Fresh air for the mire-breathing hypothesis: Sphagnum influence on CO2 exchange in a northern peatland

One mechanism for Sphagnum mosses to tolerate lowered peatland water tables is ‘mire-breathing’, wherein the surface elevation increases or decreases to track rising and lowering water tables (WT). The relevance of mire-breathing to more rigid hummock growth forms remains unclear. In this study we use a combination of hyperspectral analysis, CO2 flux measurements, and analysis of moss growth and physical characteristics to evaluate mire-breathing as a mechanism of drought tolerance in Sphagnum-mesocosms. Results suggest that hummock expansion and contraction during wetting and drying is a more effective mire-breathing mechanism than the rising and falling of the hollow surface.