State Water Resources Research Institute Program

Project Id: 2010AK86B
Title:Contribution of Permafrost Degradation to Shrub Expansion in Arctic Alaska
Project Type: Research
Start Date: 3/01/2010
End Date: 2/28/2011
Congressional District: AK-001
Focus Categories: Hydrology, Climatological Processes, Ecology
Keywords: permafrost, shrubs, ecology, arctic, cores
Principal Investigators: Nolan, Matthew A; Tape, Ken
Federal Funds: $ 4,000
Non-Federal Matching Funds: $ 1,900
Abstract: Climate warming is directly or indirectly responsible for a widespread expansion of shrubs in the arctic tundra over the last half-century (Figure 1)(Tape et al. 2006), but the causes and timing of this expansion are poorly understood and documented. Climate warming in the arctic has also apparently led to permafrost degradation over the same time interval (Gooseff et al. 2009, Lantz and Kokelj 2008). Our hypothesis is that permafrost degradation has led to an increase in catastrophic and gradual down-slope soil movement which may have facilitated a heightened disturbance regime, which could be an indirect mechanism responsible for much of the shrub expansion currently underway in the arctic. We are proposing to test this hypothesis by examining lake-sediment cores in catchments where shrub expansion has been identified. Using sediment flux into the lakes as a proxy for down-slope soil movement (Huang and O'Connell 2000) and permafrost degradation, sedimentation rates since the mid-19th century will be quantified using 210Pb and 137Cs dating, which provide the decadal resolution necessary to test the hypothesis. The shallow sediment lake cores have already been acquired. Support is requested to date the cores to examine how depositional rate has changed over the last 150 years.

Progress/Completion Report, 2010, PDF

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