Case Study Name (Landowner)

Controlling Sedge and Ironwood to Promote Northern Hardwood Regeneration (Ashland County)

Stand Information
State or Province: 
Wisconsin
Nearest city or town: 
Butternut
Describe the location: 
Sites are located in Compartment 53, Stand 4 on Ashland County Forest, Section 18 T42N R1E.
Landowner: 
Ashland County
Cover-type: 
Northern hardwoods
Plant community or habitat classification and growth stage: 
AOCa: mesic and nutrient medium to rich
Forest Health Threats: 
Invasive plants competing vegetation
Estimated year of stand origin: 
1909
Additional information about stand origin: 
This information was not tracked for this particular stand but stand age is estimated to be between 80 and 110 years
Brief silvicultural objective: 
Manage Pennsylvania sedge and ironwood in order to facilitate northern hardwood regeneration.
Soils: 
Butternut silt loam; Coarse-loamy, isotic, frigid Alfic Oxyaquic Haplorthods.
Stand area: 
127 acres
Treatment area: 
40 acres
Overview

Pennsylvania sedge (Carex pensylvanica) and ironwood (Ostrya virginiana) are present and limiting the regeneration of desired northern harwood species, bringing the future of the stand's northern hardwood covertype classification into doubt. This case study outlines a treatment that is the culmination of two years of trials involving the use of herbicide in managing for competing vegetation. The most effective herbicide application method, and the subject of this case study, was found to be a tank mix of Garlon XTR, Oust and Accord to control a broad spectrum of unwanted plant species. The best sugar maple seedling establishment occurred when the herbicide application coincided with a good seed crop. However, the stand level application used in this treatment is not believed to be as efficient as targeting canopy gaps, groups, or patches in order to promote regeneration establishment.

Silviculture Objective(s)

1. Temporarily eliminate Pennsylvania sedge and other unwanted herbaceous and woody plants that inhibit the establishment of northern hardwood regeneration.
2. Establish sugar maple regeneration from natural seeding.
3. Gain a better understanding of what types of treatments facilitate efficient and effective control.
4. Gain a better understanding of the types of chemicals, rates of application and timing of application for efficient and effective control.

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

This stand was harvested in the summer of 2012 using a cut to length harvester/forwarder. This was a single tree selection harvest w/ 30-60’ canopy gaps on +/- 10% of the stand area. Basal area before harvest was 128 ft2/ac and residual stand basal area was 97ft2/ac. In the fixed plots established for this trial basal area was measured to be 82ft2/ac.

Pre-treatment species composition: 

Table 1: Overstory species composition for stand 53-4 as a percentage of the whole. 

Species Percent
sugar maple 65
basswood 29
ash, yellow birch, red maple 6

Table 2: Pre-treatment regeneration, recorded in 1/100th acre regeneration plots. Regeneration refers to everything less than 5" DBH. 

Tree Species Regen/Acre
sugar maple 560
ironwood 460
basswood 320
black cherry 520
red maple 0
balsam fir 140
white spruce 20
red oak 20
white ash 200
white birch 0
Total Stems/Acre 2240
Pre-treatment growth and stocking: 

Table 3: Diameter distribution for the stand. The average DBH is 13". 

Size Class DBH Range (in) Basal Area (ft2/acre)
pole 5-11 24.5
small saw 10-14 63
medium saw 15-20 9.5
large saw 20+ 0
Pre-treatment forest health issues: 

Pennsylvania sedge and ironwood are limiting northern hardwoods regeneration. 

Silviculture Prescription

Stand level application with skidder & spray tank (2013): 

1. Herbicide application: use a skidder mounted herbicide sprayer to treat +/-40 acres of stand with heavy ground layer of Pennsylvania sedge and ironwood. 
2. Treat site with Garlon XRT (1.5qt/ac) Accord XRT(2.05qt/ac) and Oust (1.03oz/ac). 

What actually happened during the treatment

Stand level application with skidder & spray tank (2013): 

1. Herbicide application August 6th 2013: Used skidder mounted herbicide sprayer to treat +/-40 acres of stand with heavy ground layer of Pennsylvania sedge and ironwood. Other species such as ferns & Rubus spp. also present.
2. Treated site with Garlon XRT (1.5qt/ac) Accord XRT(2.05qt/ac) and Oust (1.03oz/ac). 5 test plots and 2 control plots were established and inventoried to measure composition and abundance of tree/shrub species and percent sedge cover prior to application. Plots are 1/100th acre and are permanently marked with a metal rod plot center and GPS. Application was timed to correspond to a good seed year. Monitoring will be completed for several springs and falls to determine success.

The tractor sprayer used (see figure 5) has a 150 gallon tank, driven by a P.T.O., and could apply herbicide via a boom or 100 foot hose reel. The boom is 12 feet with five nozzles and when fully raised can cover roughly 20 feet. Spray from the hose reel can reach an additional 20-30 feet beyond the 100 foot hose. 

Post-treatment assessment

Table 4: Post-treatment regeneration in the spring of 2014, recorded in 1/100th acre regeneration plots. Regeneration refers to everything less than 5" DBH. 

Tree Species Regen/Acre
sugar maple 2080
ironwood 220
basswood 160
cherry 60
red maple 0
balsam fir 120
white spruce 20
red oak 0
white ash 0
white birch 0
Total Stems/Acre 2660

Table 5: Post-treatment regeneration in the fall of 2014, recorded in 1/100th acre regeneration plots. 

Tree Species Regen/Acre
sugar maple 4800
ironwood 1000
basswood 320
cherry 460
red maple 1080
balsam fir 300
white spruce 20
red oak 0
white ash 400
white birch 20
Total Stems/Acre 8400

Table 6: Post-treatment regeneration in 2019, recorded in 1/100th acre regeneration plots. 

Tree Species Regen/Acre
sugar maple 13380
ironwood 340
basswood 600
cherry 380
red maple 720
balsam fir 650
white spruce 20
red oak 0
white ash 0
white birch 0
Total Stems/Acre 16090
Plans for future treatments

This stand is scheduled for a selection harvest in 2020 but is likely not going to be ready by then. However, the selection harvest will definitely occur in the next 10 years. 

Monitoring will continue in subsequent springs and falls to determine the success of this treatment. 

Costs and economic considerations

The stand level skidder application with Garlon/Accord/Oust is about $125 per acre. This price fluctuates somewhat due to fuel prices and herbicide costs. 

Other notes

This case study was developed with support from the United States Department of Agriculture's National Institute for Food and Agriculture (USDA-NIFA), Renewable Resources Extension Act (RREA). Project #MIN-44-E02, principal investigator Eli Sagor, University of Minnesota.

Summary / lessons learned / additional thoughts

• The most effective herbicide application was a tank mix of Garlon XTR, Oust and Accord to control a broad spectrum of unwanted plant species.
• The best sugar maple seedling establishment occurred when the herbicide application coincided with a good seed crop.
• Sites selected for application need to be thoroughly monitored prior to application to ensure that regeneration is not establishing on its own. Preferably late spring early summer or during leaf color change in fall in first 1-3 years after harvest.
• Sugar maple seedlings will establish in the treated areas immediately following snow melt in the spring.
• Newly established seedlings are very susceptible to moisture stress after germination.
• Stand level application probably not the best method. Better to focus on canopy gaps, groups or patches.
• Stand level application resulted in minor ground surface erosion in areas with minor slopes.
• Stand level application allowed hemp nettle & Canada thistle to establish in treated area after second year. At year five they were much less abundant than year two.
• Oust Considerations - Between fall 2014 & spring 2019 a decline in ironwood, black cherry, ash and red maple seedlings occurred. Other than casual observations the stand was not inventoried 2015-2018. This period of time saw average to above average precipitation so moisture stress is unlikely. It was also observed in 2019 that most hard maple seedlings were much smaller than expected and appeared to be only 2 years old. It is suspected that the pre-emergent activity of Oust may have contributed to some seedling mortality while it remained active in the soil. Rich Ludholz, Ludholz North Star Acres Tree Nursery has had similar issues with failure of nursery stock after seed beds were treated with Oust in the prior year(s). The length of time Oust will remain active in the soil will depend on soil characteristics, environmental factors, weed size/intensity and application rate. While it is suspected that Oust may have contributed to some seedling loss, the use of it did not prevent adequate regeneration from establishing, but perhaps delayed it an additional 2-3 years from the application date, while at the same time controlling sedge and ironwood for 2-3 years.
• From 2014-2019 canopy closure was 13% whereas plot basal area only changed 2.4% (2sqft/ac).
• Sedge is a player in regeneration. Other factors are less apparent but appear to be very significant contributors to a sedge / regen problem, including soil moisture, seed production, timing of harvest, herbivory, canopy closure, earth worms, aspect, and tree ages.

Photographs
Figure 1: Before stand level treatment, which was carried out with a skidder and spray tank in 2013.Figure 2: After stand level treatment, which was carried out with a skidder and spray tank in 2013.Figure 3: fixed 1/100th acre plot within the stand-level application area featuring roughly 37,000 sugar maple seedlings per acre.Figure 4: Untreated control plot in 2019.Figure 5: Tractor sprayer with 150 gallon tank, P.T.O. driven. Boom is 12 feet with 5 nozzles and when fully raised can cover about 20 feet.
Keywords
silv-FH
SilvFH
NIFA
Pennsylvania sedge
Sedge
northern hardwood
herbicide
selection
Ashland county
Garlon
Oust
Accord
Biography
Name: 
Matt Schultz
Organization: 
Ashland County Forestry and Recreation Dept
Title: 
Assistant Forest Administrator
Phone Number: 
(715) 769-3777
Email: 
ashlandcountyforest@outlook.com
Name: 
Lane Moser (Editor)
Organization: 
University of Minnesota Department of Forest Resources
Lane Moser in Oregon
Title: 
Graduate Student
Email: 
rlmoser2@gmail.com
Citation: 

Schultz, M. 2019. Controlling Sedge and Ironwood to Promote Northern Hardwood Regeneration (Ashland County). Great Lakes Silviculture Library. University of Minnesota. Cloquet, MN. Available: https://silvlib.cfans.umn.edu/content/controlling-sedge-and-ironwood-pro...