Tundra wildfire triggers sustained lateral nutrient loss in Alaskan Arctic
| Autor: | Randy Fulweber, Gregory T. Carling, Adrian V. Rocha, S. Ludwig, Rebecca J. Frei, Amanda Huebner, Arial J. Shogren, Frances Iannucci, Jay P. Zarnetske, Benjamin W. Abbott, Leika Patch, Jonathan A. O'Donnell, Rachel Watts, William B. Bowden, Samuel P. Bratsman |
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| Rok vydání: | 2020 |
| Předmět: |
0106 biological sciences
010504 meteorology & atmospheric sciences Growing season Permafrost 010603 evolutionary biology 01 natural sciences Wildfires Soil Nutrient Environmental Chemistry Ecosystem Organic matter Tundra 0105 earth and related environmental sciences General Environmental Science Total organic carbon chemistry.chemical_classification Global and Planetary Change Ecology Arctic Regions Aquatic ecosystem Nutrients 15. Life on land chemistry 13. Climate action Environmental chemistry Environmental science Alaska |
| Zdroj: | Global change biologyREFERENCES. 27(7) |
| ISSN: | 1365-2486 |
| Popis: | Climate change is creating widespread ecosystem disturbance across the permafrost zone, including a rapid increase in the extent and severity of tundra wildfire. The expansion of this previously rare disturbance has unknown consequences for lateral nutrient flux from terrestrial to aquatic environments. Lateral loss of nutrients could reduce carbon uptake and slow recovery of already nutrient-limited tundra ecosystems. To investigate the effects of tundra wildfire on lateral nutrient export, we analyzed water chemistry in and around the 10-year-old Anaktuvuk River fire scar in northern Alaska. We collected water samples from 21 burned and 21 unburned watersheds during snowmelt, at peak growing season, and after plant senescence in 2017 and 2018. After a decade of ecosystem recovery, aboveground biomass had recovered in burned watersheds, but overall carbon and nitrogen remained ~20% lower, and the active layer remained ~10% deeper. Despite lower organic matter stocks, dissolved organic nutrients were substantially elevated in burned watersheds, with higher flow-weighted concentrations of organic carbon (25% higher), organic nitrogen (59% higher), organic phosphorus (65% higher), and organic sulfur (47% higher). Geochemical proxies indicated greater interaction with mineral soils in watersheds with surface subsidence, but optical analysis and isotopes suggested that recent plant growth, not mineral soil, was the main source of organic nutrients in burned watersheds. Burned and unburned watersheds had similar δ15 N-NO3 - , indicating that exported nitrogen was of preburn origin (i.e., not recently fixed). Lateral nitrogen flux from burned watersheds was 2- to 10-fold higher than rates of background nitrogen fixation and atmospheric deposition estimated in this area. These findings indicate that wildfire in Arctic tundra can destabilize nitrogen, phosphorus, and sulfur previously stored in permafrost via plant uptake and leaching. This plant-mediated nutrient loss could exacerbate terrestrial nutrient limitation after disturbance or serve as an important nutrient release mechanism during succession. |
| Databáze: | OpenAIRE |
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