Understanding Anthropogenic Impact on Peatlands GHGs Dominique - - PowerPoint PPT Presentation

Understanding Anthropogenic Impact on Peatlands GHGs

Dominique Blain, PhD Dominique Blain, PhD IPCC TFI Side Event M iti H t l B Maritim Hotel, Bonn 8 June 2011

Drawing from Quinty and Rochefort, 2003

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A P d A h A Proposed Approach

 Measuring GHG fluxes  Understanding drivers of GHG dynamics  Understanding drivers of GHG dynamics  Understanding GHG dynamics in degraded,

rewetted and restored peatlands rewetted and restored peatlands

 Putting it all together

Peatlands are the main wetlands reservoir for soil C. World-wide they contain about 450 Gt C, most in the northern peatlands & about 60 Gt in tropical regions (this number very uncertain).

After Strack et al. 2008. Peatlands and Climate Change. International Peat Society, Vapaudenkatu, Jyvaskyla, Finland.

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Measuring GHG fluxes in northern peatlands (g C m-2 yr-2)

R E t R i ti

NEE = GPP - Re

78 ±59 413 ±92

GPP – Gross primary productivity (CO2) Plant respiration (CO2) Soil respiration (CO2) Re - Ecosystem Respiration

491 ±130 8 ±7

(

2)

vascular plants

(

2)

Methane flux (CH4)

491 ±130

moss water table

methane

• xidation

Peat/soil water table

methanogenesis

NEP = - NEE

20 ±12

Blain & Lafleur, 2010

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Compilation of annual measured C budgets for peatland sites peatland sites

 C = CO2-C + CH4-C + DOC + Cppt

in 250 300

Worrel et al. (2003) Roulet et al.( 2007)

C ga 150 200 m-2 yr-1)

Nilsson et al. (2008) Dinsmore et al. (2010) Flanagan et al. (2010) L d (2009)

50 100 flux (g C

Lund (2009) Jac.-Kor. (2009)

C loss 100

• 50

C

• 100

NEP CH4 DOC Precip Total C

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• LAI and pH affect both GPP and NEE

GPP i bl th R

Understanding drivers of Net Ecosystem Exchange

• GPP more variable than Re
• Overall: peatland type not a good predictor of NEE

After Lafleur, 2009

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• CH4 emissions highly variable

Understanding Controls over CH4 emissions

CH4 emissions highly variable

• Winter emissions contributing about 10% of the annual emissions
• Spatial ‘hotspots’

Lafleur, 2009

1000

Fort Simpson NWT Schefferville QC Thompson MB Clay Belt ON Finland

• S. Hudson Bay Lowland

Churchill, MN Schefferville QC Dorset ON Kejimkujik NS Riviere du Loup QC Shippagan NB

B

WTD a key factor in CH4 emissions

10 100 ux (mg m-2 d-1)

Riviere du Loup QC Shippagan NB Mer Bleue ON Radisson QC

4

(depth of oxic and anoxic parts of the peat) Different intercepts : mean or base rate

1 10 Average CH4 fl

Mer Bleue

p

• f CH4 emission controlled by other

factors (vegetation, mean climate, etc.)

after Moore TR, unpub.

0.1

• 60
• 50
• 40
• 30
• 20
• 10

, p

Average water table position (cm)

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Carbon is also lost in dissolved form:

DOC losses from peatlands range from <5 to 40 g C m-2 yr-1 DOC as a percent of NEP range averages from 5% to 70%; DOC as a percent of NEP range averages from 5% to 70%; in individual years it can be >100% DOC export is controlled by 1) production in the peat profile and 2) discharge (Q):

• variations in flux at a given peatland are largely

determined by Q

• differences among peatlands in similar hydrologic

settings are production related

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Peatlands Drainage: what happens

GPP G i Re - Ecosystem Respiration

NEE = GPP - Re

GPP – Gross primary productivity (CO2) Plant respiration (CO2) Soil respiration (CO2) Methane flux

vascular plants

Methane flux (CH4)

moss water table

methane

• xidation

Acrotelm

Peat/soil

methanogenesis

Catotelm

NEP = - NEE

Strack and Waddington, 2007

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I t i f t

Intensity of post-drainage utilization varies

Intensive forestry Pasture Cropping Peat extraction

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Degraded peatlands: losses of functions

Non-functional acrotelm: Loss of peat hydraulic properties

Price and Whitehead, 2004

Erratic water table regime : drying and rewetting episodes Persistent source of CO2 fluxes t t h (100% 400% f

McNeil and Waddington, 2003

to atmosphere (100% - 400% of pristine)

Waddington et al., 2002 Waddington et al 2008

Little re-colonization by Sphagnum mosses

Waddington et al., 2008 Quinty and Rochefort, 2003

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A peatland may not restore on its own

‘Natural’ recolonization of degraded peatlands is slow, and vegetation establishment dominated by vascular vegetation (herbs and shrubs) with poor moss colonization Rewetting reduces Re but does not stabilize WT fluctuations if f ti l l i i i (herbs and shrubs), with poor moss colonization

Poulin et al., 2005 Waddington et al., 2008

Restoring C sink function involves water table regulation by functional moss layer is missing

Waddington and Day, 2007

Post-mining restoration techniques have been developed and fi ld t t d f ti l t l d C t ti f ti Restoring C sink function involves water table regulation by living moss layer (acrotelm) field tested: functional acrotelm and C sequestration function re-established within ~ one decade.

Lucchese et al., 2010

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Contrasting GHG dynamics of Peatlands in different states different states

Pristine peatlands : long-term C sequestration and climate cooling effect; Re suppression in anoxic zone; hydraulic properties

• f moss layer key factor in WTD regulation; climate and vegetation

controls on NEE and CH4 Degraded peatlands : drained, with moss layer affected to various degrees by subsidence, compaction, removal. High Re sustained

• ver decades.

Re-wetted peatlands : reduction in Re, WT subject to high fluctuations if not regulated (climate sensitive), harsh environment for moss re colonization for moss re-colonization Restored peatlands : C sequestration function re-established through a functional acrotelm.

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Contrasting GHG dynamics of Peatlands in different States

Pristine Degraded Re-wetted Restored

States

Pristine Degraded Re wetted Restored Vegetation & peat Intact moss cover and peat structure No moss; peat compaction & subsidence Little or no moss Re-established moss layer

ctions

Hydrology structure WTD fluctuation subsidence WTD highly fluctuating – WTD highly fluctuating – if WTD and acrotelm

Func

regulated by moss climate sensitive not regulated fluctuations regulated C exchange GEP > Re & Re dominates; Re smaller; GEP>Re; CH4 NEP Long-term C C source to C source to net C sink g more variable GEP 0

e

; CH4 loss larger GEP Re; CH4 possibly larger g sink atmosphere atmosphere net C sink

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Vegetation influences restoration pathway: what are the restoration objectives? what are the restoration objectives?

Rehabilitation To re-establish the productivity and some, but not necessarily all,

• f the plant and animal species thought to be originally present

at a site. Ex: re-establish C sink through perennial, vascular vegetation Restoration R t bli hi th d t t d ti it d i Re-establishing the presumed structure, productivity and species diversity that was originally present at a site that has been degraded, damaged or destroyed. In time, the ecological processes and functions of the restored habitat will closely match and functions of the restored habitat will closely match those of the original habitat. Ex: re-establish C sink and hydrological regulation by moss layer

Nelleman and Corcoran 2010; FAO 2005.

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Improved estimation of anthropogenic emissions and removals in peatlands involves: emissions and removals in peatlands involves: Including key elements of C budget: NEE, CH4, DOC Understanding the state of peatlands and h f ti ff t d how functions are affected Determine restoration pathway Determine restoration pathway

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References

Bl i D d L fl P 2010 S i d d ti ti f tl d i i IPCC E t ti WMO G 20 O t b 2010 Blain D. and Lafleur P. 2010 Science advances and estimation of wetland emissionsIPCC Expert meeting WMO Geneva, 20 October 2010

• FAO. 2005 Helping Forests Take Cover. RAP Publication. 2005/13. /www.fao.org/docrep/008/ae945e/ae945e05.htm.

Jackowicz-Korczynski, M. 2009. Land-atmosphere interactions at a subarctic palsa mire. Unpublished Ph.D. thesis, Lund University, Lund Sweden, 102 p. Lafleur, P.M. 2009. Connecting Atmosphere and Wetland: Trace Gas exchange. Geography Compass, 3/2, 560–585. Lucchese, M.C., Waddington, J.M., Poulin, M., Pouliot, R., Rochefort, L., and Strack, M. 2010. Organic matter accumulation in a restored peatland: g g p Evaluating restoration success. Ecological Engineering, 36, 482–488. Lund, M. 2009. Peatlands at a Threshold. Unpublished Ph.D. thesis, Lund University, Lund Sweden, 163 p. Lund, M., Lafleur, P.M., Roulet, N.T., Lindroth, A., Christensen, T.R., Aurela, M., Chojnicki, B.H., Flanagan, L.B., Humphreys, E.R., Laurila, T., Oechel, W.C., Olejnik, J., Rinne, J., Schubert, P. and Nilsson, M.B. 2010. Variability in exchange of CO2 across 12 northern peatland and tundra sites. Global Change Biology, 16, 2436–2448. McNeil, P. and Waddington, J.M. 2003. Moisture controls on Sphagnum growth and CO2 exchange on a cutover bog. Journal of Applied Ecology, 40 (2), 354–367. Nellemann, C., Corcoran, E. (eds). 2010. Dead Planet, Living Planet – Biodiversity and Ecosystem Restoration for Sustainable Development. A Rapid Response Assessment. United Nations Environment Programme, GRID-Arendal. Birkeland Trykkeri AS, Norway. P li M R h f L Q i F L i C 200 S i f i d l d i E C d C di J l f B 83 39 Poulin, M., Rochefort, L., Quinty, F., Lavoie, C 2005. Spontaneous revegetation of mined peatlands in Eastern Canada. Canadian Journal of Botany 83, 539- 557. Price, J.S. and Whitehead, G.S. 2004. The influence of past and present hydrological conditions on Sphagnum recolonization and succession in a block-cut bog, Québec. Hydrological Processes, 18 (2), 315–328. Quinty, F. and Rochefort L. 2003. Peatland Restoration Guide, second edition. Canadian Sphagnum Peat Moss Association and New Brunswick Department f N t l R d E Q éb Q éb

• f Natural Resources and Energy. Québec, Québec.

Strack, M. (ed.) 2008. Peatlands and Climate Change . International Peat Society, Saarijärven Of fset Oy, Saarijärvi, Finland. Waddington, J.M., Warner, K.D., and Kennedy, G.W. 2002. Cutover peatlands: A persistent source of atmospheric CO2, Global Biogeochemical Cycles, 16(1), 1002. Waddington J M and Day S M 2007 Methane emissions from a peatland following restoration Journal of Geophysical Research G: Waddington, J.M. and Day, S.M. 2007. Methane emissions from a peatland following restoration. Journal of Geophysical Research G: Biogeosciences, 112 (3), art. no. G03018. Waddington, J.M., Tóth, K., Bourbonniere, R. 2008. Dissolved organic carbon export from a cutover and restored peatland. Hydrological Processes, 22 (13) 2215–2224.

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