Early goose arrival increases soil nitrogen availability more than an advancing spring in coastal western Alaska

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An understudied aspect of climate change-induced phenological mismatch is its effect on ecosystem functioning, such as nitrogen (N) cycling. The timing of migratory herbivore arrival may alter N inputs and plant-herbivore feedbacks, while earlier springs are predicted to increase N cycling rates. However, the relative importance of these shifts in timing and how they interact to affect N cycling are largely unknown. We conducted a three-year factorial experiment in coastal western Alaska that simulated different timing of Pacific black brant (Branta bernicla nigricans) arrival (3-weeks early, typical, 3-weeks late, or no-grazing) and different starting times of the growing season (ca. 3-weeks advanced and ambient) on soil-adsorbed inorganic (NH4+-N, NO3--N), and mobile pore water pools organic (amino acids). Early grazing increased mobile NH4+-N, NO3--N, and amino acids by 103%, 119%, and 7%, respectively, while late grazing reduced soil-adsorbed NH4+-N and NO3--N by 16% and 17%, respectively. In comparison, the advanced growing season increased inorganic mobile NH4+-N by 26%. The arrival time by geese and the start of the season did not interact to influence soil N availability. While the onset of spring in our system is occurring earlier at twice the rate of migratory goose arrival, earlier goose migration is likely to be more significant than the advances in springs in influencing soil N, although both early goose arrival and advanced springs are likely to increase N availability in the future. This increase in soil N resources can have a lasting impact on plant community composition and productivity in this N-limited ecosystem.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Early goose arrival increases soil nitrogen availability more than an advancing spring in coastal western Alaska
Series title Ecosystems
DOI 10.1007/s10021-019-00472-9
Edition Online First
Year Published 2020
Language English
Publisher Springer
Contributing office(s) Alaska Science Center Biology WTEB
Country United States
Other Geospatial Coastal western Alaska
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