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- Title
Nitrogen dynamics in arctic tundra soils of varying age: differential responses to fertilization and warming.
- Authors
Yano, Yuriko; Shaver, Gaius R.; Rastetter, Edward B.; Giblin, Anne E.; Laundre, James A.
- 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 NH 4+, NO 3−, 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.
- Subjects
BROOKS Range (Alaska); NITROGEN in soils; AGE of soils; FERTILIZATION (Biology); CHEMICAL composition of plants; AMINO acids
- Publication
Oecologia, 2013, Vol 173, Issue 4, p1575
- ISSN
0029-8549
- Publication type
Article
- DOI
10.1007/s00442-013-2733-5