HR: 0800h
AN: B31B-0334    [Abstracts]
TI: Terrestrial Carbon Dynamics in Prairie Remnants and Conservation Reserve Program Lands of the Palouse Region
AU: * Sánchez-de León, Y
EM: ysl@uic.edu
AF: University of Illinois at Chicago, Department of Biological Sciences (MC 066), 845 West Taylor Street, Chicago, IL 60607, United States
AU: Johnson-Maynard, J
EM: jmaynard@uidaho.edu
AF: University of Idaho, Department of Plant, Soil and Entomological Sciences, Room 242, Moscow, ID 83844-2339,
AB: Conversion of marginal agricultural lands to perennial grassland vegetation has been proposed as a way to enhance terrestrial carbon sequestration. The Conservation Reserve Program (CRP) has facilitated this transition and promoted carbon sequestration in highly erodible agricultural lands of the Palouse Region of northern Idaho and eastern Washington. Currently little is known about the potential of these lands to act as a carbon sinks in this region. We studied terrestrial carbon dynamics in CRP set asides planted with exotic grasses and in native prairie remnants of the Palouse Region. To study plant decomposition, the species Festuca idahoensis and Symphoricarpos albus were used as representatives of the native prairie community and Bromus inermis was used for CRP sites. Above- and belowground net primary productivity (from 170.9 to 216.0 g m^-2 yr^-1) and litter fall (from 15.6 to 31.0 g m^-2 yr^-1) were similar between grassland types. However, root biomass, soil macroaggregates and soil carbon were higher in prairie remnants. Decomposition rates of leaf litter were not different among plant species, however root decomposition was slower in S. albus (k = 0.28 yr^-1) than in F. idahoensis (k = 0.56 yr^-1) or B. inermis (k = 0.64 yr^-1). These results demonstrate that aboveground processes and carbon inputs in CRP sites have reached similar levels to native prairies. However, belowground carbon pools (i.e. root biomass and soil carbon) are still higher in prairie remnants. Belowground decomposition rates were related to root chemical composition as S. albus roots had the highest lignin to nitrogen ratio. The results of this study suggest that efforts to promote carbon sequestration in CRP grasslands of the Palouse should be focused on belowground pools and processes. Management practices that could increase the amount of carbon sequestered in these CRP sites include increasing the amount of root biomass production through fertilization and increasing the density of plants with recalcitrant litter inputs.
DE: 0402 Agricultural systems
DE: 0410 Biodiversity
DE: 0428 Carbon cycling (4806)
DE: 0486 Soils/pedology (1865)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting