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A Comparison of A Comparison of Phragmites Phragmites australisaustralis Control Measures in Control Measures in Wisconsin Coastal WetlandsWisconsin Coastal Wetlands

Devany PlentovichDevany Plentovich

29 September 200829 September 2008

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Introduction

• Phragmites australis is out-competing common and rare native plants on Lake Michigan’s beaches & coastal wetlands.

• Current herbicide control methods are expensive and can harm rare and sensitive plant species.

• Follow-up monitoring is needed. – Are control methods effective?– Which treatments are most effective?– Do ecological benefits outweigh the costs?

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Objectives

• Do control methods eradicate Phragmites?

• Which control method is most effective?

• What species of plants are present after treatment?– Are they native wetland species?

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Study Sites

1. Long Tail Point

2. Ridges Sanctuary

3. Peshtigo Harbor

4. Seagull Bar

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3

2

1

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Study Design

• Treatment categories

N = 1-5 plots

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Site Treatment Plots Sub-plots

Long Tail Point Control 5 10Spray Only 5 10Spray/Mow 2 10Spray/Burn 5 10

Ridges Sanctuary Control 5 10Spray Only 5 10Spray/Mow 5 10

Peshtigo Harbor Control 3 10Spray Only 4 10Spray/Mow 1 10Spray/Burn 5 10

Seagull Bar Control 5 10Spray Only 3 10Spray/Mow 5 10Spray/Burn 5 10

Total 63 630

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Methods

• Variables– Species richness – % cover (all species)– litter depth– Phragmites height

• August 2007

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Results

• Treatment Effectiveness

– 89% of the treatment plots contained Phragmites.

– None of the treatment techniques were effective at eradicating Phragmites after one treatment.

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0

10

20

30

40

50

60

% P

hra

gm

ites

au

stra

lis

Control

Spray

Spray/Burn

Spray/Mow

ResultsWhich control treatment was most effective at controlling Phragmites australis?

• All treatment methods significantly reduced % P. australis (ANOVA, p < 0.001)

• The three control methods were not significantly different from each other (Tukey HSD, p > 0.05)

• All sites showed the same pattern of P. australis reduction, with the exception of Ridges.

A

BB B

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Results

0

50

100

150

200

250

Ave

rag

e P

hra

gm

ites

Hei

gh

t

Control

Herbicide

Herbicide/Burn

Herbicide/Mow

B

CB

A

Which control treatment was most effective at controlling Phragmites australis?

Herbicide/mow significantly reduced height over other treatments and control (ANOVA, p < 0.001)

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ResultsDoes species richness differ among treatments?

Herbicide/mow had significantly higher species richness than other treatments and control (ANOVA, p < 0.001)

AA

CB

0

2

4

6

8

10

12

Sp

ecie

s R

ich

nes

s

Control

Spray

Spray/Burn

Spray/Mow

AB AB

C

12

0

2

4

6

8

10

12

14

Control Spray Spray/Mow Spray/Burn

Sp

ecie

s R

ich

nes

s

ResultsEffects of treatment on species richness

Species richness in herbicide/burn was significantly higher at Long Tail.

Treatments at this site were applied in 2005 and 2006; others were treated in 2007.

0

2

4

6

8

10

12

Sp

ecie

s R

ich

nes

s

Long Tail

Ridges

Peshtigo

Seagull Bar

B

A

B B

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Results

0

10

20

30

40

50

60

% C

ov

er

of

Na

tiv

e S

pe

cie

s

Control

Herbicide

Herbicide/Burn

Herbicide/Mow

BB

C

A

Effects of treatment on Mean % Cover of Native Species

Herbicide/burn had significantly higher species richness than other treatments and control (ANOVA, p < 0.001)

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0

10

20

30

40

50

60

% C

ov

er

of

Na

tiv

e S

pe

cie

s

Long Tail

Ridges

Peshtigo

Seagull Bar

B

C

B

A

0

10

20

30

40

50

60

70

80

0 1 2 3 4

% C

ov

er

of

Na

tiv

e S

pe

cie

s

C H H/B H/M

ResultsEffects of treatment on Mean % Cover of Native Species

% Cover of Native Species in herbicide/burn was significantly higher at Longtail.

All treatments show the same patterns with the exception of Peshtigo.

Herbicide/Burn showed significant higher % cover of native species. The majority of the cover was Calamagrostis canadensis.

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Review of Results

VariableHerbicide

OnlyHerbicide/

BurnHerbicide/

Mow

% P. australis      

Average P. australis height      

Species Richness      

% Cover of Native Species      

Green – performed bestYellow – performed acceptably

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What types of plant species were present after Phragmites treatment?

Type Number

Total Species 139*

Native 111

Introduced 15

Invasive 13

* An additional 37 were not identified to the species level

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Campanula aparinoides (7) Carex stricta (7)

Cicuta bulbifera (7) Cirsium muticum (8)

Eleocharis flavescens (8)* Epilobium leptophyllum (8)

Equisetum variegatum (7) Liparis loeselii (7)

Lobelia kalmii (9) Lysimachia thyrsiflora (7)

Parnassia glauca (8) Picea glauca (7)

Pilea fontana (7) Thuja occidentalis (9)

Zizania palustrus (8)

Results

• Wisconsin Floristic Quality Assessment– No significant differences with Floristic Quality Index or

Coefficient of Conservation– Indicated presence of highly desirable wetland plants

What plant species will return after treatment?

* Species of concern

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Conclusions

• Eradication is not feasible with one application of these control methods.

• Adding a secondary treatment improved effectiveness

– Herbicide/mow showed significantly higher species richness (exception Long Tail).

– Herbicide/burn showed significantly higher % cover of native species.

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Conclusions

• Native plant species are present to re-populate treated wetlands.

• Treatment soon after invasion is critical for restoration success.

• Long-term maintenance will be required to maintain native wetland vegetation.

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Recommendations• Monitor Herbicide/mow and

Herbicide/burn treatments for 2-3 years.

• Evaluate Habitat 7 sensitivity for wetland plants.

• Continue to prioritize P. australis treatment for critical habitat.

• Include follow-up herbicide treatment for successive years in funding requests.

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AcknowledgementsProject funding provided by Wisconsin Dept of Agriculture from:

• Lakeshore Natural Resource Partnership• Wisconsin Coastal Management Program

Matching funding provided by:• Department of Agriculture, Trade, & Consumer Protection• University of Wisconsin-Green Bay

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Acknowledgements• Andy Hinickle - Wisconsin Department of Natural Resources• John Huff - Wisconsin Department of Natural Resources• Steve Leonard – Ridges Sanctuary• Mark Martin - Wisconsin Department of Natural Resources• Ursula Petersen – Wisconsin Department of Agriculture, Trade, &

Consumer Protection• Gary VanVreede - US Fish and Wildlife

• Photos by Ridges Sanctuary, Gary VanVreede, Kathryn Corio, Devany Martin

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Acknowledgements

• Hannah Aplin• Laura Bratz• Kathryn Corio• Gary Fewless• Aaron Groves• Jennifer Goyette• Dr. Robert Howe

• Ursula Petersen• Dr. Tara Reed • Juniper Sundance• Gary VanVreede• Claire Waldvogel• Jay Watson• Dr. Amy Wolf

Field Team and Committee Members