Variations in nitrogen, phosphorus, and δ¹⁵N in Sphagnum mosses along a climatic and atmospheric deposition gradient in eastern Canada

Abstract

We examined concentrations of nitrogen (N) and phosphorus (P) and δ 15 N value in Sphagnum sections Acutifolia and Cuspidata inhabiting hummocks and hollows from 8 bogs along a transect from ~45 to ~55 °N in Ontario/Quebec. The N concentration in Sphagnum declined from South to North, correlating with a decrease in atmospheric N deposition. Although the overall N concentration was larger in hollows than hummocks, the pattern was inconsistent across the sites.There was a proportionally larger decline in P concentration from South to North and an overall larger P concentration in hollows than hummocks, but there were inconsistent differences across the sites. The N:P ratio ranged from 12:1 to 29:1, driven primarily by the variation in P concentration. Ratios of N and P concentration in Sphagnum capitulum:stem averaged 1.2:1, suggesting nutrient resorption from stem to capitulum during growth; the ratio rose with increasing N and P concentration in the capitulum. The δ 15 N value of Sphagnum rose from ~-6‰in the South to ~-1‰ in the North, correlated with the decrease in Sphagnum N concentration and with a rise in water table. We interpret this to indicate a greater dependence on N 2 -fixation for N acquisition in the northern and wetter sites.

Changes in Canada's Phosphorus Cycle 1961–2018: Surpluses and Deficits

“…We assumed no inter‐provincial trade in fertilizers since this information is not available. Atmospheric deposition, typically neglected or regarded as a constant in previous studies (Chen & Graedel, 2016; Wironen et al., 2018), was assumed to be 0.4 kg P ha −1 y −1 , which is consistent with field observations (Živković et al., 2017). Irrigation water P was estimated by multiplying monitored P concentration of source water (0.05 mg L −1 ) (Little et al., 2010) by irrigation volume reported in Statistics Canada.…”

Anthropogenic global shifts in biospheric N and P concentrations and ratios and their impacts on biodiversity, ecosystem productivity, food security, and human health

“…Many recent studies have reported increases in the N:P ratio in the soil, water, and plants of terrestrial and aquatic ecosystems (Blanes, Viñegla, Merino, & Carreira, ; Crowley et al, ; Hessen, ; Huang, Liu, et al, ; Jirousek, Hajek, & Bragazza, ; Lepori & Keck, ; Xu, Pu, Li, & Zhu, ; Yu et al, ; Zivkovic, Disney, & Moore, ) in response to “high levels of atmospheric N deposition” (Table ).…”

Defining the Sphagnum Core Microbiome across the North American Continent Reveals a Central Role for Diazotrophic Methanotrophs in the Nitrogen and Carbon Cycles of Boreal Peatland Ecosystems

“…Biogeochemical evidence points to an important role for Sphagnum -associated prokaryotic populations in mediating critical ecosystem processes such as methane oxidation (methanotrophy) and nitrogen fixation (diazotrophy) ( 34 – 36 , 48 , 51 – 54 ). For example, Sphagnum -associated methanotrophs act as a natural methane biofilter and provide up to one-third of Sphagnum carbon needs ( 29 , 31 , 32 , 34 ).…”