Variation in bird’s originating nitrogen availability limits High Arctic tundra development over last 2000 year (Hornsund, Svalbard)

• Main Authors: Skrzypek, G, Wojtún, B, Hua, Q, Richter, D, Jakubas, D, Wojczulanis–Jakubas, K, Samecka–Cymerman, A
• Format: Conference Object
• Language: English
• Published: European Geosciences Union 2020
• Subjects: Arctic; Birds; Nitrogen; Arctic regions; Carbon; Tundra; Climate change; Hornsund; Svalbard; Alle alle; Arctic birds; Subarctic
• Online Access: http://apo.ansto.gov.au/dspace/handle/10238/9211; https://meetingorganizer.copernicus.org/EGU2016/EGU2016-10665.pdf

Arctic and subarctic regions play important roles in the global carbon balance. However, nitrogen (N) defi-ciency is a major constraint for organic carbon sequestration in the High Arctic. Hence, the identification of therelative contributions from different N-sources is critical for understanding the constraints that limit tundra growth.The stable nitrogen composition of the three main N-sources and numerous plants were analyzed in tentundra types (including those influenced by seabirds) in the Fuglebekken catchment (Hornsund, Svalbard, 77◦N15◦E). The percentage of the total tundra N-pool provided by seabirds’ feces (from planktivorous coloniallybreeding little auks Alle alle), ranged from 0–21% in Patterned-ground tundra to 100% in Ornithocoprophiloustundra. The total N-pool utilized by tundra plants in the studied catchment originated from birds (36%),atmospheric deposition (38%), and N2-fixation (26%). The results clearly show that N-pool in the tundra issignificantly supplemented by nesting seabirds. Thus, if they experienced climate change induced substantialnegative environmental pressure, it would adversely influence the tundra N-budget (Skrzypek et al. 2015).The growth rates and the sediment thickness (<15cm) in different tundra types varied considerably but thetundra age was similar in the whole area, <450 cal BP. The only exception was Ornithocoprophilous bird-N richtundra with very diverse ages ranging from 235 to 2300 cal BP and thickness up to 110 cm. The growth rates forthis tundra (62 cm core, 18 AMS 14C dates) were high (1.5-3.0 mm/yr) between 1568 and 1804 AD and thensubstantially declined for the period between 1804 and 1929 AD (0.2 mm/yr). These findings deliver an additionalargument, that the organic matter accumulation is driven not only directly by climatic conditions but also by birds’contribution to the tundra N-pool. © 2016 Author(s)