Comparison of decomposition of belowground and aboveground plant litters in peatlands of boreal Alberta, Canada

Studies examining the decomposition rates of belowground plant tissues in p eatlands are scarce despite the significant contribution these tissues make to total plant production. Therefore, we measured mass losses of Carex aqu atilis Wahlenb. leaves and rhizomes and Salix planifolia Pursh leaves and r oots in a rich, sedge-dominated fen and Sphagnum fuscum (Schimp.) Klinggr. plants in a forested bog using the litter bag technique over a 2-year perio d in southern boreal Alberta. After 2 years, mass losses of C. aquatilis rh izomes (75%) were significantly higher than those of C. aquatilis leaves an d Salix planifolia leaves, which were similar to each other (54 and 48%, re spectively). Sphagnum fuscum and Salix planifolia root mass losses also wer e similar to each other (21 and 29%, respectively), but they were significa ntly lower than those of the other three litter types. Different tissue nut rient concentrations as well as alkalinity- and phosphorus-related surface water chemistry variables correlated significantly with mass losses of diff erent litter types; however, they alone did not explain all of the mass los s trends. The majority of sedge peat and carbon in the fen originates from C. aquatilis leaves (188 and 86 g.m(-2), respectively), with the remainder originating from C. aquatilis rhizomes (102 and 47 g.m(-2), respectively) a fter the first 2 years of decomposition. Conversely, the majority of Salix planifolia peat and carbon originates from its roots (33 and 16 g.m(-2), re spectively) and the remainder from its leaves (24 and 11 g.m(-2), respectiv ely) over the same period. After the first 2 years of decomposition, 150 g. m(-2) of peat and 71 g.m(-2) of carbon remained from the decomposing Sphagn um fuscum in the bog.