Effects of Disturbances on Vegetation Composition and Thaw in Boreal Forests and Ecosystems of the Siberian Arctic Erika Ramos1, Heather D. Alexander1, and Susan Natali2 1University of Texas - Brownsville, 2Woods Hole Research Center Background Study Sites Vegetation Cover Conclusion

• Climate-driven changes to Bare Ground Evergreen Deciduous / Grass Other Arctic Ocean the thermal regime of permafrost have the Disturbed Cherskii Tundra

potential to create surface Tundra disturbances that influence Undisturbed Russia Tundra vegetation dynamics and

underlying properties. Disturbed

Forest

Boreal

Forest Boreal

• These changes are Undisturbed

Forest Boreal particularly important • These results highlight important in , ice-rich • The sites were located near the Northeast 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% linkages between disturbances, permafrost which is Science Station (NESS) in Cherskii, Russia. • Both and frost boils resulted in decreased vegetation cover vegetation communities, and common across large areas and greater exposure of mineral soils. permafrost soils, and contribute to of the Siberian Arctic. Arctic Ocean • Disturbed locations showed a significant decrease in shrub cover and an our understanding of how changes in increase in bare ground. Arctic vegetation dynamics as direct • Vegetation and the accumulation of soil organic and/or indirect consequences of matter drive ecosystem (C) dynamics and climate change have the potential to contribute to the insulation of soils and protection Soil Temperature & Thaw Depth impact permafrost C pools. of permafrost from thaw. Tundra 14 70 Undisturbed Undisturbed 12 Disturbed 60 Disturbed Future Work 10 50 Objective Cherskii 8 40 NESS • Examine the effects Duvanny Yar 6 30 of two disturbance

4 20 Thaw Depth (cm) Depth Thaw

types—thermokarst (˚C) Temperature Soil and frost boils—to 2 10 determine 0 0 Thermokarst: Boreal Frost Boils: Tundra Thermokarst: Boreal Frost Boils: Tundra disturbance effects Forest Forest on the vegetation Methods Location Location community and soil • Observe and measure the effects of properties. • 2-3 times higher soil temperature and deeper thaw depth in disturbed vs undisturbed sites. fire as a disturbance on boreal forest larch stands. Disturbances Soil Moisture Acknowledgements • Upwellings of soil due 0.7

to . Northeast Science Station • Grid point vegetation measurements in both 0.6 Frost Boils disturbed and undisturbed sites. Undisturbed 0.5 Disturbed

0.4 • This work was made possible by the National Science Foundation 0.3 (OPP:1304040, 1044610), The Polaris Thermokarst 0.2 Project and The Northeast Science Soil Moisture (m3/m3) Moisture Soil Station. Thanks to the 2014 Polaris • As soil thaws it starts to 0.1 Project co-participants: Homero Pena, subside causing it to Jessica Eason and Mckenzie Kuhn as cave in on itself. 0 Thermokarst: Boreal Forest Frost Boils: Tundra well as Polaris PI’s, John Schade, John • I sampled disturbed and undisturbed areas in • Soil temperature, moisture and thaw depth were Location Wood and Mike Loranty, for their two thermokarst locations in boreal forests and measured in disturbed as well as adjacent • Soil moisture was 3-4 times higher in thermokarst areas but 1.2-2 times advice and input. Photographs by Chris two locations in tundra undisturbed sites. lower in frost boil areas. Linder.