Impacts of Arctic Tundra Wildfires on Carbon Cycling Mack MC, Bret-Harte MS, Hollingsworth TN, Jandt RR, Schuur EAG, Shaver GR, Verbyla DL (2011) Carbon loss from an unprecedented Arctic tundra wildfire. Nature 475:489-492. by Catherine Deschenes Overview 1. Case 2. Methods 3. Results 4. Global Connection 5. Ecosystem Connection 6. Human Connection 7. Take Home ACIA (2004) Anaktuvuk River Fire, Alaska Bureau of Land Management, Alaska Fire Service (2007) 1039 2 km Area burned during the fire, doubling the total burned area in the region since 1950 Suppl. Figure 1 (large) Suppl. Figure 3 (small) FOCUS: ➢2008 field campaign to evaluate C and N released from plant and soil of moist acidic tundra ecosystems during the fire. Methods Tundra soil profile Typical soil profile in wet tundra. (2010) State of Alaska Division of Spill Prevention and Response. Eriophorum vaginatum Suppl. Fig. 4 C, D, B, A (clockwise from top left) Field Sampling Methods 20 burned sites 11 unburned reference sites Suppl. Fig. 5 Carbon Dating Figure 1 Results 31% (+/-3%) loss of combustible C 5X the annual NPP of moist Arctic tundra 2.1 Tg C released in atmosphere → Similar in magnitude to annual net C sink for entire Arctic tundra biome (avg of last 25 years) → Extrapolation from MAT ecosystem (54% of burn area) ~21% loss of combustible N 400 years of N accumulation NASA Langley Research Center M. Ewert 30% (+/-3%) decrease in soil organic layer Burning restricted to soil surface So what? : Global Connection Carbon Arctic 100 Pg carbon Native Americans: Arctic culture area. Britannica Online for Kids. 496 Pg carbon Wikipedia Commons Removal of organic layer: 1. Loss of permafrost insulation 2. Thawing 3. Deep C release 4. Altered ecosystem C Decreased albedo by 50balance Increased ground heat 71% flux + + → Suppl. Fig. 4C, D Lower Albedo= Permafrost thawing= methane+carbon dioxide So what? : Ecosystem Connection Arctic fire VS other climate-driven C loss pathways 30-50X more rapid (+amplification of pathways?) Ground subsidence Neil Shubin Stimulation of microbial activity Jenny E. Ross/Corbis (2009) USGS Alaska Science Center Stimulation of soil decomposition Net C transfer into the atmosphere= warming ➔ Young soil lost+high grass survivorship = renewal of topsoil lost ➔ Shift to early-successional ecosystems with low C storage Recovery Scenario 1 Shorter fire regime (80-150 yrs) Positive feedback to climate warming ➔ Shrubs have lower albedo Grasses die, shrubs prevail ➔ Shrubs have higher productivity and biomass, and lower soil C stocks (inefficient C sinks) Arctic fire rapid offset of greening through release of deep permafrost C pools VS Arctic greening (-’ve feedback to global warming) graminoid (grass) tundra → shrub tundra or boreal forest Scott Goetz, Pieter Beck, and Kevin Guay, Woods Hole Research Center Who cares? : Human Connection The global community (all of us!) Northern communities (some Canadians) ➔ Air quality ➔ Physical danger ➔ Local economy ➔ Ecosystem imbalance ➔ Local climate warming ➔ Subsidence amplification(?) ➔ Global climate warming amplification (impacts on economy, populations, food supply, ecosystem imbalances, etc.) Take Home ➢The Anaktuvuk River Fire is a manifestation of an increasing fire regime in the Arctic tundra. ➢Arctic tundra wildfires release significant amounts of young topsoil carbon and nitrogen, decrease tundra albedo while increasing ground heat flux and facilitating permafrost thawing (which releases CH4 and CO2). ➢Impact: Rapid C loss in the Arctic ground goes into the atmosphere, causing positive feedback for local and global climate warming. Thank you! Questions? Photo Sources ACIA. (2004) Carbon cycle in the Arctic. Retrieved from http://www.xplora.org/downloads/Knoppix/ESPERE/ESPEREdez05/ESPEREde/www.atmosphere.mpg.de/enid/0,55a304092d09/Zukunft_der_Arktis/Leben_in_der_Arktis_3 w0.html. Britannica Online for Kids. Native Americans: Arctic culture area. [Map/Still]. Retrieved from http://kids.britannica.com/elementary/art-192332. Bureau of Land Management, Alaska Fire Service. (2007) Anaktuvuk River Fire. Retrieved from http://hermes.mbl.edu/news/features/anaktuvuk.html. Compass: http://www.clipartbest.com/cliparts/ncX/8oo/ncX8ooecB.png Ecocem Ireland Ltd. Albedo diagram [graphic]. Retrieved from http://www.ecocem.ie/index.php?p=environmental&q=albedo. Jenny E. Ross/Corbis. (2009) Thawing permafrost on the tundra of Wrangel Island. Retrieved from https://www.newscientist.com/article/dn27420-microbes-play-villainousrole-in-arctic-climate-change/. M. Ewert. Tundra. Retrieved from https://www.flickr.com/photos/mewerts/4680757869/sizes/l/in/photostream/. NASA Langley Research Center. Boreal Forest Fire. Retrieved from http://www.colorado.edu/geography/blanken/GEOG%206181%20Fall%202003/rech/pages/fire2.gif. Native Americans: Arctic culture area. [Map/Still]. In Britannica Online for Kids. Retrieved from http://kids.britannica.com/elementary/art-192332 Neil Shubin (photographer). Arctic Bone Nurseries. Retrieved from http://static1.squarespace.com/static/544591e6e4b0135285aeb5b6/t/566aee0240667acc25b71f0c/1449848323270/. Scott Goetz, Pieter Beck, and Kevin Guay, Woods Hole Research Center[data graphic]. Greening of the Arctic. Retrieved from http://www.amnh.org/explore/sciencebulletins/bio/visualizations/greening-of-the-arctic/dataset-information. State of Alaska Division of Spill Prevention and Response. (2010) Typical soil profile in wet tundra. Retrieved from https://dec.alaska.gov/spar/ppr/r_d/ttman/images/P-2-webimages/soil_profile_wet_sedge_opt_500.jpeg. USGS Alaska Science Center. Arctic ground subsidence. Retrieved from http://eros.usgs.gov/lir/changing-arctic-ecosystems-mapping-long-term-changes-vegetationimportant-migratory-birds-and.