Variations in nitrogen, phosphorus, and δ 15 N in Sphagnum mosses along a climatic and atmospheric deposition gradient in eastern Canada

作者：Tatjana Živković, Kristina Disney, Tim R. Moore · 发表于：Botany · 年份：2017 · DOI：10.1139/cjb-2016-0314 · 被引用次数：18 · 研究领域：Peatlands and Wetlands Ecology、Coastal wetland ecosystem dynamics、Botany and Plant Ecology Studies

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 eight bogs along a transect from ∼45 to ∼55°N in Ontario and 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 the water table. We interpret this to indicate a greater dependence on N 2 -fixation for N acquisition in the northern and wetter sites.