Long-term deeper snow causes changes in litter quality, soil C and N storage in moist acidic tundra in Northern Alaska
Abstract
Tundra ecosystems store over one third of the global terrestrial organic C pool and have the potential to release large amounts of CO2 as organic matter decomposition is expected to increase as climate warms and precipitation changes. However, a warming climate and increased snow pack soil thermal insulation is expected to shift dominant vegetative cover type affecting above and below ground litter quality, soil organic matter storage depth, and decomposition rates in respective soils. These changes can affect the magnitude and even direction of soil C storage in the Arctic tundra.. At a sixteen-year snow fence experiment at Toolik Lake, as part of the International Tundra Experiment (ITEX), increased snow pack resulted in a shift from a Sphagnum moss-dominated mixed graminoid-deciduous ecosystem (moist tussock tundra) to one covered largely by deciduous shrubs and Carex in more water-saturated soil conditions. We investigated relationships between shifting dominance of plant species and impacts to soils using a multiproxy isotope and biomarker approach in plants and soils from the areas with control, deep, intermediate, and low snow pack. A comparison of the same plant species (Betula nana, Carex bigelowii, Eriophorum vaginatum, Salix pulchra, and Sphagnum spp.) along the snow zones showed leaf tissue C-to-N ratio decreasing in the deep snow areas when compared to control and low snow pack areas, driven by an increase in plant N content. Root and stem tissue was impacted similarly across the experimental treatments. Changes in soil δ13C and δ15N values with depth and along the transect demonstrate impacts to C and N cycling. These results demonstrate litter quality and soil carbon storage feedbacks in response to snow pack thermal insulation that could influence litter accumulation, decay rates and the chemical nature of soil carbon under climate conditions with deeper snow in winter.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMGC53B1059M
- Keywords:
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- 0315 ATMOSPHERIC COMPOSITION AND STRUCTURE Biosphere/atmosphere interactions;
- 0454 BIOGEOSCIENCES Isotopic composition and chemistry;
- 0793 CRYOSPHERE Biogeochemistry;
- 1631 GLOBAL CHANGE Land/atmosphere interactions