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
on d
ensit
y (k
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