Ninth International Conference on Permafrost ... - IARC Research

Ni n t h In t e r n at i o n a l Co n f e r e n c e o n Pe r m a f r o s tof high burn severity. This is attributed to either the lossand/or depletion of the insolating vegetation that providedprotection from incoming solar radiation and preventedevaporation, or to an increase in the active layer thicknesswhich results in more lateral and vertical drainage, and/or thermokarsting. The period 5–15 years following a fireshowing little variability in surface area are likely attributedto seasonal refreezing of the active layer. Refreezing of theactive layer prevents drainage and talik expansion, thusstabilizing ponds and minimizing changes attributed to firedisturbance. The mechanisms responsible for shrinkingduring long-term (15–25 years) periods is attributed to amore developed deciduous vegetation community withhigher evapotranspiration (ET) flux and reduced levels ofmoisture availability.Results from our pilot study in the Yukon Flats revealevidence that our methodology is capable of attainingdesired observations. Even though parameters such as lakedepth and permafrost abundance are not quantifiable usingthis method, we are confident that examining our other studyregions will allow us to anticipate changes as a result of fire.Further analysis will include remaining study areas, andresults will be presented during the NICOP.AcknowledgmentsThis project was funded through support from theBonanza Creek LTER (Long-Term Ecological Research)program (funded jointly by NSF grant DEB-0423442 andUSDA Forest Service, Pacific Northwest Research Stationgrant PNW01-JV11261952-231). The authors would like tothank the U.S. Fish & Wildlife service for their assistancein the acquisition of Landsat scenes, as well as the BLMand Alaska Fire Service for providing readily accessible firehistory data.ReferencesBurn, C.R. 1998. The response (1958–1997) of permafrostand near-surface ground temperatures to forest fire,Takhini River Valley, southern Yukon Territory.Canadian Journal of Earth Sciences 35(2): 184-189.Ishikawa, M. 2008. Heat and water processes of burned andunburned active layer. Presented at the IARC-JAXACollaborative Research Plan, University of AlaskaFairbanks, 28 February 2008.Liljedahl, A., Hinzman, L., Busey, R. & Yoshikawa, K.2007. Physical short-term changes after a tussocktundra fire, Seward Peninsula, Alaska. Journal ofGeophysical Research 112: F02S07.Riordan, B., Verbyla, D. & McGuire, A.D. 2006. Shrinkingponds in subarctic Alaska based on 1950–2002remotely sensed images. Journal of GeophysicalResearch 111: G04002.Yoshikawa, K., Bolton W.R., Romanovsky V.E., Fukuda, M.& Hinzman, L.D. 2002. Impacts of wildfire on thepermafrost in the boreal forests of Interior Alaska.Journal of Geophysical Research 107: 8148.4