Interacting Controls on Ecosystem Photosynthesis and Respiration in Contrasting Peatland Ecosystems

Abstract

Photosynthesis in moss contributes significantly to carbon gain in northern peatland ecosystems. In turn, these northern peatland ecosystems contain a large fraction of the global soil carbon stock, which has been suggested to be vulnerable to warming and drying associated with climate change. The fate of this vast peatland carbon stock depends on the relative responses of ecosystem photosynthesis and respiration to climate change-induced shifts in environmental conditions. This chapter reviews some recent studies of the controls on ecosystem photosynthesis and respiration in contrasting peatland ecosystems in northern Alberta, Canada, a region where peatlands occupy a significant fraction of the landscape. In particular, it is highlighted how (i) differences in dominant plant functional type, (ii) interactions between variation in water table depth and temperature, and (iii) ecosystem succession, can all strongly control the rate of net carbon sequestration in peatland ecosystems and influence the response of these ecosystems to variation in environmental conditions associated with anticipated climate change. Prediction of future climate change effects on peatland ecosystems would be improved if global-scale models could include more details of the biological variability among peatlands (both spatial and temporal), with realistic parameterizations of the responses of photosynthesis and respiration to variation in temperature, water table depth and soil moisture.