Effects of Disturbances on Vegetation Composition and Permafrost Thaw in Boreal Forests and Tundra Ecosystems of the Siberian Arctic

• Climate-driven changes to the thermal regime of permafrost soils have the potential to create surface disturbances that influence vegetation dynamics and underlying soil properties.

• These changes are particularly important in yedoma, ice-rich permafrost which is common across large areas of the Siberian Arctic.

Objective

Vegetation Cover

Disturbances Soil Moisture

Methods

Background Conclusion

Future Work

Northeast Science Station

Erika Ramos1, Heather D. Alexander1, and Susan Natali21University of Texas - Brownsville, 2Woods Hole Research Center

• Both thermokarst and frost boils resulted in decreased vegetation cover and greater exposure of mineral soils.

• Disturbed locations showed a significant decrease in shrub cover and an increase in bare ground.

• Observe and measure the effects of fire as a disturbance on boreal forest

larch stands.

Acknowledgements

• Examine the effects of two disturbance types—thermokarstand frost boils—to determine disturbance effects on the vegetation community and soil properties.

• As soil thaws it starts to subside causing it to cave in on itself.

• Upwellings of soil due to cryoturbation.

Duvanny Yar

Cherskii

Tundra

Arctic Ocean

• These results highlight important linkages between disturbances, vegetation communities, and permafrost soils, and contribute to our understanding of how changes in Arctic vegetation dynamics as direct and/or indirect consequences of climate change have the potential to impact permafrost C pools. Soil Temperature & Thaw Depth

• 2-3 times higher soil temperature and deeper thaw depth in disturbed vs undisturbed sites.

• Grid point vegetation measurements in both disturbed and undisturbed sites.

• Soil temperature, moisture and thaw depth were measured in disturbed as well as adjacent

undisturbed sites.• Soil moisture was 3-4 times higher in thermokarst areas but 1.2-2 times

lower in frost boil areas.

• This work was made possible by the National Science Foundation (OPP:1304040, 1044610), The Polaris Project and The Northeast Science Station. Thanks to the 2014 Polaris Project co-participants: Homero Pena, Jessica Eason and Mckenzie Kuhn as well as Polaris PI’s, John Schade, John Wood and Mike Loranty, for their advice and input. Photographs by Chris Linder.

Study Sites

Russia Alaska

Arctic Ocean

Cherskii

• The sites were located near the Northeast Science Station (NESS) in Cherskii, Russia.

NESS

• I sampled disturbed and undisturbed areas in two thermokarst locations in boreal forests and two frost boil locations in tundra

Frost Boils

Thermokarst

• Vegetation and the accumulation of soil organic matter drive ecosystem carbon (C) dynamics and contribute to the insulation of soils and protection of permafrost from thaw.

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