PARENT SESSION
Poster Session 6: Arctic and Alpine Ecology
Tuesday, August 9, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Landscape patterns of fire and plant succession in a boreal peatland landscape in northern Manitoba, Canada.

Camill, Phil^*,1, Barry, Ann¹, Moler, Jon ¹, Williams, Evie¹, ¹ Carleton College, Northfield, MN, USA

ABSTRACT- Long-term interactions among plant succession, fire, and carbon accumulation are poorly known in boreal and Arctic peatlands despite the potential importance of these processes in global climate change and carbon cycling. Peatlands underlain with permafrost are elevated above the regional water table, are relatively dry, and are dominated by Picea-feathermoss vegetation. They may be more prone to fire and may accumulate less carbon compared to wetter, unfrozen peatlands. Therefore, successional history and landscape pattern of peatland landforms may strongly control fire and carbon accumulation depending on whether more flammable permafrost plateaus are isolated or connected in large peatland landscapes. To test these hypotheses, we collected 17 peat cores, ranging in depth from 1.0-4.2 m, from permafrost plateaus located in a large peatland landscape in northern Manitoba, Canada. Cores were distributed across multiple spatial scales (10-50m, 400-700 m, > 1 km) to examine the patchiness of plant succession, fire, and carbon accumulation. In each core, we quantified fire severity (mm² charcoal area cc^-1 sediment) and broad peatland community types (frozen Picea plateau bog, unfrozen bog, unfrozen fen) using plant macrofossils. Soil carbon accumulation was not completed for this analysis. Several patterns emerged from these analyses. First, fires were uncommon in this peatland landscape, generally averaging 1-4 events over the last 8000 years. Second, distinct local fires (>50 mm²cc^-1) tended to be more common in recent sediments corresponding to permafrost plateau vegetation. Fires were rare in deeper sediments when the landscape was dominated by unfrozen bogs and fens. Third, the distribution of charcoal peaks was similar across cores at small spatial scales (< 100m) but less similar at large spatial scales (> 1km). These results suggest that fire is more prominent in dry, elevated peatlands underlain with permafrost and that the spatial isolation of permafrost plateaus in a matrix of unfrozen bogs and fens makes fire patchy at the landscape scale.

Key words: peatland, boreal, fire, paleoecology