METHODS The Anaktuvuk River Fire occurred in 2007 on the North Slope of Alaska. In 2008, three eddy covariance towers were established at sites representing unburned tundra, moderately burned tundra, and severely burned tundra. Eriophorum vaginatum flowers were counted from annual photographs of each site during peak flowering season (6/17-7/20). Photographs were taken with either a tower mounted digital camera that was set to acquire an image per day during the growing season, or from personal photographs of the site in years were the camera malfunctioned. For each photograph, 50 individual tussocks were identified and visual counts of the flowers for each tussock were recorded. Pairwise T-tests were used to determine differences in flowers per tussock among sites in each year.
Findings: Fire increased flowers per tussock in all years except for the first post-fire growing season (2008). There were no signs of flowers at the burn sites in 2008. Flowering at the unburned site exhibited interannual variability ranging from ~7 to 21 flowers per tussock with high flowering events in 2008, and 2012. On average, flowers were 3 times more abundant at the burn sites from 2009-2014. Flower abundance also differed among burn sites with the severe burn having ~1.4 to 1.9 times more flowers per tussock than the moderate burn in 2012 and 2013. Flower abundance did not significantly differ between the severe and moderate burn sites in the other years.
Note: We have data on tussock density at the site, so can convert data to flowers m-2. These patterns are consistent with Wein 1973 and Bret-Harte 2008 who found higher flowering in tundra fire scars several years after fire (see image below).
FOR MORE INFORMATION CONTACT: Gus Shaver, The Ecosystems Center, Woods Hole, MA, 02543, USA FORMAT OF DATA FILE: ASCIIReferences:Rocha, A.V. and G.R. Shaver (2011) Burn severity influences post-fire CO2 exchange in arctic tundra. Ecological Applications. 21:2, 477-489, doi:10.1890/10-0255.Rocha, A.V. and G.R. Shaver (2011) Postfire energy exchange in arctic tundra: the importance and climatic implications of burn severity. Global Change Biology. doi:10.1111/j.1365-2486.2011.02441.x. 

See Methods