Sphagnum fuscum Growth and N Concentration in an Alberta Peatland Subjected to Increasing Nitrogen Deposition, 2011-2015

Development of the oil sands has led to increasing atmospheric N
deposition, with values as high as 17 kg N
ha -1 yr -1 ;
regional background levels <2 kg N ha -1 yr -1 . Bogs, being ombrotrophic, may be
especially susceptible to increasing N deposition. To examine
responses to N deposition, over five years, we experimentally applied
N (as NH 4 NO 3 ) to a bog
near Mariana Lakes, Alberta, at rates of 0, 5, 10, 15, 20, and 25 kg N
ha -1 yr -1 , plus
controls (no water or N addition). Data collected of the growing
season using the crank wire method allowed for the calculation of NPP.
Tissues were also collected and analyzed on Leco TruSpec CN analyzer.
Increasing N addition had no effect on Sphagnum
fuscum NPP in year 1, but inhibited S.
fuscum NPP in years 2-5, with capitula N concentrations
remaining consistent across all years, but with stem N concentrations
increasing with N input. The decrease in S.
fuscum NPP with increasing N addition that we report for
Mariana Lakes Bog has implications for peat accumulation in bogs.