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

Stand Information

2017 Aerial photo showing shelterwood harvests

State or Province:

Minnesota

Nearest city or town:

Malmo

Describe the location:

Aitkin County Tax Forfeited Lands

Landowner:

Aitkin County

Cover-type:

Northern hardwoods

MN ECS Native Plant Community System:

Mesic Hardwood

Plant community or habitat classification and growth stage:

MHn35

Forest Health Threats:

N/A

Estimated year of stand origin:

1927

Site Index:

Silviculture System:

Shelterwood

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:

Fall harvest vs. winter harvest
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, fall harvest
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 1^st 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 1^st 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")

Download 12732aerial.jpg (544.56 KB)

Download 12722aerial.jpg (538.56 KB)

Download stand_info.jpg (140.35 KB)

Photographs

Keywords

shelterwood

oak

basswood

birch

Biography

Name:

Bob Kangas

Organization:

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

Aitkin , MN 56431

Phone Number:

(218) 927-7364

Email:

acld@co.aitkin.mn.us

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Case Study Name (Landowner)

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