Spatial and temporal variability of CO2 efflux of frozen ... · 12/5/2014  · Based on the regression analysis among more than 10 characteristics (hydrothermal, geocryological, soil)

Bobrik Anna*, Goncharova O., Matyshak G., Ryzhova I., Ponomareva O., Ogneva O.

Department of Soil Science, Lomonosov Moscow State University, Moscow, Russia, *[email protected]

Spatial and temporal variability of CO2 efflux of frozen peatland soils at fine scale (Russia, CALM SITE R1)

The main question

Research area is located on the north of

Western Siberia (Nadym District, Russia)

within the northern boundary of north taiga, in

the contour part of the 3rd lacustrine-fluvial

plain of the Nadym River. It’s zone of

discontinuous permafrost. It’s absent in

forest and present under peatlands.

Conclusion

•Unique Nadym site consists of different types of ecosystems

which function in different geocryological conditions. Permafrost-

affected soils are characterized by low biological activity.

•Active layer thickness and soil CO2 effluxes are characterized by

high spatial and low temporal variability.

•We consider the main factor which determine the soil carbon

efflux is the depth of permafrost table, it determines the type of

ecosystem in such transitional landscapes and organic matter

transformation processes.

•Underestimation of the spatial variability of soil and vegetation

cover in the region of discontinuous permafrost can lead to

substantial distortion of estimates of the total greenhouse gases

balance.

Research area

1-ha (100m*100m) grid (N65°20',

E72°55’) consists of a square array

of permanent stakes separated by

10 m (121 data points per grid for

all measurements). Permafrost is

closely associated with frozen

peatlands, bog and frost mounds.

The typical soils are Turbic Cryosol

of young frozen peatland and

Histosols of bog.

Key references 1) Goncharova, O.Yu., Matyshak, G.V., Bobrik, A.A., Moskalenko, N.G., 2014. Carbon

dioxide production by northern taiga soils of Western Siberia (Nadym site). Earth

Cryosphere, 18, 66–71, 2) Goncharova, O.Yu., Matyshak, G.V., Bobrik, A.A., Moskalenko,

N.G., 2015. Soils thermal regime in sporadic permafrost areas (Western Siberia, Russia).

Eurasian Soil Science, In Press.

m

%

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Frozen

peatland

Spatial and temporal variability of

permafrost table depth and carbon dioxide

efflux

mgСО2 m-2 h-1

Efflux of CO2

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Aug, 2013 Aug, 2014

Depth of permafrost

table

Based on the regression analysis among more than 10 characteristics

(hydrothermal, geocryological, soil) for CALM R1 site was revealed high

and significant correlation carbon dioxide efflux with microbial biomass

carbon in the upper 10 cm soil layer (beta=0,965; p-level<0,05) and

with the permafrost table depth (beta=0,333; p-level<0,05).

0

1

2

4

6

8

10

mg g -1 soil

MC, Aug 2013 0 10 20 30 40 50 60 70 80 90 100

0

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WEOC, Aug 2013 0

0.15

0.3

0.45

0.6

0.75

0.9

%, of TOC

6

11

16

21

26

31

36

41

46

TOC, Aug 2013

The values of microbial biomass are high, but geocryological and

hydrothermal conditions inhibit all soil biological processes. Permafrost-

affected soils of peatlands are characterized by the low biological

activity which leads to the preservation of organic matter, so these

ecosystems are the sink of carbon.

CALM landscape

0 10 20 30 40 50 60 70 80 90 100

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0.9

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0

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5

25

45

65

85

Relief

Bog

T1

B, BC

T2

T1

O

Volumetric soil moisture

content, Aug 2014

Active

laye

r P

erm

afr

ost

+ content of the total organic carbon (TOC),

carbon of water - extractable organic matter

(WEOC) (extraction of 0.005M K2SO4), carbon of

microbial biomass (MC) in the upper 10 cm of soil

(by chloroform fumigation–extraction (FE) method)

and common soil properties were analized in

laboratory

Regime monitoring of the carbon dioxide efflux

from the soil surface (close non-steady-state

non-through-flow chambers method)

Measurement

of active layer

thickness

The Circumpolar Active Layer Monitoring (CALM) program developed over the last

decade as a leading edge in comprehensive efforts to study the impacts of climate

change in permafrost environments. CALM sites are convenient for the study of

spatial and temporal variation of soil parameters at fine scales.

What does determine biological activity and function of permafrost-affected soils?

Mean= 0,27±0,05

%

m

Mean=135±35 Mean=145±25

Mean=61,70±20,50

Mean=124±10 Mean=115±15

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Mean=36,50±10,50

Mean=3,00±0,20

Properties of SOM Methods

Mean=0,54±0,20

CALM R1

+ regime monitoring of the temperature of air, soil surface and soil

(Thermochron iButtonTM ); description of soil and vegetation cover

There is significant intra site variation

in near-surface soil moisture content.

Soil moisture is strongly correlated with

relief (beta= -0,801; p-level<0,05).

Acknowledgments Financial support was provided

by the Russian Foundation for

Basic Research, grant RFBR

№13-04-01577 “Cryogenesis is

a subfactor of soil formation on

north of Western Siberia”.