P. Camill et al., Changes in biomass, aboveground net primary production, and peat accumulation following permafrost thaw in the boreal peatlands of Manitoba, Canada, ECOSYSTEMS, 4(5), 2001, pp. 461-478
Permafrost thaw resulting from climate warming may dramatically change the
succession and carbon dynamics of northern ecosystems. To examine the joint
effects of regional temperature and local species changes on peat accumula
tion following thaw, we studied peat accumulation across a regional gradien
t of mean annual temperature (MAT). We measured aboveground net primary pro
duction (AGNPP) and decomposition over 2 years for major functional groups
and used these data to calculate a simple index of net annual aboveground p
eat accumulation. In addition, we collected cores from six adjacent frozen
and thawed bog sites to document peat accumulation changes following thaw o
ver the past 200 years. Aboveground biomass and decomposition were more str
ongly controlled by local succession than regional climate. AGNPP for some
species differed between collapse scars and associated permafrost plateaus
and was influenced by regional MAT. A few species, such as Picea mariana tr
ees on frozen bogs and Sphagnum mosses in thawed bogs, sequestered a dispro
portionate amount of peat; in addition, changes in their abundance followin
g thaw changed peat accumulation. Pb-210-dated cores indicated that peat ac
cumulation doubles following thaw and that the accumulation rate is affecte
d by historical changes in species during succession. Peat accumulation in
boreal peatlands following thaw was controlled by a complex mix of local ve
getation changes, regional climate, and history. These results suggest that
northern ecosystems may show responses more complex than large releases of
carbon during transient warming.