pertti martikainen, greenhouse gas dynamics of northern peatlands

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


Hydrology

(water table)



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


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

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


Hydrology

(water table)



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

pertti martikainen, greenhouse gas dynamics of northern peatlands

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