine and aspen were reserved as designated by the forester, along with clumped reserves. Scarification from full tree skidding operations was decent across the site, but not maximized. The slash was piled at the landing and chipped for biomass. Throughout approximately 2 acres in and around the landing, slash, debris, and chips were raked into windrows.
In late April 2017, the site was planted with a local planter over several days with 2-0 red pine and 1-0 jack pine container seedlings from PRT. Total seedlings planted on the site were 442 red pine/acre and 271 jack pine/acre, for 713 trees/acre. Mechanical brush saw release of conifer seedlings completed August 5, 2021 in partnership with The Nature Conservancy. Mechanical release was chosen instead of chemical to help retain aspen, birch, maple and other species of diversity on site, but in a more intermediate/co-dominant canopy position.
Post-treatment assessment
In the fall of 2017 the entire site was stocked with adequate crop trees. Composition was 357 trees/acre of red pine with 57% stocking, 304 stems/acre of jack pine with 64% stocking, 107 trees/acre of white pine with 21% stocking, and 179 trees/acre of balsam fir with 36% stocking (Table 1). Competition numbers were low after the first growing season.
Table 1. Fall 2017 regeneration survey with density and stock by crop and competition species.
Table 2. Fall 2019 regeneration survey with density and stock by crop and competition species
Table 3. Fall 2021 regeneration survey with density and stock by crop and competition species
In the fall of 2019, stocking and density had increased for nearly all crop tree species, and competitors had outgrown crop trees and were occupying more growing space stocking 100% of the site (Table 2).
In the autumn of 2021 mechanical brush saw release of crop trees from competition occurred. Following release, species initially present in 2017 and 2019 from artificial and natural origin had similar density and stocking (with the exception of balsam fir which was likely reduced during release activities; Table 3). There was a diversity of crop trees on site. White spruce was present on regen plots. Natural regeneration of bur oak, red pine and jack pine was also observed.
Plans for future treatments
Additional mechanical brush saw release as needed.
Costs and economic considerations
Revenue: final harvest- $21,872.06 or $1,208.40/acre.
Site prep: slash and debris raked into windrows in/around landing, ~2 acres = $300.
Planting: labor- $2,566.80 or $142.60/acre, seedlings- $2,769.48 or $153.86/acre, total planting cost of $5,336.28 or $296.46/acre.
Brush saw release: completed 8/5/21, in partnership with The Nature Conservancy, $0.00 cost to State. For reference average cost of brush saw release on state land in 2020 was $167/acre.
Total regeneration costs: $5,636.28 or $313.12/acre.
Other notes
This prescription was a compromise through coordination with MN DNR Divisions of Wildlife and Ecological and Water Resources.
This case study will continue to be updated as further treatments are completed until site is free-to-grow.
For another similar prescription see: Regenerating Blueberry Hill natural origin red pine using a mix of artificial and natural regeneration (MN DNR)
Climate Adaptation Considerations
Increase stand resilience to climate change through increased species diversity.
Summary / lessons learned / additional thoughts
This prescription balanced economic and ecological objectives by using a silvicultural strategy that favored both artificial and natural regeneration of red pine. It used leave tree retention, passive site prep that relied on timber harvest operations, advance regeneration, and variable density planting to achieve the desired results. Early results indicate that compositionally this stand is on track to the specified desired future condition, but future tending and monitoring will be needed to ensure the long-term success of the prescription.
When managing similar stands in the future with the similar objectives it would be more cost effective and reduce planting supervision efforts to designate areas needing variable density and include this type of project on our regular statewide planting contracts, instead of spending several days of planting with a local contractor.
Observations have also shown that relying solely on full tree logging for site prep during dry, non-frozen conditions results in a wide range of mineral soil exposure and competition control across the site, which in itself creates variable planting densities along with varying survival of seedlings..
This case study was reviewed by MN DNR Silviculture Program Staff Mike Reinikainen. Case study submitted on 08/19/2022.