This week, EEB welcomes PhD candidate Casper Christiansen of the Queen’s Department of Biology and graduate of the University of Copenhagen, Denmark, who will present:
How do seasonal climatic changes affect litter and soil carbon and nutrient cycling in arctic tundra ecosystems?
Climate change is leading to warmer temperatures and greater snowfall in Arctic regions. Microbial decomposition activities are strongly regulated by temperature, and climate warming is therefore projected to enhance decay of the vast tundra soil organic matter pool, releasing CO2 into the atmosphere and nutrients into the soil solution. By contrast, increased soil nutrient availability promotes plant growth and changes in vegetation, both of which may enhance plant uptake of CO2 from the atmosphere. Consequently, depending on the net balance between these increases in CO2 release and uptake, tundra ecosystems may end up contributing globally significant feedbacks to a changing climate, further exacerbating environmental change.
In my thesis work, I investigated how short- (1 year) and longer-term (up to 9 years) experimentally deepened winter snow and summer warming may impact tundra biogeochemical cycling (i.e. litter decomposition rates, plant and soil carbon storage, and microbial communities) using experimental plots located in distinct ecosystems across the Canadian, Greenlandic, and Norwegian arctic.
Here, I will primarily – but not exclusively – focus on some of the surprising results from our long-term deepened snow manipulation plots near Daring Lake, NWT, most of which contrast with observations from short-term studies. Our results suggest that despite extremely cold temperatures, changes in winter climate are likely to have significant immediate and legacy effects in tundra ecosystems, and that climatic changes in winter may have much greater impact on annual carbon balance in mesic tundra than otherwise thought.
This EEB Seminar, will run at a special time on Thursday from 11:30-12:30pm, in the EEB Lounge of the
BioSciences Complex, Room 4338. Light refreshments are served starting at 11:15.