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Greenhouse gas dynamics of northern peatlands related to
climate variability and land use
Pertti J. Martikainen
University of Eastern Finland, Department of Environmental Science
Biogeochemistry Research Group
Nordic Seminar on Peatland Drainage, 5 November 2013, Kuopio
Temperature Precipitation
Hydrology
(water table)
Biogeochemistry of peatlands
(Greenhouse gas fluxes)
Managements
Temperature Precipitation
Hydrology
(water table)
Biogeochemistry of peatlands
(Greenhouse gas fluxes)
Managements
Permafrost
melting
- Subsidence
Arctic peatlands
Biological processes and greenhouse gases in wetlands
CO2 N2O CH4 N2O CO2 CH4
High water table (natural
wetland) Lowering in water table
(drying, draining of wetlands)
Water table
Water table Anaerobic
decompo-
sition
Anaero-
bic de-
compo-
sition
CH4 oxi-
dation Aerobic
decompo-
sition
Denitrification
Nitrogen
minera-
lization,
nitrifi-
cation and
denitri-
fication
CH4 oxi-
dation
Aero
bic
decom
po-
sitio
n
Vegetation
Aerobic soil
Anaerobic soil
Photosyn-
thesis
Aurela et al. (2004)
A fen in Kaamanen, Finland
NEE = PG – (RTOT + W)
NEE = net ecosystem exchange
PG = Gross photosynthesis
RTOT = Total respiration
W = weathering (e.g. leaching)
Carbon dioxide dynamics of peatlands – carbon accumulation as organic
matter (peat)
Recent carbon accumula- Carbon accumulation
tion (CO2 exchange studies) during thousands of years
Present total pool of carbon in boreal and
subarctic mires is 270-370 Pg
(Turunen et al. 2002)
- 20 -30 % of the global carbon pool in soils
- 40 % of the CO2-C in the atmosphere
In Finland: In peat 5.3 Pg C (Turunen, 2004)
- is 8 x that in tree stand
5 x that in upland forest soils
Long-term average carbon accumulation
during the peatland development for
the Finnish natural peatlands is
18.5 g C m-2 yr-1 (Turunen et al. 2002)
(raised bog: 26 g C m-2 yr-1, aapa mires
17 g C m-2 yr-1)
Turunen et al. (2002)
Climate change induced changes in CO2 and CH4
fluxes of Finnish pristine peatlands up to 2099
Jinnan Gong et al. (2012): Ecological Modeling 244: 63-78
Jinnan Gong et al. (2013): Ecological Modeling 263: 64-80
Predicted development of temperature and precipitation in Finland 2000-2099
(reference period 1971-2000) C
ha
ng
e in
te
mp
era
ture
(0C
)
Mean annual temperature Mean annual precipitation
Ch
an
ge
in
pre
cip
ita
tio
n (
%)
Year Year
ACCLIM 2009
Temperature increase
- Annual mean: 2-6 0C
- Winter: 3-9 0C (more in the north)
- Summer: 1-5 0C
Precipitation increase (more in the north)
- Winter: 10-40 %
- Summer: 0-20 %
2000 - 2020 - 2060-
2019 2059 2099
Drained
peatlands
Pristine
fens
Pristine
bogs
Ecological Modelling 244: 63-78 (2012)
Predicted changes in water table of Finnish peatlands 2000-2099:
Regional modeling
Mean monthly WT decreases from
April to September (the lowering
increases up to 2099, most significantly
in May
Maximum drawdown of WT:
- Pristine fens 5.2 cm (2060-2099),
(western Finland)
- Pristine bogs 3.3 cm (2060-2099)
(west)
- Drained peatlands 0.1-0.7 cm
Jinnan Gong et al. (2013): Ecological Modeling 263: 64-80
Ecological Modelling 263: 64-80 (2013)
Predicted changes in CO2 and CH4 balances of pristine Finnish peatlands
2000-2099: Regional modeling
- Generally CO2 sink will decrease,
less in the north, most in the
western part of Finland, there
the fens can turn a weak source
of CO2
- bogs are more sensitive than fens
Methane
- CH4 emissions increase in the
north but in the south there can
be decrease in the emissions,
especially in the west
- Fens are more sensitive than
bogs
Ca
rbo
n d
iox
ide
Me
than
e
Carbon dioxide
Nitrous oxide and boreal peatlands
Global Change Biology 5: 183-189 (1999)
Short-term response of nitrous oxide emissions to lowering of water table
of natural peatland Microcosm experiment
-100
0
100
200
300
400
500
600
700
800
900
1000
1 2 3 4 5 6 7 8 9 10
Natural
Drained for forestry
Minerotrophic Ombrotrophic
Nitrous oxide fluxes from natural peatland, and peatlands drained for forestry
Natural peatlands have low N2O emissions, they have even some N2O uptake (they act as a sink
for the atmospheric N2O). Why draining, i.e. lowering of water table by ditching, has minor effect
on N2O emissions from the ombrotrophic peatlands in contrast to the minerotrophic ones? The
peatlands below were drained 20-40 years before their N2O emissions were measured. Every
peatland has also a control sub-site without drainage (natural hydrology)
Martikainen et al (1993). Nature 366: 51-53 Regina et al. (1996) .Biogeochemistry 35: 401- 418
Maljanen et al. (2010). Biogeosciences 7: 2711-2736
Relationships between soil C to N ratio and N2O emissions in
manipulated organic soils
C/N
5 10 15 20 25 30 35 40N
2O
flu
x (
g m
-2 y
r-1)
0
1
2
3
4
5
6
forestrydrained
Agricullture
Afforested agriculture
peat extraction
Klemedtsson et al. (2005). Global Change Biology 11: 1142-1147
Forested organic soils
Possibilities to omit carbon loss (and N2O) from
peat soil used in agriculture depend on climatic
conditions
UOM
UM
IDF
GR B
A FAAB A
FREF
PE
RCG
REP
WR
g C
O2 e
q.
m-2
yr-1
0
250
500
750
1000
1250
n=14 n=39 n=40 n=10 n=5 n=3 n=6 n=12 n=2 n=16 n=1 n=6 n=11
CH4
UOM
UM
IDF
GR B
A FAAB A
FREF
PE
RCG
REP
WR
g C
O2 e
q.
m-2
yr-1
0
250
500
750
1000
1250
n=7 n=17 n=44 n=14 n=5 n=5 n=6 n=12 n=1 n=7 n=1 n=2 n=4
N2O
UOM
UM
IDF
GR BA FA AB AF
REF
PERCG
REP
WR
g C
O2 e
q.
m-2
yr-1
-1000
-500
0
500
1000
1500
2000
2500
3000
3500
n=6 n=16 n=1 n=4 n=3 n=3 n=5 n=1 n=2 n=16 n=1 n=6 n=12
CO2
UOM
UM
IDF
GR B
A FAAB A
FREF
PE
RCG
REP
WR
g C
O2 e
q.
m-2
yr-1
-1000
-500
0
500
1000
1500
2000
2500
3000
3500
TOT
UOM = undrained ombrotrophic peatlands UMI = undrained minerotrophic peatlands DF = ombrotrophic and minerotrophic sites drained for forestry GR = drained for agriculture – grass BA = agriculture – barley FA = agriculture – fallow AF = agriculture – afforested AB = agriculture –abandoned REF = forestry – restored PE = drained for peat extraction PEF = peat extraction – afforested RCG = abandoned peat extraction - cultivation of reed canary grass REP = drained for peat extraction – restored WR = water reservoirs A negative value indicates uptake by the ecosystem and a positive value net emission, n = number of sites, error bars indicate standard deviation between sites
Maljanen et al. (2010). Biogeosciences 7:
2711-2736.
Methane
Nitrous oxide
Carbon dioxide
All three greenhouse gases together
The mean values of reported annual net fluxes of CH4, N2O and CO2 exchange and the net effect
of these gases as g CO2 equivalents m-2 (Global Warming Potential, GWP 100-year time
horizon) from different peatland categories in the Nordic countries
Natural Forest. Agricultural Peat extraction Reservoirs
GCB Bioenergy 1: 35-50 (2009)
Wet Dry Dry Wet
Carbon balance component of a perennial crop (Phalaris arundinaceae)
cultivation on organic soil
Volatiles other than greenhouse gases
with atmospheric importance in changing
environment
Volatile organic carbon compounds (VOCs)
Nitrogenous compounds ?
Site
N1 N2 N3 D4 D5 D6 D7 U8 U9 U10 U11
NO
, N2O
, HO
NO
flux
rat
e (µ
g N
m-2
h-1
)
0,1
1
10
100
1000
10000
NO
N2O
HONO
* ** ***
C:N in soil 10 20 30 40 50 60
HO
NO
flu
x r
ate
(µg N
m-2 h
-1)
0
2
4
6
8
10
* * *
Recent findings: Emissions of nitrous acid (HONO) form boreal forests and
peatlands ; Peatlands with lowered water table are the most potential sources
HONO is an important source of OH radical, the key oxidizing agent in the atmosphere. Source of
HONO in soil is nitrite (NO2-). In acidic conditions nitrite is transformed chemically to volatile HONO.
HONO is associated to e.g. in fate of CH4 in the atmosphere because oxidation of CH4 by
OH radical Is the most important sink for CH4
Natural Drained Upland forests
peatlands peatlands
Soil Biology & Biochemistry 67: 94-97 (2013)
Some comments on the effects of
climate change on carbon and nitrogen
dynamics of Arctic peatlands
There is in the Arctic peatland elevation as a results of permafrost. This
affects the C and N dynamics
Seida (close to Vorkuta), Russia
Permafrost started to develope
in the region some 3500 years
ago
- Formation of elevated peat
plateaus (bogs)
Bog
Fen
Frozen thermokarst lake
Eroding peat walls, height
even several meters
Temperature Precipitation
Hydrology
(water table)
Biogeochemistry of peatlands
(Greenhouse gas fluxes)
Managements
Permafrost
melting
- Subsidence
Arctic peatlands
Stordalen mire, Abisko Northern
Sweden (Christensen et al. 2004)
Increase in mean T more than 1oC since
the early 80s
Thawing of sub-arctic permafrost has increased methane
emissions (landscape scale increase 22-66 % over the
period 1970 to 2000)
Vegetation distribution (Correlates with soil
moisture) Changes in methane emissions (mg CH4 m
-2 h-1)
(Not classified)
In Arctic elevated peatlands there
are natural hot spots for high N2O
emissions
Repo et al. (2009). Nature Geoscience Doi:10:1038/NGEO434
•.
Marushchak et al. (2011). Global Change Biology 17: 2601-2614
Concluding remarks
The CO2 fluxes can go to opposite direction than the CH4 dynamics with
climate change in boreal peatlands
There will be (and have been) differences in the carbon and nitrogen dynamics
between natural boreal and Arctic peatlands with changing climate.
The possible carbon losses from the Arctic soils as a result of melting permafrost
is under intensive discussion/studies. Also carbon sink capacity of boreal peatlands
can decrease with warming climate
In addition to greenhouse gas emissions the emissions of other volatile compounds
with atmospheric importance can be affected by climate change and peatland
managements
The climate change induced changes in local/regional gas dynamics of boreal
peatlands are likely less than the changes caused by intensive peat managements