Nitrogen dynamics in arctic tundra soils of varying age: differential responses to fertilization and warming

TitleNitrogen dynamics in arctic tundra soils of varying age: differential responses to fertilization and warming
Publication TypeJournal Article
Year of Publication2013
AuthorsYano Y., Shaver GR, Rastetter E.B, Giblin A.E, Laundre J.A
JournalOecologiaOecologiaOecologia
Volume173
Pagination1575-1586
Date PublishedDec
ISBN Number0029-8549
Accession NumberISI:000328210000038
Keywordsamino 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 TitleOecologiaOecologia
Alternate JournalOecologia