HR: 1340h
AN: B23A-0944 [Abstracts]
TI: Soil Carbon Stabilization Along Climate and Stand Productivity Gradients in Black Spruce Forests of
Interior Alaska
AU: * Kane, E S
EM: ftesk@uaf.edu
AF: University of Alaska, Fairbanks, Forest Sciences Dept.
304 O'Neill Bldg., Fairbanks, AK 99709
United States
AU: Valentine, D W
EM: ffdwv@uaf.edu
AF: University of Alaska, Fairbanks, Forest Sciences Dept.
304 O'Neill Bldg., Fairbanks, AK 99709
United States
AU: Schuur, E A
EM: tschuur@ufl.edu
AF: University of Florida, Gainesville, 220 Bartram Hall, Gainesville, FL 32611
United States
AU: Dutta, K
EM: kdutta@ufl.edu
AF: University of Florida, Gainesville, 220 Bartram Hall, Gainesville, FL 32611
United States
AB:
The amount of soil organic carbon (SOC) in stable, slow turnover pools is likely to change in response to climate warming
because processes mediating soil C balance (net primary production and decomposition) vary with environmental conditions.
This is important to consider in boreal forests, which comprise one of the world's largest stocks of SOC. We investigated
changes in soil C stabilization along four replicate gradients of black spruce productivity and soil temperature in interior
Alaska to develop empirical relationships between SOC and stand and physiographic features. Total SOC harbored in mineral
soil horizons decreased by 4.4 g C m$^{-2}$ for every degree-day increase in heat sum within the organic soil across all
sites. Furthermore, the proportion of light fraction (density $<$1.6 g cm$^{-3}$) soil organic matter decreased
significantly with increased stand productivity and soil temperature. Mean residence times of SOC (as determined by
$\Delta$$^{14}$C) in dense fraction ($>$1.6 g cm$^{-3}$) mineral soil ranged from 282-672 years. The oldest SOC occurred in
the coolest sites, which also harbored the most C. These results suggest that temperature sensitivities of organic matter
within discrete soil pools, and not just total soil C stocks, need to be examined in order to project the effects of changing
climate and primary production on soil C balance.
DE: 1600 GLOBAL CHANGE (New category)
DE: 1615 Biogeochemical processes (4805)
DE: 0315 Biosphere/atmosphere interactions
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting