Hojeong KangYonsei University

Korea2009 TERRECO

Effects of Water Level Drawdown& Elevated Temperature

on Peatland Microbes

Contents

BackgroundsBackgrounds11

Water Level DrawdownWater Level Drawdown22

Temperature riseTemperature rise33

SummarySummary44

Backgrounds- Climate Changes & Peatlands

Climate changes include

Higher temperature

Elevated CO2

Drought & flooding

Sea level rising

Rising temperature (Global)

IPCC (2007)

IPCC (2007)

Changes in precipitation 1999 vs. 1900

IPCC (2000)

Projections of future precipitation

2090-2099

December to February June to August

IPCC (2007)

• Accumulation of un-decomposed organic matter as peat

• C sink– 455 Pg C (cf. 750 Pg C in the atmosphere)– 1/3 of SOM

• Destruction → CO2, DOC releases– Excavation for energy source– Land use changes– Climate changes

Peatlands

Classification for peatlands

Bog Fen Riparian

Nutrient Oligotrophic Mesotrophic Eutrophic

HydrologyOmbrogenous

(precipitation)

Transition

(groundwater flow)

Minerogenous

(stream or lakes)

Soil pH 3.8 ~ 4.4 4.0 ~ 6.3 6.0 ~ 6.5

Organic matter 85 ~ 99% 20 ~ 90% 5 ~ 30%

VegetationMoss

(Sphagnum)

Grass and Sedge (Carex, Juncus,

Festuca)

Reed or tree(Phragmites,

Cypress, Salix)

• Play a key role in peatland biogeochemistry– CO2, CH4, N2O production

– Decomposition of OM

• Culture-based methods account for only 1-5%

• Molecular approaches– T-RFLP, DGGE– Realtime Q-PCR– Sequencing (Cloning, pyrosequencing)

Microbes

• To determine effects of – water level drawdown during summer– warming for 3 years

• on microoganisms in peatland– Microbial community structure– Microbial abundance

Objectives

Water Level Drawdown

Objectives• Effects of drought on microbial

communities in wetlands

• Soil cores collected from three types of wetlands (riparian, fen, and bog) in north Wales, UK.

Organic content (%)20 40 60 80

3

4

5

6

7

Nitro

ge

n (%

)

1

2

3

4

pHNitrogen

Lake (Riparian)Fen

Bog

So

il p

H

Source: Mitch and Gosselink, 2000

Microcosms

Riparian Fen Bog

Surface

10cm

20cm

11cm

4 weeks incubation

Draining

39% ±1.4 55% ±1.7 55% ±1.2

Methods

• Analysis of Microbial communities– Eubacteria (bacterial 16S rRNA genes)– Denitirifiers (nirS genes)– Methanogens (mcrA genes)

• Real-Time PCR (Abundance)• T-RFLP (Diversity, composition)

(rdp8.cme.msu.edu/html/t-rflp_jul02.html)

T-RFLP (Terminal Restriction Fragment Length Polymorphism)

Real Time Q-PCR

(Source: Quantabio.com)

Drought effect: Abundance (RT-PCR)

Microbial community

TreatmentsGene copy numbers g-1 dry soil (Mean ± SEM)

Riparian Fen Bog

BacteriaControl

5.6×108 ± 1.9×108

7.7×109 ± 2.1×109

1.7×1010 ± 3.2×109

Drought2.0×108 ± 5.3×107

1.1×109 ± 2.0×108*

2.3×109 ± 2.0×108**

MethanogensControl

1.8×107 ± 6.3×106

3.3×108 ± 2.7×108

1.4×108

±2.0×107

Drought7.2×106 ± 2.2×106

5.8×108 ± 5.6×108

1.7×107± 3.4×106***

DenitrifiersControl

1.4×107 ± 2.7×106

1.9×108 ± 1.5×107

1.4×108 ± 3.0×107

Drought9.7×106 ± 1.5×106

4.5×107± 6.9×106***

2.1×107 ± 2.7×106**

Soil Biology & Biochemistry (2008)

Drought effects: Composition

MRPP testA statistic

Difference in proportional abundance

Bacteria Methanogens Denitrifiers

Bog - - -

Fen - - -

Riparian 0.04 (p < 0.05) - -

Drought effects: Diversity

Microbial community

TreatmentsMean ± SEM

Riparian Fen Bog

BacteriaControl 3.9 ± 0.09 3.6 ± 0.11 3.2 ± 0.07

Drought 3.3 ± 0.11* 3.7 ± 0.05 3.5 ± 0.13(*)

MethanogensControl 0.8 ± 0.49 1.0 ± 0.13 1.3 ± 0.12

Drought 0.9 ± 0.27 1.0 ± 0.38 1.3 ± 0.38

DenitrifiersControl 1.9 ± 0.39 1.8 ± 0.38 1.8 ± 0.22

Drought 2.3 ± 0.18(*) 2.1 ± 0.37 2.2 ± 0.29

Bacteria Methanogens Denitrifiers

Abundance Bog

Fen -

Riparian - - -

Composition Bog - - -

Fen - - -

Riparian - -

Diversity Bog - -

Fen - - -

Riparian -

Drought effects: Summary

↓

↓

↓↓

↓

↓

↑(*)

↑(*)

Change

Drought

Decreased abundance in bog and fen

No changes in composition

Various responses in diversity

Summary

Elevated Temperature

Control: Ambient temperatureTreatment: + 3° C for 3 yearsfor 3 years

SolardomesSolardomes

Warming on peatland (RT-PCR)

a

b

a'

b'

Methanogens Eubateria

1~3

9~11

17~19

Gene copy numbers g-1 dry soil

1e+6 1e+7 1e+8 1e+9 1e+10

Dep

th (

cm)

The Ratio of Methanogens to Eubacteria (%)

0 3 6 9

ControlWarming

* p = 0.02

(*) p = 0.07

(*) p = 0.07(*) p = 0.09

** p < 0.01** p < 0.01

Kim et al. (unpublished data)

Warming effects: MRPP test

TreatmentsA statistics

Warming effect

Soil Depth Eubacteria MethanogenSurface 0.220 (P<0.01) -Middle 0.190 (P<0.01) -Deep - -

EubacteriaEubacteria

Methanogen

Methanogen

Summary

Decrease in abundance in bog and fen

No changes in composition

Various responses in diversity

Water level drawdown

Elevated temperatureDecrease in methanogen / eubacterial abundanceChanges in eubacterial communityDecreases in diversity of eubacteria

• Prof. C. Freeman, Drs. N. Fenner, S-Y. Kim, S-H. Lee• NRF & EcoSTAR for financial supports

Acknowledgements