Der Einuss verschiedener Vege- tationstypen auf Oberächen- temperaturen und Auftautiefen

Der Einuss verschiedener Vege- tationstypen auf Oberächen- temperaturen und Auftautiefen

Inge Grünberg und Julia Boike

Study sites

Data from Walker et al. (2005)

Kytalyk

I North-East Siberia I Low Arctic

I Annual temperature:

− 13

C

I Active layer thickness:

1555 cm

I Permafrost depth:

400600 m

Romanovskii et al. (2004); van Huissteden et al. (2005); van der Molen et al. (2007)

Study sites

Data from Walker et al. (2005)

Trail Valley Creek I North-West Canada I Low Arctic, tree line I Active layer thickness:

25100 cm I Permafrost depth:

100150 m

Marsh et al. (2008)

Modelling results from Kytalyk:

Vegetation climate relationship

Tusso cksedge

Dwarfshrub Lichen-rich

shrub Wet

sedge Drysedge

Peat moss Waterlogged

sedgeWater 0.05

0.1 0.15 0.2

Albedo

Reected

Absorbed by leaves

Absorbed by wood

Absorbed by background

0 1 2 3 4

0 0.2 0.4 0.6 0.8 1

Plant area (m²m⁻²)

Fraction

I Vegetation type aects all radiation budget components I High spatial variability

I Vegetation density aects energy partitioning

I Wood plays a major part

Juszaketal.(2017) Juszaketal.(2014)

Modelling results from Kytalyk:

Vegetation climate relationship

Tusso cksedge

Dwarfshrub Lichen-rich

shrub Wet

sedge Drysedge

Peat moss Waterlogged

sedgeWater 0.05

0.1 0.15 0.2

Albedo

Reected

Absorbed by leaves

Absorbed by wood

Absorbed by background

0 1 2 3 4

0 0.2 0.4 0.6 0.8 1

Plant area (m²m⁻²)

Fraction

I Vegetation type aects all radiation budget components I High spatial variability

I Vegetation density aects energy partitioning

I Wood plays a major part

Juszaketal.(2017) Juszaketal.(2014)

Field measurements in Kytalyk:

Climate permafrost relationship

0 0.2 0.4

20 40

Transmittance

Activelayerthickness(cm)

0.06 0.08 0.1

Reectance Dwarf shrubs

Wet sedges

I Systematic dierence

between vegetation types I No relationship within a

single type

I Other drivers may be more important I Soil moisture, snow, &

evapotranspiration

Field measurements in Trail Valley Creek

I Covering dierent

vegetation types

I Survey in thaw slumps

Field measurements in Trail Valley Creek

I Vegetation: species, height

I Climate: radiation, surface temperature I Soil: thaw depth, thermal

properties, temperature,

heat ux

Field measurements in Trail Valley Creek

I Vegetation: species, height

I Climate: radiation, surface temperature

I Soil: thaw depth, thermal

properties, temperature,

heat ux

Field measurements in Trail Valley Creek

I Vegetation: species, height

I Climate: radiation, surface temperature I Soil: thaw depth, thermal

properties, temperature,

heat ux

Field measurements in Trail Valley Creek:

Thaw slump characteristics

Slump Reference

Aboveslump 2

4 6 8 10

Soiltemperature(◦C)

Slump Reference

Aboveslump 0

20 40

Soilmoisture(%)

I Slumps are wet and warm

Field measurements in Trail Valley Creek:

Thaw slump characteristics

Slump Reference

Aboveslump 20

40 60 80 100

Activelayerthickness(cm)

I Slumps thaw

Field measurements in Trail Valley Creek:

Vegetation climate relationship

0 50 100 150

0.1 0.15 0.2

Mean veg. height (cm)

Albedo

0 50 100 150

0.2 0.4 0.6 0.8 1

Mean veg. height (cm)

Transmittance

I Lowest albedo at water logged conditions

I Vegetation shades the soil

Field measurements in Trail Valley Creek:

Climate permafrost relationship

0.1 0.15 0.2

40 60 80 100

Albedo

Activelayerthickness(cm)

0.2 0.4 0.6 0.8 1 40

60 80 100

Transmittance

Activelayerthickness(cm)

I Apparently no connection

I Conrms the (no-)result from Kytalyk

Field measurements in Trail Valley Creek:

Soil surface temperature

08.2016 12.2016 04.2017 08.2017 12.2017 04.2018

−10 0 10 20 30

Soiltemperature(◦C)

Lichen Tussock Dwarf shrub Tall shrub

Field measurements in Trail Valley Creek:

Soil surface temperature

Lichen Tussock Dwarfshrub

Tallshrub

−10

−8

−6

−4

TmedianFebruary(◦C)

Lichen Tussock Dwarfshrub

Tallshrub 15

20

TmedianJuly(◦C)

I Tall shrub soil is warmest in winter and coldest in summer

I Lichen tundra has the strongest annual (and diel) variation

Field measurements in Trail Valley Creek:

Soil surface temperature

25.04 30.04 05.05 10.05 15.05 20.05 25.05 30.05 04.06

−10 0 10

Soiltemperature(◦C)

Lichen Tussock Dwarf shrub Tall shrub

I Tall shrubs collect snow

I Lichen and dwarf shrub tundra are similar

Thanks to

I Julia Boike

I MOSES team: Stephan Lange, Bill Cable I TVC team: Phil Marsh

I University of Zurich: Gabriela Schaepman-Strub, Maitane

Iturrate-Garcia

Literature

van Huissteden, J., et al. (2005), Journal of Geophysical Research:

Biogeosciences, 110(G2): G02002.

Juszak, I., et al. (2014), Remote Sensing of Environment, 153: 7989.

Juszak, I., et al. (2017), Remote Sensing of Environment, 193: 86102.

Marsh, P., et al. (2008), Snowmelt Processes and Runo at the Arctic Treeline:

Ten Years of MAGS Research, 97123, Springer Berlin Heidelberg, Berlin, Heidelberg.

van der Molen, M. K., et al. (2007), Biogeosciences, 4(6): 9851003.

Romanovskii, N. N., et al. (2004), Quaternary Science Reviews, 23(1113):

13591369.

Walker, D. A., et al. (2005), Journal of Vegetation Science, 16(3): 267282.