Peatland Vascular Plant Leaf N Concentrations (5 species) From Leaves collected from N-Addition plots in an Alberta Poor Fen, 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. To examine responses to N
deposition, over five years, we experimentally applied N (as NH4NO3)
to a poor fen near Mariana Lake, Alberta, at rates of 0, 5, 10, 15,
20, and 25 kg N ha-1 yr-1, plus controls (no water or N addition). In
July of each year, we collected new growth of 5 species of vascular
plants, returned them to the lab, cleaned them, dried and ground them,
and ran them on a Flash EA 1112 Series CN Soil Analyzer Leaf N
concentrations in C. calyculata, A. polifolia, and V. oxycoccos
increased significantly with increasing N addition (Fig. 5). For C.
calyculata and A. polifolia, there were differences in N
concentrations between years, but the regression slopes describing the
response to N addition were consistent across all years. Leaf N
concentrations were unaffected by N addition for E. vaginatum and S.
palustris, with the latter exhibiting interannual differences in leaf
N concentrations. Water addition alone had no significant effect on N
concentrations for any of the vascular plant species (p >= 0.67).