Effects of common reed (Phragmites australis) invasion on carbon

transformations in a Great Lakes coastal marsh

Shawn Duke

Background: -Wetland invasion by Phragmites australis -Marsh carbon pathways -Environmental factors -Plant chemistry Questions: Three experiments -Litter decomposition -Water levels -Plant leachates Conclusions: -Carbon budget

Erie Canal - 1825 • Original genetic

diversity from New England and Canada

• Landing points in Lake Erie

• Seed viability 1 – 20%

Site Location

J Kirk

Detroit River International Wildlife Refuge

May 8 1985 SEMCOG

1985, 1992, 1998 Completely submerged – No emergents

2000 Level slightly lower – Diverse emergent/floating

2005 Typha dominant – Patchy Phragmites

2009 Phragmites dominant in central marsh

Pre-Invaded Wetlands

Study Site ca 1800

Emergent Marsh -water plantain -sedges -spike-rushes -pond-lilies -pickerel weed -arrowheads -bulrushes -cattails

Wet Prairie -bluejoint grass -cordgrass -sedges

MNFI

Plant Diversity

USFWS

Typha Phragmites

Biodiversity + -

Habitat + -

Invasive Control

MI Sea Grant

Global Carbon Cycle -Increased atmospheric carbon levels -Wetlands can be carbon source or sink Ecosystem Services -C sequestration -Nutrient storage -Biodiversity -Flood control

Wetlands are important global carbon sinks

Millennium Ecosystem Assessment Report, 2005

CO2

Organic C POC, DOC

CO2

CH4

CH4

Aerobic

Litter/Soil

Anaerobic

Litter/Soil

Water

DOC

CO2

Litter fall,

Exudation

Methanogenesis

Photosynthesis

Simplified Carbon Cycle

Controls on wetland carbon cycle: Water level

Environmental factors influence productivity and microbial function

Controls on wetland carbon cycle:

Temperature

Environmental factors influence productivity and microbial function

Zhou et al 2009

Controls on wetland carbon cycle:

Temperature

Environmental factors influence productivity and microbial function

Zhou et al 2009

Controls of wetland carbon cycle: Plant Chemistry

Non-Humic Compounds

-Simple sugars, proteins, peptides, amino acids, fats, etc.

-Labile (rapid turnover)

-Small fraction of C

Humic Compounds

-Composed of lignin, cellulose

-High C:N

-Highly aromatic

-Phenols can slow/inhibit microbial activity

a) phenolic acids (gallic acid), secondary metabolite

b) lignin requires specialized enzymes and has complex 3D structure

CO2

CH4

CH4

Aerobic

Litter/Soil

Anaerobic

Litter/Soil

Water

DOC

CO2

Methanogenesis

Photosynthesis

Question 1: Is litter decomposition controlled by plant chemical composition or the marsh environment?

Organic C POC, DOC

CO2 Litter fall,

Exudation

Approach: Reciprocal transplant experiment

X X

X X

Site

Litte

r

P

P

T

T

December to November (344 d) = Annual

0

10

20

30

40

50

60

BPP BPT BTP BTT

Mass L

oss (

%)

Cold Season Warm Season Total

Site drives decomposition through annual cycle

Phragmites Dominant

P T T

Typha Dominant

Litter Species Site

P

A A

B B

0

5

10

15

20

25

30

35

40

45

50

Cold Warm Season

Phragmites Typha

APR

6

APR

26

Month

Day

MAY

17

JUN

8

JUN

28

JUL

19

AUG

22

NOV

9

˟

+

Tem

per

atu

re (°C

) Temperature similar in Phragmites and Typha sites

0

5

10

15

20

25

30

35

40

45 W

ate

r D

ep

th (

cm

)

BP

BT

Cold Warm Season

Phragmites Typha

APR

6

APR

26

Month

Day

MAY

17

JUN

8

JUN

28

JUL

19

AUG

22

OCT

5

NOV

9

Water level lower in Phragmites site

Question 2

How does soil microbial activity change in response to marsh water levels?

CO2

Organic C

CH4

Aerobic

Litter/Soil

Anaerobic

Litter/Soil

Water

CO2

Litter fall,

Exudation

Photosynthesis

How does microbial activity change in response to marsh water level?

POC, DOC

CO2

CH4 DOC Methanogenesis

• Soil incubations & Gas chromatography

• Estimate of microbial response to environment

• Measure of wetland function (C release)

Gaseous carbon production (CO2, CH4)

Approach: Water Level Manipulations

X X

X X

Soil

Wate

r Level

S = Submerged, Anoxic F = Field Moist, Oxic

S

P T

F

0

200

400

600

800

1000

1200

1400

BPAerobic BPAnaerobic BTAerobic BTAnaerobic

FM

B

FM

µgC

O2 g

So

il-1

d-1

Water

Level

Soil Phragmites

SU

Typha

A

A

B

SU

CO2 production higher when water level is low

0

200

400

600

800

1000

1200

1400

BPAerobic BPAnaerobic BTAerobic BTAnaerobic

FM FM

µgC

O2 g

So

il-1

d-1

Water

Level

Soil Phragmites

SU

Typha

A

A

SU

CO2 production similar in Phragmites and Typha soils

Question 3

Do the differences in plant leachate chemistry increase or inhibit microbial activity?

Approach: Plant Leachate Additions

X X

X X

X X L: dH2O (control) C: Phragmites (83.07 ppm) R: Typha (183.0 ppm)

Site

Leachate

P T

T

P

W

0

50

100

150

200

250

psw psp pst tsw tst tsp

µgC

O2 g

Soil

-1 d

-1

P P

B

A,B

Phragmites

W T T

Typha

Leachate Soil

W

A C,D

D

C,D

W = dH2O P = Phragmites T = Typha

Typha leachates increase CO2 in Phragmites site

0

50

100

150

200

250

psw psp pst tsw tst tsp

µgC

O2 g

Soil

-1 d

-1

P P

B

A,B

Phragmites

W T T

Typha

Leachate Soil

W

A,C C,D

D

C,D

W = dH2O P = Phragmites T = Typha

Phragmites leachates decrease CO2 in Typha site

0

50

100

150

200

250

psw psp pst tsw tst tsp

µgC

O2 g

Soil

-1 d

-1

P P

B

A,B

Phragmites

W T T

Typha

Leachate Soil

W

A,C C,D

D

C,D

W = dH2O P = Phragmites T = Typha

CO2 production higher in Phragmites site

2010 Phragmites Typha

1647 652

Primary Production

Ratio = 2.5P :1T

0

500

1000

1500

2000

2500

1 2

0

1000

2000

3000

4000

5000

6000

1 2

Dry

we

igh

t (g

m-2

y-1

) Typha Phragmites

2010 2011

Pla

nt

bio

mas

s C

(g

m-2

y-1

)

2010 2011

Typha Phragmites

Carbon Dynamics Phragmites (Invaded) Typha

Fixed C Variable Variable

Soil C + -

SUVA + -

Soil CO2 + -

Soil CH4

- +

Litter Loss (ABG CO2)

+ -

Inputs

Net C Storage

Outputs Burning?

Dewatering

Example of a Phragmites reed bed system. Some excavated reed bed dewatered sludge material is located in the foreground (image courtesy Miles Falck, Great Lakes Indian Fish and Wildlife Commission). http://greatlakesphragmites.net

Future Research

"A lot of the traditional work on these cyanobacterial blooms focuses on phosphorus as being the main culprit," Dick said. "But in western Lake Erie we're seeing an intriguing correlation between nitrogen availability and bloom toxicity that we'll be following up on.“ http://ns.umich.edu/new/releases/23030-multiple-factors-including-nitrogen-availability-may-shape-toxicity-of-lake-erie-cyanobacterial-blooms

http://www.slideshare.net/nirmalajosephine1/biology-form-4-chapter-8-dynamic-ecosystem-part-5

Acknowledgements

Dr. Kristi Judd

Dr. Steve Francoeur

Dr. Gary Hannan

Audrey Johnson

Jay Krystyniak

Jerry Tyrrell

Penny Richardson-Bristol