Aboveground peat and carbon accumulation potentials along a bog-fen-marsh wetland gradient in southern boreal Alberta, Canada

Production-to-decomposition quotients and asymptotic limits of peat accumul ation were determined to estimate peat and carbon accumulation potentials a long a bog-fen-marsh wetland gradient in southern boreal Alberta. The wetla nds were a bog, a poor fen (PF), a. wooded moderate-rich fen (WRF), a lacus trine sedge fen (LSF), a riverine sedge fen (RSF), a riverine marsh (RM), a nd a lacustrine marsh (LM). First year mass losses increased along this gra dient (bog 14%, fens 25-61%, marshes 57-62%), with second year total mass l osses increasing from 18 to 38% from the bog to the moderate-rich fens. Rat ios of aboveground net primary production to decomposition and asymptotic l imits of peat accumulation showed decreasing trends from the bog to the fen s to the marshes as decay rates increased along the same gradient. The Spha gnum-dominated sites (bog, PF) showed greater pea accumulation potentials t han the brown moss-dominated sites (WRF, LSF) and those sites with an insig nificant-to-no moss stratum (RSF, RM, LM), which is paralleled by their dec reasing peat thicknesses. Rates of litter accumulation in the first year av eraged 170 g m(-2) yr(-1) in Sphagnum-dominated sites, 130 g m(-2) yr(-1) i n brown moss-dominated sites, and 103 g m(-2) yr(-1) in sites with an insig nificant-to-no moss stratum. All three wetland types showed similar carbon accumulation potentials (83, 67, and 50 g m(-2) yr(-1), respectively) after the first year of decomposition. Peat depth, asymptotic limits of peat acc umulation, and production-to-decomposition ratios correlated negatively wit h water levels, pH, and Ca2+, and they correlated positively with moss and woody plant production (shrubs, trees). Peatlands with strong moss and shru b/tree strata (bog, PF, WRF) accumulate more peat than those wetlands domin ated by graminoids (LSF, RSF RM, LM). In the bog, high peat accumulation po tentials may be related to low rates of decomposition. The peat accumulatio n potentials of some fens (PF, WRF) are similar to the bog and may be maint ained by higher decomposition rates, which are offset by higher litter inpu ts. In the graminoid-dominated fens and marshes, peat accumulation potentia ls are lowest and may be related to higher litter quality, resulting in hig her decomposition rates.