Sawyer Swamp Hardwood Conversion Trial (WI DNR)

State or Province
Nearest city or town
Describe the location
Uhrenholdt Memorial State Forest
Wisconsin DNR
Cover type
Forest health threats
Adaptive silviculture options
Silviculture system
Estimated year of stand origin
Additional information about stand origin
Site planted in 2010.
Brief silvicultural objective
To investigate relative performance of species with potential to replace black ash threatened by emerald ash borer.
Site preparation method
Soil texture
Soil details
Seelyeville and Markey. The soil profile of this site exhibited a shallow organic muck layer over sandy outwash/loam. This soil profile may be conducive to limiting flooding at the site since no swamping was observed over the few years of observation.
Stand area
1 acre
Treatment area
1 acre

46.116551, -91.3568


The goal of this project is to find and demonstrate viable management practices to use for conversion of black ash dominated lowlands to other timber species in the event of an Emerald Ash Borer attack. Currently, little has been done on the sites because of failed attempts in regeneration and flooding potential. In the Great Lakes states, there is an urgent need to explore options in converting black ash dominated lowland to other tree species to avoid losing forests.

Pre-treatment stand description and condition

Stand establishment and management history: 

The site (approximately 1 acre) was previously tag alder and black ash (habitat type FnAbArOn). 
The soil profile of this site exhibited a shallow organic muck layer over sandy outwash/loam. This soil profile may be conducive to limiting flooding at the site since no swamping was observed over the few years of observation.

Figure 1: View of adjacent stand similar to pre-treatment condition

Silviculture Prescription

Project Elements and Projected Costs:
  1. The site (approximately 1 acre) was previously tag alder and black ash (habitat type FnAbArOn). It was mowed using a fecon mower during the winter of 2009-10. (estimated cost for 8 hours- $1500)

  2. After mowing, a plastic mesh fence was constructed around the site to limit or eliminate deer and rabbit browsing.  One of the four permanent sample plots will be outside the fence.  (estimated cost for 850’ of 7’ tall fence -  $2500)
  3. An herbicide application was done in June of 2010 to kill sprouting, herbaceous and grass competition.  (estimated cost - $160)
  4. Hand planted containerized and bare root seedlings of tamarack, black spruce, and red maple in late August or early September 2010.  (estimated cost for labor and travel only (seedlings provided by nursery) - $350)
  5. Established four fixed permanent, 1/50th acre plots to record success of planted seedlings and natural seeding and to document any competition.  (estimated cost $100)
  6. Direct seed site with black spruce and tamarack in late September 2010.  (estimated cost $100)
  7. Evaluate results in late July 2011.  Data such as survival, height growth, browse effects and other factors will be measured.  Data will also be compared to other conversion trials established (Phillips School Forest planting in 2009; future trials on state lands established in 2011 if funding is available; future trials on county lands established in the future).
  8. Evaluate results in late July 2012.  Remove fence after evaluation.
  9. Additional plots in other locations will be needed to validate results learned here and will be established in coming years if funding is available.

Figure 2: Deer fence and planted seedlings, August 2015

What actually happened during the treatment

  • 12/07/2009: Site approximately 1 acre in size (square/rectangular in shape; wet area to the south of Stand 1 (PW 15+)) selected and cleared using Fecon (140HP). The Fecon was down for several weeks after this due to problems with the starter.
  • 07/20/2010: Sprayed with herbicide mix of Arsenal, Glystar and Chameleon.  [80oz of Arsenal Powerline (26.7% isopropylamine salt of imazapyr); 64 oz of Glystar Plus(41% glyphosate); 8 oz of Chameleon (non-ionic spreader sticker – Alkyl polyoxyehylene ethers, polymerized resins and fatty acids)].
  • 07/27/2010: Installation of 8ft plastic fence/steel fence posts around perimeter of site.  Material cost for fence was $1186.51, plus about 48 person hours to install.
  • Hand sprayed parts of the site with Glystar Plus again to kill areas that were missed during the first application. 9-21-10.  Still has some competition that looks to be alive.
  • 9/23/10 received 2.5-3 inches of rain.  Now has standing water on the NW corner of the site.
  • Laid out and hand planted a variety of seedlings 9-27/28-2010 in rows running north to south – about 80 person hours to plant total.  Flags placed every 4’ between tree rows placed 2’x2’. Planted tamarack 2-0 bare root, tamarack container 6mo from Toumey, black spruce bare root and container, white pine 3-0 bare root, white spruce 3-0 bare root, black ash 3-0 bare root, yellow birch 2-0 bare root, red maple 2-0 bare root, trembling aspen container 5 mo from Hayward, hemlock 3-0 bare root, will plant balsam 3-0 bare root Minnesota next spring.  Site was extremely rocky and root covered making planting large seedlings difficult.  Planted through water standing on north side which will probably kill those seedlings.  Planting quality on the larger seedlings was questionable.  Row by row inventory of planted seedlings was taken 10-5-10 by Dave and Gordy recording heights of every 6th seedlings and if it was on a dry, wet, or underwater site.  Less water was evident on the site compared to the day of planting.

Figure 3: Swamp hardwood conversion site groundstory moss

Post-treatment assessment

Post-treatment assessment of seedling performance (as of August 2014):

Species Survival % Average Height (ft.) Height Range (ft.)
Red Maple 47% 3.1 1-6
Yellow Birch 37% 3.9 2-6
Trembling Aspen 37% 1 1-2
Black Ash 77% 2.9 2-5
White Pine 83% 3.3 2-5
Balsam Fir 0% - -
Tamarack (Container) 92% 5.9 2-10
Tamarack (Bare Root) 90% 5.3 2-8
Black Spruce (Container) 73% 3.7 1-6.5
Black Spruce (Bare Root) 66% 3.4 1-5.5
White Spruce 58% 2.9 1.5-4.5
Hemlock 35% 1.7 1-3


Figure 4: Four-year planted seedling performance data

Figure 5: Planted seedlings of white pine, tamarack, and white spruce, August 2015

Figure 6: Swamp hardwoods conversion site showing planted seedlings, August 2015

Costs and economic considerations

See cost information in "Silviculture Prescription" and "What actually happened during the treatment" above.

Other notes

Survival and growth of the conifers was superior to that of the deciduous tree species. The fence had been knocked down prior to the visit in 2014. Deer browsing was observed and had more of an effect on the deciduous seedlings. Sedges were dominant throughout the site, especially in the wetter areas. Tree survival and growth was better on the dryer areas. Natural seeding of red maple and white pine were present throughout the site. 

Summary / lessons learned / additional thoughts

This writeup draws heavily from the Wisconsin Silviculture Trials site, at .