INFLUENCE OF GROUND WATER TABLE DEPTH ON METHANE EMISSIONS FROM

TREE STEMS IN A FORESTRY-DRAINED FENMARI PIHLATIE1, IIKKA HAIKARAINEN1, ELISA HALMEENMÄKI1, PETTERI

PYYKKÖ1, KATERINA MACHACOVA2, MIKA KORKIAKOSKI3, KARI MINKKINEN4, PAAVO OJANEN5, TIMO PENTTILÄ5, ANNALEA LOHILA3

1University of Helsinki, Department of Physics, 2Global Change Research Centre, Brno, Czech Republic

3Finnish Meteorological Institute, Helsinki, Finland,4University of Helsinki, Department of Forest Sciences,

5Natural Resources Institute Finland.

Upland forest are a sink of CH4 (methanotrophs)

Despite this, above canopy fluxes show CH4 emissions.

Can trees be the missing source?

MOTIVATION

Among the natural sources, the contribution of vegetation to the global CH4 budget is the least

well understood (Carmischael et al., 2014).

CAN PINE TREES BE THE MISSING SOURCE OF CH4?

Dry upland soil Machacova et al. (2016), Scientific Reports.

What controls tree-CH4 emissions?

H1: Stem emissions depend on soil water content

HIGH STEM CH4 EMISSIONS FROM BIRCH IN WETCONDITIONS

Poster, Halmeenmäki et al.

Birch trees as conduits for CH4 produced in the soil?

Pangala et al. (2013): similar flux rates from wetland trees in Southeast Asia

FIELD EXPERIMENT: THE EFFECT OF GROUNDWATER TABLE ON TREE AND SOIL CH4 EXCHANGE

CH4

CH4

CH4

Water table

CH4

production transport

Partial cut: Letto 1Control: Letto 2

CH4

Pine, spruce, birch Spruce, birch

canopy transpiration↓

Lettosuo: Drained peatland forest

CH4 FLUX MEASUREMENTS

Manual stem chambers (UGGA, ultraportable greenhouse gas analyzer, LGR)- 5 chambers / tree species / siteAutomatic soil chambers (Picarro G1130) - 6 automatic chambers / site

Stem chamber profiles- 3 chamber heights / tree(birch)

June-August 2016

1.8.2016

SIGNIFICANT SOIL UPTAKEHIGHERCH4 UPTAKE FROMTHE CONTROL AREA

Partial cut, WT 10cm higher

SMALL STEM EMISSIONS BIRCHFROM PARTIALLY CUTFOREST

SMALL STEM EMISSIONS SPRUCE

FROM PARTIALLY CUTFOREST

BIRCH AND SPRUCE STEMFLUXES DIFFER IN HEIGHT

R1 R2 R3

B. pubescens , MkK

CH

4 -

flux

gh

1m

2

0

20

40

60

80

10099

0.88 0.31

R1 R2 R3

P. abies , MkK

-0.5

0.0

0.5

1.0

1.5

0.52

-0.14

1.1

R1 R2 R3

B. pendula , VT

-8

-6

-4

-2

0

2

4

6

-7.3

-1.6

4.5

Wet soil

Haikarainen et al., in preparation

R1 R2 R3

B. pubescens , MkK

CH

4 -

flux

gh

1m

2

0

20

40

60

80

10099

0.88 0.31

R1 R2 R3

P. abies , MkK

-0.5

0.0

0.5

1.0

1.5

0.52

-0.14

1.1

R1 R2 R3

B. pendula , VT

-8

-6

-4

-2

0

2

4

6

-7.3

-1.6

4.5

BIRCH AND SPRUCE STEMFLUXES DIFFER IN HEIGHT

Wet soil Wet soil

Haikarainen et al., in preparation

TAKE HOME AND FUTURE PLANSWe are not talking about teragrams of CH4 from boreal trees, but about a significantlydecreased CH4 sink=> global importance!

More measurements are neededto understand the mechanismsand drivers of CH4 emissions fromtrees => for modelling

Our measurements continueincluding seach for methanogensand methanotrophs, and study of tree anatomical differences

THANK YOU!

The Emil Aaltonen

Foundation