Peatlands and the global carbon cycle

Background/Question/Methods

The peatlands of the high latitude north contain vast reservoirs of carbon, whose potential importance to planetary metabolism was first emphasized by Eville Gorham in a series of classic papers in the 1980s and 1990s.  Northern peat lands have accumulated carbon, mainly in detrital forms, preserved by acidic, anaerobic and permafrost-related processes.  The areas covered by northern peatlands are vast, yet conditions and processes within the diverse ecosystems vary dramatically at very fine scales, creating multiple scales of pattern and complicating measurement and experimentation. Much of what we know about rates of carbon accumulation and loss in these ecosystems is based on paleoanalysis, yet today conditions are changing at unprecedented rates leading to no-analog conditions.  Predicting how peatlands will respond to global climate changes requires understanding how the diverse elements of this fine-scaled landscape will respond to change.  This is not a conceptual problem so much as it is a challenge to today’s observational and experimental techniques. 

Results/Conclusions

New methodology is however allowing us to assess ecosystem response to change at multiple scales, in a way that allows for assessing the consistency of explanation across scales.  Carbon dioxide and other trace gases are being measured from airborne platforms, flying low and slow in the boundary later.  Airborne concentrations, made at low altitude in the boundary layer, integrate over microtopographic features but allow distinguishing different fluxes between landscapes.  From spatial and diurnal gradients in concentrations, we can infer surface fluxes, linked to different landscapes.  These techniques, combined with plot and ecosystem scale measurements and experimentation allow diagnosing climate sensitivity of the carbon cycle across scales.