title: Diversification of Nitrogen Sources in Various Tundra Vegetation Types in the High Arctic.
abstract: Low nitrogen availability in the high Arctic represents a major constraint for plant growth, which limits the tundra capacity for carbon retention and determines tundra vegetation types. The limited terrestrial nitrogen (N) pool in the tundra is augmented significantly by nesting seabirds, such as the planktivorous Little Auk (Alle alle). Therefore, N delivered by these birds may significantly influence the N cycling in the tundra locally and the carbon budget more globally. Moreover, should these birds experience substantial negative environmental pressure associated with climate change, this will adversely influence the tundra N-budget. Hence, assessment of bird-originated N-input to the tundra is important for understanding biological cycles in polar regions. This study analyzed the stable nitrogen composition of the three main N-sources in the High Arctic and in numerous plants that access different N-pools in ten tundra vegetation types in an experimental catchment in Hornsund (Svalbard). The percentage of the total tundra N-pool provided by birds, ranged from 0-21% in Patterned-ground tundra to 100% in Ornithocoprophilous tundra. The total N-pool utilized by tundra plants in the studied catchment was built in 36% by birds, 38% by atmospheric deposition, and 26% by atmospheric N2-fixation. The stable nitrogen isotope mixing mass balance, in contrast to direct methods that measure actual deposition, indicates the ratio between the actual N-loads acquired by plants from different N-sources. Our results enhance our understanding of the importance of different N-sources in the Arctic tundra and the used methodological approach can be applied elsewhere.
authors.affiliation: West Australian Biogeochemistry Centre, School of Plant Biology, The University of Western Australia, Crawley, Western Australia, Australia.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Skrzypek
authors.affiliation: Department of Ecology, Biogeochemistry and Environmental Protection, The University of Wrocław, Wrocław, Poland.
authors.forename: Bronisław
authors.initials: B
authors.lastname: Wojtuń
authors.affiliation: Department of Botany and Plant Ecology, The Wrocław University of Environmental and Life Sciences, Wrocław, Poland.
authors.forename: Dorota
authors.initials: D
authors.lastname: Richter
authors.affiliation: Department of Vertebrate Ecology and Zoology, The University of Gdańsk, Gdańsk, Poland.
authors.forename: Dariusz
authors.initials: D
authors.lastname: Jakubas
authors.affiliation: Department of Vertebrate Ecology and Zoology, The University of Gdańsk, Gdańsk, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Wojczulanis-Jakubas
authors.affiliation: Department of Ecology, Biogeochemistry and Environmental Protection, The University of Wrocław, Wrocław, Poland.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Samecka-Cymerman
mesh_terms: D000818:Animals; D001110:Arctic Regions; D001272:Atmosphere / Q000737:chemistry; D001717:Birds; D005243:Feces / Q000737:chemistry; D009584:Nitrogen / Q000032:analysis*; D009586:Nitrogen Fixation; D010944:Plants / Q000737:chemistry*; D062206:Spatial Analysis; D065929:Tundra
chemical_list: D009584:Nitrogen