Hongjun Wang

1 Duke University Wetland Center, Nicholas School of the Environment, Box 90333, Duke University, Durham, NC 27708, USA

E-mail: hw93@duke.edu

T

Moss Shrub/Tree

Rus

sia

Can

ada

Wes

tern

Eur

ope

Mid U

SA

SE U

SA

Louisian

a

Florid

a

Kalim

anta

n

0

100

200

300

400

C a

ccum

ula

tion (

g m

-2 y

r-1)

Bakker et al., 1997

• Fate of boreal peatlands?

• Why do non-boreal peatlands exist?

• Carbon sink or source under climate change?

Scientific Questions

Myers-Smith et al., 2011

Climate change-induced plant succession

Drought + Warming

Moss Shrub Tree

? Carbon stock

What controls C decomposition?

Generally, low C quality decreases C decomposition

Not only anoxia, other factors, substrate or buildup chemical resistance must exist to reduce decomposition under drought

Natural site Restored site Drained site Pocosin Bog Study sites in coastal NC

Long-term treatments in field

Natural Drained Restored

Biomass: 71.9 Mg C ha-1 20.1 Mg C ha-1 4.8 Mg C ha-1

Field and Lab Experiments

Gas chamber

Phenolic inhibitory effect is defined as a negative value of Pearson’s r between soil respiration and soluble phenolics in the surface soil.

Lower water level, higher phenolic inhibitory effect

-90 -80 -70 -60 -50 -40 -30 -20 -10

0.3

0.4

0.5

0.6

0.7

r = 0.8965

p = 0.015

Ph

eno

lic in

hib

itory

eff

ect

Water level (cm, below ground surface)

Phenolics inhibit SR

2.3 2.4 2.5 2.6 2.7 2.8 2.9

0.5

1.0

1.5

2.0

2.5

3.0

C

O2 e

mis

sio

n (m

ol m

-2 s

-1)

Log (Soluble phenolics(g g-1 dry soil))

r = 0.833

p < 0.0001

Highest available and total phenolics found in shrub leaves

Sphagnum Herbs Shrubs Trees0

10

20

30

40

50

60

70

80 Pocosin

Boreal peatlands

To

tal

ph

eno

lics

(m

g C

g-1

dw

)

Plant community

0

10

20

30

40

50

60

70 Ratio (available/total)

Ratio (

%)High

resistance

Summary 1

Short-term

drought

Short-term

drought

Long-term

moderate

drought

Long-term

moderate

drought

Phenol

oxidase

Plant

community Phenolics Phenolics

Peat

decomposition

Peat

decomposition

_

+

+

+

_

Wang, H., C. J. Richardson and M. Ho, 2015. Dual controls on carbon loss during drought inpeatlands. Nature Climate Change, 5: 584–587.

Phase 2

Wang et al., under review

Shrubs Sphagnum

0

10

20

30

40

50

60

70

80

90

100

Re

lative

ab

ou

nd

an

ce

of fu

ng

i (%

)

Dominant plant community

Unknow Fast-growing Slow-growing

Slow-growing microbes with low carbon

turnover rate in shrub peatlands

0

200

400

600

800

2200

2400

2600

dd

c

Sp.Sp.

Sp.Sh.

Sh.Sh.

CO

2 e

mis

sio

n (

mg h

r-1 g

-1 M

BC

)

Treatment (soilinoculum

)

d

a

b

Sh.Sp.

Min.Sh.Min.

Sp.0 200 400 600 800 1000 1200 1400 1600

0

20

40

60

80

100

Slow-growing fungi Fast-growing fungi

Re

lative A

bun

da

nce

(%

)

Phenolics (g C /g dry soil)

Wang et al., under review

Peatlands can adapt to climate change by gradually shifting microbial & plant communities to maintain essential carbon sequestration functions and processes.

Phenolics linked plant-microbe symbioses

Summary 2

Can we enhance phenolic or phytochemical linkage in farmlands?

Right crops, right fertilizer, right

inoculants, right-plant-induced chemicals ?

Application in Soil Health

Phytochemicals

Diversity

Nutrients

Water

Biome health

Soil carbon

Pathogen

Pest

Soil erosion

Beneficial microbe

Phytochemical Linkage to Health of Soil, Plant, Animal and Human

• How human activities and climate change have changed the linkage in natural ecosystem and farmlands wetlands?

• How can we fix and enhance this linkage to improve ecosystem sustainability and resilience?

An example―Organic Farming

Barański et al. 2014. Higher antioxidant and lower cadmium concentrations and lower incidence of pesticide residues in organically grown crops: a systematic literature review and meta-analyses. British J. Nutrition. 112:794-811.

• Phenolic acids 19%

• Flavenones 69%

• Stilbenes 28%

• Flavones 26%

• Flavonols 50%

• Anthocyanins 51%

• Cadmium -48%

Questions？

Acknowledgements: Prof. Curtis J. Richardson, Dr. Mengchi Ho, Dr. Neal Flanagan and other members at Duke University Wetland Center

US DOE Office of Science, Terrestrial Ecosystem Sciences, Coastal Carolina/ Southeastern Virginia Strategic Habitat Conservation Team, U.S. Fish and Wildlife Service-Region 4, The Nature Conservancy of North Carolina and the Duke University Wetland Center Endowment provided financial support