Additional nitrogen in arctic‐alpine soils and plants—a pilot study with 15 NO$ _3^ - $ and 15 NH$ _4^+ $ fertilization along an elevation gradient

• Published in: Journal of Plant Nutrition and Soil Science
• Main Authors: Ackermann, Simone, Amelung, Wulf, Löffler, Jörg
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2015
• Subjects: Arctic
• Online Access: http://dx.doi.org/10.1002/jpln.201500008; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjpln.201500008; https://onlinelibrary.wiley.com/doi/pdf/10.1002/jpln.201500008; https://onlinelibrary.wiley.com/doi/full-xml/10.1002/jpln.201500008

Abstract Nitrogen (N) deposition has been increasing in alpine ecosystems, but its fate in soils and plants remains unclear. We assumed that the increased N load will be efficiently retained in alpine ecosystems but that the degree of N use efficiency changes with elevation. Thus, we performed a 3‐year 15 N tracer experiment, in which we added 1 g m −2 of either NH 4 15 NO 3 or 15 NH 4 NO 3 fertilizer to a plot of 1 m 2 in size at three elevations. Composite soil samples and aboveground plant material from lichens, dwarf shrubs, and graminoids were collected annually for three years and analyzed for their 15 N accrual. We found a cumulative and plateauing rise in 15 N concentration in soils and plants at all sites. However, overall recovery of the tracer decreased with time, amounting to 71% of fertilizer recovered in the soils in the first year, 69% recovered in soils and plants in the second year, and 37% in soils and plants in the third year. Moreover, the fertilizer use efficiency varied among fertilizer types and plant functional types. This utilization pattern appears to be modulated by elevation.