Dr. Carissa Brown, Postdoctoral Researcher at the University of Sherbrooke, joined us for a webinar on February 23, 2012 (11:00 am to noon AKST) entitled 'Once burned, twice shy: Repeat fires result in black spruce regeneration failure.' Dr. Brown is currently studying plant species and communities at the edge of their range, focusing on the direct and indirect effects of climate change on species distribution at northern latitudes. Most recently, her work has focused on the responses to altered fire frequency at the northern margin of the boreal forest, particularly in black spruce forests. This month's webinar will discuss the latest findings on the impacts of 'repeat burns'. In summary: In sub-arctic boreal forests of the Yukon, closely timed fires have resulted in a black spruce regeneration failure. Using a natural field experiment, we demonstrated that this failure was due to an interruption to black spruce's serotinous regeneration strategy. The indirect climate effects caused by a change to the disturbance regime may initiate vegetation shifts of a larger magnitude or opposite direction than would happen due to climatic change alone, which is counter-intuitive to our current predictions regarding climate warming effects on the northern margin of the boreal forest. Instead of the predicted stand in-filling and tree range expansion, changes in disturbance regime may initiate the local degradation of treeline forest.