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标题：Contrasting Responses of Nitrogen-Fixation in Arctic Lichens to Experimental and Ambient Nitrogen and Phosphorus Availability
其他标题：Contrasting Responses of Nitrogen-Fixation in Arctic Lichens to Experimental and Ambient Nitrogen and Phosphorus Availability
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作者：Marissa Weiss ; Sarah E. Hobbie ; Gretchen M. Gettel 等
期刊名称：Arctic, Antarctic, and Alpine Research
印刷版ISSN：1523-0430
电子版ISSN：1938-4246
出版年度：2005
卷号：37
期号：3
页码：396-401
DOI：10.1657/1523-0430(2005)037[0396:CRONIA]2.0.CO%3B2
摘要：We investigated the influence of nitrogen (N) and phosphorus (P) on N 2 -fixation and abundance of two of the most common N 2 -fixing arctic lichens, Peltigera aphthosa and P. polydactyla , in two common moist upland tundra types, acidic and non-acidic tundra, at Toolik Lake, Alaska. Acidic tundra has higher N and lower P availability than non-acidic tundra. We measured the abundance of the lichens in control (no fertilization), N- and P-fertilized plots, and N 2 -fixation using the acetylene reduction assay method on lichens from control and P-fertilized plots from both tundra types. Lichens on N-treated plots were too scarce to include in our N 2 -fixation estimates. Lichen abundance was lower in plots fertilized with N than in control and P-fertilized plots, while per-biomass N 2 -fixation rates were higher in P-fertilized plots than in control plots. Per-biomass rates of N 2 -fixation did not differ between acidic and non-acidic tundra, but both lichen species are more abundant on acidic tundra. Thus, despite per-biomass stimulation of N 2 -fixation by experimental P addition and reduction in lichen abundance with N fertilization, Peltigera contributes more N to the acidic tundra site, indicating that soil N and P availability are not the primary controls of N 2 -fixation and abundance of these lichens.