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(1)

A Late Holocene palaeoenvironmental lake record from the Yukon Coastal Plain, NW

Canada

Wolter, J., Herzschuh, U., Lantuit, H.

(2)

High resolution palaeoecological record of the last centuries in the subarctic

tundra of NW Canada

• Little Ice Age

• Recent warming

Aim

(3)

Study area

Herschel Island

Beaufort Sea

(4)

The Yukon Coastal Plain

Subarctic

(5)

Subarctic

Treeless tundra Arctic Ocean

British Mountains

The Yukon Coastal Plain

(6)

Continuous permafrost

Unconsolidated sediments

The Yukon Coastal Plain

Subarctic

Treeless tundra Arctic Ocean

British Mountains

(7)
(8)

Tussock tundra

• Eriophorum tussocks

• Dwarf shrubs (Betula glandulosa, Salix sp., Ericales, Rubus

chamaemorus, Dryas integrifolia)

• Mosses

(9)

Lake-shore vegetation

• Shrubs

• Forbs (Chrysosplenium, Petasites, Polygonum, Ranunculus, Rumex, Stellaria,..)

• Cyperaceae (Carex, Eriophorum)

• Grasses (Poa, Arctagrostis, Hierochloë)

• Mosses

(10)

Ice-wedge polygons (mires)

• Cyperaceae (Carex, Eriophorum)

• Mosses

• Dwarf shrubs (Salix, Betula, Ericales,

Rubus chamaemorus, Dryas integrifolia)

(11)

Lake sediment short core (49 cm)

Biogeochemistry: TC, TOC, TN, δ13C

Grain size distribution

Geochronology:

210Pb/137Cs, AMS 14C

Pollen Methods

(12)

Results

(13)

Results

No significant splits

(14)

Results

No significant splits

(15)

Results

No significant splits

(16)

Results

No significant splits

(17)

Results

Lake signal

Lake marginal vegetation signal

(18)

Results – oscillating lake water level

2012

Pre 1900 Change in water level

(draining and refilling)

Change in basin depth (thermokarst)

(19)

Results – oscillating lake water level

2012

Pre 1900 Change in water level

(draining and refilling)

Change in basin depth (thermokarst)

(20)

• Little Ice Age ?

• Recent warming?

(21)

Burn and Zhang 2009

Herschel Island (Yukon Coast)

1899-1905 compared to 1999-2005:

MAAT +2.6°C MJanT +5.8°C

(22)

Burn and Zhang 2009

Herschel Island (Yukon Coast)

1899-1905 compared to 1999-2005:

MAAT +2.6°C MJanT +5.8°C

(23)

Fraser et al. 2012

(24)
(25)

Conclusions

• No regional vegetation change during the last 300 years

• Slight increase in Alnus pollen in the last century – approaching Alnus shrubline

• Local hydrological change: lower and variable lake water level pre 1900

(26)

Thank you for your attention!

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