Background for the CENPERM research program (2)
Complicated feedback mechanisms
Arctic ecosystem feedback mechanisms and processes interact on micro, local and regional scales. This is further complicated by several potential feedback mechanisms likely to occur in permafrost-affected ecosystems, involving the interactions of microorganisms, vegetation and soil:
- heat production linked to microbial activity and resulting in accelerated warming
- microbial priming effects that lead to mobilization of "old", recalcitrant organic matter. This happens through microorganisms activated by labile carbon input from "young" biomass - for example from increased plant growth as a consequence of climate warming. The result is a subsequent net carbon loss
- positive feedbacks linked to the nitrogen cycle, including increased mineralization rates, nitrogen release from thawing permafrost, and increased plant growth as a consequence of enhanced nitrogen availability for plants.
Neither of the above-mentioned processes have yet been integrated in a landscape approach, nor have they been quantified simultaneously by assessing the complex interactions between permafrost dynamics, microbial activity and plant growth. Processes are so poorly understood that incorporation into global climate models has not been attempted for long term predictions.
The CENPERM rationale
This requires large-scale field manipulation experiments coupled to studies of activity of microorganisms and responses of plants and the integration of carbon cycling with other elements, particularly nitrogen. Furthermore, new insights in permafrost processes need to be scaled up to assess the regional importance of future changes.
Processes in the uppermost active soil layers have more or less been successfully scaled up based on different vegetation and soil indices. New tools are needed as permafrost characteristics cannot be scaled similarly.
In conclusion, it remains one of the most formidable challenges facing leading scientists already working in Greenland to put all efforts into one ambition: CENPERM.