Quantifying terrestrial ecosystem carbon stocks for future GHG mitigation, sustainable land-use planning

and adaptation to climate change,Québec, Canada

Michelle Garneau, Professor Simon van Bellen, Associate professor

Geotop Research CenterUniversité du Québec à Montréal, Montréal, Canada

Global Symposium on Soil Organic Carbon FAO, Rome – 22 March 2017

Distribution of peatlands in the Canadian boreal beltafter Tarnocai, 2011

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50,000

100,000

150,000

200,000

250,000

300,000

350,000

400,000 Area (km²)Frozen Fens

Frozen Bogs

Unfrozen Fens

Unfrozen Bogs

• 2nd largest country (9.9 million km2) • Peatlands: 13-17% of terrestrial surface • ≥ 150 Gt of carbon (Tarnocai, 2011)• 64% in the boreal and 33% in the

subarctic regions

Northern ecosystem carbon cycle

Global boreal forests store ~272 Gt C (Pan et al., 2011)

• Carbon accumulation is mostly cyclic

• Large emissions of CO2 and CH4 linked with natural disturbance (fires) and human intervention

Northern peatlands represent 500-600 Gt C or ~30% of the terrestrial carbon stock (Yu, 2012; Turetsky et al., 2015)

• Accumulation mostly since the last glaciation

• Sinks of carbon, but sources of methane (CH4)

Peatlands have had a net cooling effect on the global climat during the Holocene, removing CO2 from the atmosphere: -0.22 to -0.56 W m-2 (Frolking & Roulet, 2007)2007)

O2CO2

C

CC

C

Photosynthesis

CO2

C

Forest stand

CH4CC

C

C CC

Forest stand life cycle = decades to a few centuries

C C

CH4

CCCC

CCC

Peatland

CH4CH4CO2

PhotosynthesisCO2

C

CCC

C

C

O2

C

Peatland life cycle = millennia

CO2

CC

Carbon stock inventory

• Agriculture Canada: Tarnocai, 2011• Natural Resources Canada (CFS): CaMP for

CBM-CFS• Ministère Développement durable,

Environnement et de la Lutte contre les changements climatiques (MDDELCC)

• Québec:• First extensive carbon stock inventory• Plan Nord: harmonizing the economic,

social and environmental aspects on the northern territory

• 2035: 50 % territory for conservation purposes: conservation target• Biodiversity• Carbon stocks for climate change

mitigation (Climate Change Action Plan 2013-2020)GoogleEarth

Neoglacial

Temporal trends in carbon accumulation

Garneau et al., 2014

Overall slowdown of carbon accumulation linked with Neoglacial cooling, based on the analysis of six ecoregions and various peatland types

Insolation June (W m-2)

Carbon accumulation rate

Spatial trends in carbon accumulation• Spatial database from the

MDDELCC Ecological Inventory: 92 natural regions, average area - 17 660 km2

• Peatland carbon density (kg C m-2) for 30 sites

0 200100 Kilometers

N

Carbon density modelling including environmental variables

Cumulative shortwave radiation

Growing-season precipitation

Latitude

Climatic/spatial variables:• Mean annual temperature• Annual precipitation• Growing-season precipitation• Growing-degree days above 0ºC• Growing-season cumulative shortwave radiation• Growing-season average shortwave radiation• Latitude

Predictive model: r2 of 0.55 and RMSE of 38.6 kg C m-2

Correcting bias created by the use of central cores

Mean = 0.65

Forest soil carbon density (kg C m-2) and environmental variables

Carbon density quantified separately for organic and mineral horizons

• managed forests: 284 soil pedons • unmanaged forests: 52

observations of carbon density

Organic horizons more vulnerable to release, through fire and climate change

Peatlands Forest soils

Boreal carbon density patterns in Quebec

Carbon stock: 7.9 Gt C (5.6-10.6)

Total area: 92 500 km2

(MDDELCC, 2016)

Mean carbon density: 85.5 kg C m-2

Carbon stock: 6.2 Gt C

Total area: 416 800 km2 of

managed forests and 139 700 km2 of unmanaged forests (MDDELCC, 2016)

Mean carbon density: 10.9 kg C m-2, 11.7 kg m-2 in managed forests and 9.4 kg m-2 in

unmanaged forests

Peatland carbon stocks exceed forest soil stocks, despite their lower areal coverage

Pea t la n d s Ma n a g ed fo res t s

Un ma n a g ed fo res t s

85.5

5.0 3.96.7 5.6

Carb

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g m

-2)

Peat lan d s Man ag ed fo res ts

Un man ag ed fo res t s

7.91 2.10

0.542.79

0.78

Mineral horizon Organic horizon

Carb

on st

ock

(Gt)

+6ºC

+3ºC

+1.5 - 2ºC

Hiver

+0.3 mm jr-1

-0.3 mm jr-1

Longer growing seasons and positive moisture balance: increased potential for carbon sequestration

Warming and negative moisture balance: decreased potential for carbon sequestration

Soil moisture balance (P-ET) Temperature

+2.5ºC

Projected changes in summer climate and peatland carbon dynamics (2041-2070)

Ouranos, 2016

+3ºC

+1,5 - 2ºC +0,3 mm jr-1

-0,3 mm jr-1

Soil moisture balance (P-ET) Temperature

+2,5ºC

Climate change and permafrost peatlands

Permafrost degradation:

• Palsa collapse• Increased emission of CH4

• Gradual drying, return of xerophilous Sphagnum moss

• Return of net accumulation

~50-70 years until return of net carbon accumulation (Turetsky et al., 2007, Sanderson, 2016, Lamarre et al., 2012)

Ouranos, 2016

+6ºC

Hiver

Warming and negative moisture balance: increased fire severity, especially in western Quebec

Projected changes in summer climate and forest soil carbon (2041-2070)

+3ºC

+1,5 - 2ºC +0,3 mm jr-1

-0,3 mm jr-1

Soil moisture balance (P-ET) Temperature

+2,5ºC

Ouranos, 2016

The total carbon stock is the

equivalent of a total sink of 51.7 Gt

CO2 –eq.

In 2014, anthropogenic emissions in

Quebec were 82.1 Mt CO2-eq., or

1.6‰ of the total carbon stock

Peatland carbon density (kg C m-2) is 7 to 8 times higher than those of the forest soil: 85.5 kg C m-2 vs. 10.9 kg C m-2

The total boreal forest soil and peatland carbon stock is estimated at 14.1 Gt C

(MDDELCC, 2016)

Carbon stocks vs. anthropogenic emissions

• The Quebec boreal forest soil and peatland carbon stock is estimated at 14.1 Gt C• At 7.9 Gt C, peatlands represent more than half of this stock

• Boreal forest soils store around 6.2 Gt C, with 79% in managed forest soils (vs. 21% in unmanaged forest soils) and 57% in mineral horizons (vs. 43% in organic horizons)

• Future GHG mitigation policies and sustainable land-use planning should be supported by an increase in investments in peatland, wetland and forest conservation, management and rehabilitation to limit greenhouse gas emissions

Thank you for your attention