Case Study Name (Landowner)

Fuels Reduction Thinning in Multi-Aged Red Pine (UMN-CFC)

Stand Information
State or Province: 
Minnesota
Nearest city or town: 
Cloquet
Describe the location: 
University of Minnesota Cloquet Forestry Center, E1/2, NW1/4, Sec. 29, T49N – R17W
Landowner: 
University of Minnesota
Cover-type: 
Pine
MN ECS Native Plant Community System: 
Fire Dependent
Plant community or habitat classification and growth stage: 
FDn33a
Forest Health Threats: 
Deer
Other forest health threats
Estimated year of stand origin: 
1778
Additional information about stand origin: 
This is a multi-aged stand; older trees with fire scars suggest seven surface fires between 1850 and 1909, strong recruitment followed both fires and fire-suppression
Silviculture System: 
Other Silviculture System
Brief silvicultural objective: 
To lower stand density in a spatially heterogeneous fashion, reduce fuel-loading in a mature stand by disconnecting foliage between the canopy and sub-canopy, and increase aesthetic appeal of a multi-aged red pine stand. The target structural condition is intended to mimic a historical woodland that would have been maintained by a high-frequency (~every ten years) surface-fire regime.
Soils: 
Omega loamy sand (0-2% slope).
Stand area: 
13 acres
Treatment area: 
13 acres
Overview

This silvicultural prescription was designed for a stand at the Cloquet Forestry Center (CFC) that is adjacent to the main entrance and just to the east and south of the primary buildings and grounds area (see Supplemental Content [SC] Figure 4). The stand is split into two blocks, each around seven acres, separated by University Road. The stand location drove us to develop a prescription with a primary goal of reducing the likelihood of an un-suppressible crown fire with high-intensity behavior and subsequent high severity effects on the stand and structures. 

Silviculture Objective(s)

To conduct a thinning of canopy trees and clearing of the understory to lower stand density and aerial fuels and to disconnect canopy and understory strata. Due to its proximity to the CFC buildings and grounds, the thinning aims to reduce wildfire risk to CFC infrastructure while enhancing forest aesthetics in an area with high visitor use. With this goal in mind, the primary objectives were to 1) reduce overall stand density, 2) reduce the connection of understory and overstory biomass while 3) enhancing forest aesthetics and 4) increasing available growing space to all size classes.

Pre-treatment stand description and condition
Stand establishment and management history: 

General stand history

Increment core and cross-section analyses suggest the oldest trees germinated around 1778. Many of these older individuals display fire scars that demonstrate a pre-European settlement surface fire regime with a return interval of approximately every ten to fifteen years; large diameter, gnarled branches in their lower canopy also indicate a history of a relatively open, low-density canopy conditions throughout period of stand development. The last fire in the scar record occurred in 1894, shortly before the University of Minnesota took over ownership and management of the land in 1909. Historical records indicate three different merchantable harvests in 1927, 1940, and 1951 to, primarily, remove jack pine and promote red pine crop trees (See “Previous Harvests” below). No treatments occurred after 1951. As such, additional recruitment of red pine, balsam fir, spruce, and paper birch increased the overall stand density and connected the biomass between understory and canopy strata via ladder fuels.

Previous harvests: 

Cloquet Forestry Center records indicate the following three merchantable harvest entries occurred within the stand boundaries.

- A 1927 harvest which removed selected mature timber, primarily jack pine with some red pine, from the eastern tract. 

- A 1940 clear cut of mature jack pine (other species not harvested) on the southern half of the western tract south of nursery road and the entire eastern tract. 

- A 1951 harvest with a prescription of “cut as marked” to favor potential red pine crop trees. Species removed included red pine, white pine, jack pine, and aspen. 

Research

Several research projects have occurred within the stand boundary, only one of which influenced this prescription:

A 2015-present study titled, “Impact of future changes in winter conditions on the environment below the snowpack.” Principle investigators are Jonathan Pauli and Benjamin Zuckerberg (University of Wisconsin – Madison). A 30 foot no-cut-zone was maintained around this project area. The total area impacted was roughly 1/10th of an acre and serves as an example of pre-harvest stand conditions. 

General stand history

Increment core and cross-section analysies suggest the oldest trees germinated around 1778. Many of these older individuals display fire scars that demonstrate a pre-European settlement surface fire regime with a return interval of approximately every ten to fifteen years; large diameter, gnarled branches in their lower canopy also indicate a history of a relatively open, low-density canopy conditions throughout period of stand development. The last fire in the scar record occurred in 1894, shortly before the University of Minnesota took over ownership and management of the land in 1909. Historical records indicate three different merchantable harvests in 1927, 1940, and 1951 to, primarily, remove jack pine and promote red pine crop trees (See “Previous Harvests” below). No treatments occurred after 1951. As such, additional recruitment of red pine, balsam fir, spruce, and paper birch increased the overall stand density and connected the biomass between understory and canopy strata via ladder fuels.

Previous harvests:

Cloquet Forestry Center records indicate the following three merchantable harvest entries occurred within the stand boundaries.

-          A 1927 harvest which removed selected mature timber, primarily jack pine with some red pine, from the eastern tract.

-          A 1940 clear cut of mature jack pine (other species not harvested) on the southern half of the western tract south of nursery road and the entire eastern tract.

-          A 1951 harvest with a prescription of “cut as marked” to favor potential red pine crop trees. Species removed included red pine, white pine, jack pine, and aspen.

 

Research

Several research projects have occurred within the stand boundary, only one of which influenced this prescription:

A 2015-present study titled, “Impact of future changes in winter conditions on the environment below the snowpack.” Principle investigators are Jonathan Pauli and Benjamin Zuckerberg (University of Wisconsin – Madison). A 30 foot no-cut-zone was maintained around this project area. The total area impacted was roughly 1/10th of an acre and serves as an example of pre-harvest stand conditions.

Pre-treatment species composition: 

The overstory of the stand had an average basal area (BA) of 191 ft2/ac (CV = 32%). Red pine made up 84% of average BA (see SC Fig. 1); other species included white pine (7% of average BA), spruce (4% of BA), balsam fir (2% of BA), paper birch (1% of BA) and aspen (1% of BA). Advanced regeneration was minimal and included white pine, balsam fir, spruce and some birch. Siberian crab apple regeneration was abundant in an area near the northern boundary of the western tract. There were a few small diameter hardwood species present, including red oak, basswood, and black locust, near the western edge of the eastern tract; these are likely stump sprouts or grown from seed from individuals planted in a 1914 attempt to grow various tree species as part of an arboretum-style display.

Pre-treatment growth and stocking: 

The stand is high-density, dominated by red pine in a wide range of diameter and, likely, age classes. Red pine diameter at breast height ranges from eight to over 24 inches with an average around 18 inches. The growth stage is multi-aged and could potentially be considered old-growth because some individuals are well over 120 years old (see http://www.dnr.state.mn.us/forests_types/oldgrowth/description.html). 

Pre-treatment forest health issues: 

Sirococcus is likely present in the canopy. One pocket, roughly 0.25 ac, of mature red pine displayed thinning crowns with only a year or two of needles; these were targeted for harvest. Mature white pine crowns appear to have some instances of white pine blister rust and/or porcupine damage.

The high stand density and understory-composition, including a plethora of balsam fir ladder fuels, was creating two forest health issues. 1) Xerophilic ground flora, such as blueberry, wintergreen, raspberry, and bush honeysuckle, were being suppressed by the low-light conditions and high humidity causing a reduced likelihood of continuing to operate as a fire dependent community; there is a high likelihood that xerophytic soil microflora and fungal communities have also been shifted towards more mesophilic community members. 2) Increased likelihood of high-intensity and high-severity fire outside the historical range of variation.

Landowner objectives/situation: 

As the University of Minnesota teaching and experimental forest, our primary objectives are to promote educational, research, and outreach opportunities by maintaining a diversity of cover types and growth stages, quality wildlife habitat, water and soil quality, and the historic and cultural resources across the property. To learn more see our most recent decadal forest management plan: https://z.umn.edu/CFC_ManagementPlan2015.

Silviculture Prescription

The structural goals of the stand included creating a spatially heterogeneous arrangement of canopy trees with a range of diameters and, likely, ages. The targeted residual basal area was around 80-90 ft 2/acre with a target spacing of about 25-40 feet between trees. Reserve trees were selected to retain a two-peak diameter distribution with peaks around ten and 24 inches. Large trees in the >24” diameter class were retained to promote visual appeal while red and white pine in the 8-11” diameter class were retained to serve as future crop trees, likely merchantable in 10-15 years. Snags and coarse woody debris, characteristic of old-growth stands, were kept for visual interest and wildlife habitat. The understory and mid-story was mostly cleared to discourage ladder fuels; some pockets of white pine and/or paper birch advanced regeneration were kept as future canopy replacement species.

 In the short-term (~30 years), a canopy of red pine and some white pine (<10% basal area) is desired. In the longer-term (>30 years) a mixed canopy of red pine, white pine, and paper birch is desired; natural regeneration, and some artificial regeneration, of paper birch, white pine, and red pine in the understory will be permitted to promote this future canopy condition.

 The harvest guidelines specified a spring/summer harvest, completed by the end of 2016, and required full-tree harvesting and chipping of tops and any red pine slash of three inches diameter or larger. Full-tree skidding and growing season harvest was specified in order to passively scarify the ground to encourage pockets of white pine and paper birch natural regeneration; though this is a lower-priority objective. Chipping of tops and >3” diameter red pine slash was specified to reduce the likelihood of a pine bark beetle outbreak.

What actually happened during the treatment

Bell Timber, Inc. purchased the sale and contracted operations with Berthiaume Logging, Inc. Berthiaume Logging used conventional, full-tree skidding techniques and chipped a majority of the tops and slash. Logging operations began May 31, 2016 and ended June 17, 2016, a total of about 14 working days. Operations went as planned. Due to the aesthetic goals, biomass from delimbed trees was chipped and hauled away rather than returned to the harvest area.

Volume harvested

In total, 415.61 cords were harvested during operations. Total income generated by the sale was $1,489.11 per acre. See Table 1 for a breakdown of volume harvested per species and product.

Table 1. Total volume by species and product harvested during operation

Species

Product

Vol. Harvested (cords)

Red pine

Poles/House Logs

63.38

Red pine

Sawlogs/bolts

234.70

Jack pine

Bolts

10.48

Spruce

Bolts

12.05

Spruce

Pulp

23.52

Softwood

Pulp

38.03

Aspen

Pulp

24.93

Birch

Pulp

8.52

Total

 

415.61

Bell Timber, Inc. purchased the sale and contracted operations with Berthiaume Logging, Inc. Berthiaume Logging used conventional, full-tree skidding techniques and chipped a majority of the tops and slash. Logging operations began May 31, 2016 and ended June 17, 2016, a total of about 14 working days. Operations went as planned. Due to the aesthetic goals, biomass from delimbed trees was chipped and hauled away rather than returned to the harvest area.

 

Volume harvested

In total, 415.61 cords were harvested during operations. Total income generated by the sale was $1,489.11 per acre. See Table 1 for a breakdown of volume harvested per species and product.

Post-treatment assessment

The average stand BA after the harvest was 113 ft2/ac (CV = 64%). The BA is a little bit higher than we were hoping for but the stand feels nice and open anyway. The post-harvest BA CV was 100% higher than the pre-sale BA CV, suggesting a good increase of heterogeneity. The objective of creating a two-peaked diameter distribution in the residual standing timber appears to have not been effectively met (see SC Fig. 2). However, viewing the diameter distribution with trees per acre as the dependent variable (vertical axis, SC Fig. 3) shows slight peaks in the 10-11” and 26” diameter classes.

Plans for future treatments

Management
We will be looking to maintain the structure of this stand by reintroducing a high-frequency surface fire regime and follow-up merchantable harvest treatments. The first burn is planned for 2020; pre-and post-burn fuels and vegetation monitoring will be conducted. The next timber sale could potentially happen around 2032. Adaptive management will ensue and be dependent on surface fire and timber sale effects on understory vegetation and new or altered management objectives. Inevitably, we will want to target recruiting a new cohort of pine (both red and white). One way we could do this potentially by allowing a fire-free interval of 20 years once monitoring demonstrates a strong pulse of pine regeneration.
Research
Five replications of a two-plot set up of white pine seedlings were planted in May 2017 (second post-harvest growing season) as part of a deer exclosure research study titled, “Northern Minnesota deer browse exclosure size and shape study.” The principle investigators are Howard Hoganson and Michael Carson (both of the University of Minnesota) and the local site contact is Kyle Gill. Each replication has one plot that has 16 2-2 white pine seedlings within a 100’ perimeter by five feet tall fenced deer exclosure and another plot with nine 2-2 white pine seedlings planted within a 50’ perimeter by five feet tall deer exclosure. T-posts support the concrete mesh fence. The silvicultural aim of these groups is that at least one or two seedlings survive to grow into the canopy. As of 2019, deer had not impacted any of seedlings.

Costs and economic considerations

In total, 415.61 cords were harvested during operations. Total income generated by the sale was $1,489.11 per acre. See Table 1 for a breakdown of volume harvested per species and product. The trees to be removed during the operation were individually marked by two foresters from Bell Timber, Inc. (the purchaser) and reviewed by the seller. In total, marking took roughly one day for the two foresters.

Climate Adaptation Considerations

Climate adaptations did not influence this prescription.

Summary / lessons learned / additional thoughts

All aspects of operation went as planned. Though fuels-specific monitoring has not yet been conducted, evidence suggests that if a fire were to get started near this stand, there is a high likelihood that it would stay in the understory and not be able to reach the canopy. Anecdotal ground vegetation monitoring suggests that opening up the canopy encouraged renewal of raspberry, blueberry, and beaked hazelnut stems and fruiting as well as germination of single-stem paper birch, some red and white pine, and tamarack.

Having aesthetic quality as one of the top objectives was interesting to consider. This was achieved by maintaining many of the old, gnarly red and white pines, reducing the basal area and mid and understory vegetation to open up sightlines through the stand, as well as increasing the heterogeneity of spatial arrangement of residual trees (the coefficient of variation [CV] around the mean basal area increased from 32% to 64%).

Supplemental content ("appendices")
PDF icon Download supplementalcontent_fuelsreductionthinningmultiagedredpine_20190816.pdf (4.52 MB)
Photographs
A view through the spatially heterogeneously arranged mature residual trees and minimal understory biomass.A view through the spatially heterogeneously arranged mature residual trees and aster and goldenrod making up a majority of understory biomass.A view of the stand as the operation started with relatively high-density overstory and understory trees and shrubs.A view towards the eastern tract of the prescription area from the main entrance to the Cloquet Forestry Center.
Keywords
red pine
Cloquet Forestry Center
variable density thinning
firewise
fire protection
white pine
Biography
Name: 
Kyle Gill
Organization: 
University of Minnesota
Kyle Gill

As the CFC’s forest manager, Kyle is interested in stand development and dynamics as well as managing forested stands and landscapes as complex adaptive systems. He enjoys managing a research forest because of the freedom to consider both art and science in silvicultural prescriptions and pushing the boundaries of how we interact with forest communities.

Title: 
Forest Manager and Research Coordinator
Address: 
175 University Road
Cloquet , MN 55720 ,
Phone Number: 
(218) 726-6412
Email: 
kggill@umn.edu