Title | Nitrogen dynamics in arctic tundra soils of varying age: differential responses to fertilization and warming |
Publication Type | Journal Article |
Year of Publication | 2013 |
Authors | Yano Y., Shaver GR, Rastetter E.B, Giblin A.E, Laundre J.A |
Journal | OecologiaOecologiaOecologia |
Volume | 173 |
Pagination | 1575-1586 |
Date Published | Dec |
ISBN Number | 0029-8549 |
Accession Number | ISI:000328210000038 |
Keywords | amino acids, amino-acids, available nitrogen, carbon storage, different glacial histories, hydrolyzable nitrogen, litter decomposition, nonacidic tundra, northern alaska, organic nitrogen, plant community composition, protein, proteins, species richness, terrestrial ecosystems |
Abstract | In the foothills of the Brooks Range, Alaska, different glaciation histories have created landscapes with varying soil age. Productivity of most of these landscapes is generally N limited, but varies widely, as do plant species composition and soil properties (e.g., pH). We hypothesized that the projected changes in productivity and vegetation composition under a warmer climate might be mediated through differential changes in N availability across soil age. We compared readily available [water-soluble NH4 (+), NO3 (-), and amino acids (AA)], moderately available (soluble proteins), hydrolyzable, and total N pools across three tussock-tundra landscapes with soil ages ranging from 11.5k to 300k years. The effects of fertilization and warming on these N pools were also compared for the two younger sites. Readily available N was highest at the oldest site, and AA accounted for 80-89 % of this N. At the youngest site, inorganic N constituted the majority (80-97 %) of total readily available N. This variation reflected the large differences in plant functional group composition and soil chemical properties. Long-term (8-16 years) fertilization increased the soluble inorganic N by 20- to 100-fold at the intermediate-age site, but only by twofold to threefold at the youngest site. Warming caused small and inconsistent changes in the soil C:N ratio and AA, but only in soils beneath Eriophorum vaginatum, the dominant tussock-forming sedge. These differential responses suggest that the ecological consequences of warmer climates on these tundra ecosystems are more complex than simply elevated N-mineralization rates, and that the responses of landscapes might be impacted by soil age, or time since deglaciation. |
Short Title | OecologiaOecologia |
Alternate Journal | Oecologia |