Case Study Name (Landowner)

Comparing Fall vs. Winter Shelterwood Harvests (Aitkin County MN)

Stand Information
State or Province: 
Minnesota
Nearest city or town: 
Malmo
Landowner: 
Aitkin County
Cover-type: 
MN ECS Native Plant Community System: 
Plant community or habitat classification and growth stage: 
MHn35
Forest Health Threats: 
Estimated year of stand origin: 
1927
Site Index: 
63
Silviculture System: 
Brief silvicultural objective: 
Two step shelterwood harvest to encourage red oak, basswood, birch regeneration.
Soils: 
Site 1: Bushville Loamy Fine Sand and Pomroy Loamy Fine Sand Site 2: Milaca Fine Sandy Loam
Stand area: 
51 acres
Treatment area: 
51 acres
Overview

Compare two northern hardwood shelterwood harvests that were logged the same year but with different variables:

  1. Fall harvest vs. winter harvest
  2. Loamy Fine Sand vs. Fine Sandy Loam
Silviculture Objective(s)

Take two northern hardwood stand dominated by maple and birch and convert them to an oak, birch and basswood stand through a two step shelterwood system.

Pre-treatment stand description and condition
Pre-treatment growth and stocking: 
Site 1, loamy fine sand Site 2, fine sandy loam
Initial BA --> Final BA Initial BA --> Final BA
Acer sp. 59 --> 12 38 --> 5
Quercus rubra 17 --> 12 22 --> 17
Betula papyrifera 12 --> 4 31 --> 13
Tilia americana 6 --> 5 12 --> 6
Populus sp. 2 --> 0 5 --> 0
Fraxinus nigra 2 --> 2 1 --> 1
Betula allaghaniensis 5 --> 5 0 --> 0
Total Basal Area 103 --> 40 109 --> 42
Silviculture Prescription

Harvest the forest stand, retaining between 35-49 sq. ft. of residual basal area. This strategy is used to regenerate the stand to mid-tolerant and somewhat intolerant species such as oak, basswood, paper birch and yellow birch under a uniform shelterwood system. Trees are selected for retention during the establishment (first) harvest to retain the best quality, biggest diameter, and preferred species (e.g. oak, birch, and basswood).

Regeneration will then be released by overstory removal when it reaches the desired size and stocking. This effectively converts the stand to a more desirable forest type comprised of the species reserved from harvest. Retention of snags, den trees and the multiple canopy layers should enhance wildlife habitat. Applying BMPs protects water resources potentially impacted by harvest operations.

What actually happened during the treatment

Site 1 (loamy fine sand)

First Harvest

Fall 2008

Final Harvest

Winter 2016-17

Logging Conditions 2008

Dry, snow covered but not frozen

Logging system

Full Tree

Acorn Crop

Excellent in 2008

Site 2 (fine sandy loam)

First Harvest

Winter 2008-09, 33 Acres

Final Harvest

Winter 2016-17

Logging Conditions 2008

Snow covered but not frozen

Logging system

Conventional in 2008-09

Acorn Crop

Excellent in 2008

Post-treatment assessment

Regeneration sampling:  numbers of stems per acre sampled before the overstory removal in 2010 and 2013, and after overstory removal in 2017 including number of stems greater than 3’ in height.  Maple was not counted but was present in large numbers.

Site 1

1st  Harvest -Fall 2008

Loamy Fine Sand

2010

2013

2017

>3’

Avg. Height

Acer sp.

Not counted

Not counted

3,437

1,625

2’

Quercus rubra

1,100

1,386

2,316

1,800

3-5’

Betula sp.

3,600

2,900

4,437

3,250

3-5’

Tilia americana

25

22

875

688

2-3’

Fraxinus nigra

30

0

0

0

2-3’

Total Trees

4,755

4,308

11,065

7,363

 

Site 2

1st  Harvest -Winter 2008

Fine Sandy Loam

2010

2013

2017

>3’

Avg. Height

Acer sp.

Not counted

Not counted

4,636

2,272

2-3’

Quercus rubra

860

2,000

772

409

2-3’

Betula sp.

640

1,363

3,590

2,227

3-4’

Tilia americana

600

180

909

228

2-3’

Fraxinus nigra

136

0

590

318

2’

Total Trees

2,236

3,543

10,497

5,454

 

Summary / lessons learned / additional thoughts
  • Both silviculture prescriptions were a success
  • Site 1 had better regeneration because of a combination of fall logging and lighter soils.
  • In 2017, Oak (Quercus) and birch (Betula) had significant height advantage over maple (Acer).  The height difference was more pronounced in Site 1, the loamy fine sand.
  • For unknown reasons, height growth of oak and birch were better on Site 1, loamy fine sand.
  • Winter harvest can produce adequate oak and birch regeneration given a good acorn and seed crop.
  • Shelterwood harvest is an effective method to regenerate oak and birch under a variety of scenarios.
Supplemental content ("appendices")
Photographs
Regeneration at site 1.Regeneration at site 2.
Keywords
Biography
Name: 
Bob Kangas
Organization: 
Aitkin County Land Dept
Aitkin County Land Dept.

Aitkin County, through its Land Department, is responsible for the management of more than 222,000 acres of tax forfeited land. The County has a long tradition of being a sound steward of this resource providing timber and fiber for industry, offering recreational opportunities for residents and visitors, and sustaining the ecological integrity of the land and its forests.

Title: 
Forester
Address: 
209 2nd St. NW Room 206
56431 Aitkin , MN
Phone Number: 
(218) 927-7364