As part of the Canadian Carbon Program (CCP), Environment Canada agreed to support a collaborative effort to install and run high-precision carbon dioxide , methane and carbon monoxide measurements at a western peatland flux measurement site located near Lac La Biche, Alberta. Dr. Larry Flanagan at the University of Lethbridge is the main PI for this flux measurement site.
Background Information for the Western Peatland (Lac Labiche) Flux Station:
Canada has between 40-50% of the world's peatlands (defined as minimum organic soil depth of 40 cm) and they cover 10-12% of Canada's land surface. Their importance in the climate system is that they (a) have immense stores of C (250 to 450 Gt C), (b) have slow, persistent uptake of CO2 (20 to 30 g C m-2 yr-1), and (c) are a large source of atmospheric methane (0 200 mg m-2 yr-1) . Land use changes are altering both the store of C and the exchange of methane. For example, peat extraction, a multi-million dollar industry with activities in NB, QC, and AB, reduces the amount of stored C by removing some 0.5 to 0.7 million tons C yr-1. Wetland creation has become an important activity, particularly where wetlands have been affected by agriculture and urbanization. It is common that high-quality agricultural C sinks are replaced by shallow, flooded wetlands with emergent vegetation that are usually high methane emitters. However, the effects of both peat extraction and wetland creation on the C cycle are very small compared to that possible due to climate change. Wetlands are more tightly coupled to climate and the hydrological cycle than most other ecosystems. Small changes in moisture storage can dramatically alter the C cycling within peat accumulating wetlands. For example, lowering the water table depth from 0.1 to 0.2 m below the peat surface can change a peatland from a sink to a large source of CO2 and from a large source to a sink of CH4. Since the decomposition of the large residual pool of C is so important to the C balance of wetlands, temperature also plays a critical role. One of the next major additions to global coupled climate models is the incorporation of wetlands to examine the CO2 - CH4 feedback .
Canada's peatlands represent the largest pool of C in the Canadian terrestrial biosphere. Recent studies suggest that some peatlands types in eastern Canada may have a contemporary sink 3 to 4 times larger than what has been inferred from past records. The past estimates were obtained from peat cores, while the contemporary estimate of between 60 and 70 g C m-2 yr-1 was obtained by EC measurements. The reason for the larger contemporary sink is still unknown, but is likely due to a combination of climate change, CO2 fertilization, and/or nitrogen deposition. There are only two other sites, both in northern Finland and Sweden, where continuous, multi-year records of CO2 exchange have been obtained. These results indicate that these sites are also C sinks, but with much higher inter-annual variability than has been observed in eastern Canada. In addition, no other project, as far as we know, is attempting to link contemporary and past accumulation rates as has been done in eastern Canada. Understanding the present peatland sink and its future fate requires that continuous measurements be obtained from (a) similar peatland types in different ecoclimatic regions, i.e., controlling for ecosystem structure but varying climate drivers, and (b) from different peatland types in the same ecoclimatic region, i.e., controlling for regional climate but varying ecosystem structure and possibly function. There is considerable debate over the utility of peatlands as net sinks of GHGs, but it is clear that there is insufficient data to conclude whether or not these ecosystems should be included in GHG management strategies. Roulet (2000) suggests that preservation, restoration, and creation of peatlands can significantly affect C accounting. However, the most compelling reason for developing a more complete understanding of peatland C dynamics is the recognition that the oxidation of just 1% in the organic C stored in Canadian peatlands is equivalent to five to ten years of Canada's anthropogenic emissions of CO2.
Peatlands in Canada present an ideal setting for testing some of these ideas. The same types of peatlands exist in eastern and western Canada, even though the moisture regimes are considerably different. In eastern Canada, there is generally a 200 to 400 mm excess of precipitation over potential evapotranspiration, while in western Canada there is little excess water, i.e., P @ Et. One bog, Mer Bleue in eastern Ontario and a moderately rich, treed fen near LaBiche River in northern Alberta, have been selected for permanent sites to examine how differences in climate affect peatland NEP. The theoretical model of Hilbert et al. (2000) suggests that fens are more sensitive than bogs to variations in climate and hydrology. A third permanent peatland site, the BOREAS SSA fen, will be operated by NWRI during the growing season. At both the Alberta and eastern locations, other peatland types will be examined over shorter periods of time to compare how the structure and function of different peatlands affects NEP and the components (ER, GPP) that make up NEP.