Davidson, Eric: UMCES Appalacian Lab (Project Lead)
Project Funding:
2014 - 2017
NRA: 2013 NASA: Carbon Cycle Science
Funded by USDA
Abstract:
Global soil carbon stocks are 2-4 times greater than atmospheric CO2-C. Soils and
wetlands are significant sources and sinks for atmospheric CO2, CH4 and N2O. Soil
greenhouse gas (GHG) emissions are likely to play a significant role as biotic feedbacks to
climate change. However, these complex processes, involving carbon, nitrogen, and
oxygen substrates and inhibitors, interactions with plant processes, and environmental
influences of temperature, moisture, and gas transport, remain challenging to simulate in
earth system models. Here we propose a novel integration of measurement and modeling of
these three GHGs in upland and wetland soils at the Howland Forest AmeriFlux site. Our
main objective is to improve understanding of and modeling capacity for interactions of
belowground temperature, moisture, and substrate supply as controllers of net soil
emissions of CO2, CH4, and N2O. The proposed work is central to Theme 3, as we seek to
refine the understanding of critical belowground soil processes, but is also relevant to
Theme 1 due to the boreal-temperate transition forest locale, Theme 2 because of the
upland-wetland transitions, and Theme 6 due to applicability of modeling to Ameriflux and
NACP networks.
Because the processes of CO2, CH4, and N2O production and consumption are inter-linked
through some common substrates and the contrasting effects of O2 as either an essential
substrate or a potential inhibitor, the mechanistic simulation of fluxes of any one gas must
be consistent with mechanistic simulations and observations of fluxes of the other gases.
Simulating the fluxes of one gas alone would be a simpler task, but simulating all three
gases simultaneously and linking to aboveground processes of carbon supply provides multiple constraints and affords greater confidence that the most important mechanisms are
aptly simulated. We take advantage of a data-rich study site, including ongoing NASA and
DOE funded measurements of soil profiles, chamber fluxes, eddy covariance fluxes, forest
inventory and biomass growth, leaf area, litterfall, and other ecosystem data at Howland, to
build and test an integrated modeling framework, adding functions and complexity of
model structure as warranted by the data-model fusion.
Global soil carbon stocks are 2-4 times greater than atmospheric CO2-C. Soils and
wetlands are significant sources and sinks for atmospheric CO2, CH4 and N2O. Soil
greenhouse gas (GHG) emissions are likely to play a significant role as biotic feedbacks to
climate change. However, these complex processes, involving carbon, nitrogen, and
oxygen substrates and inhibitors, interactions with plant processes, and environmental
influences of temperature, moisture, and gas transport, remain challenging to simulate in
earth system models. Here we propose a novel integration of measurement and modeling of
these three GHGs in upland and wetland soils at the Howland Forest AmeriFlux site. Our
main objective is to improve understanding of and modeling capacity for interactions of
belowground temperature, moisture, and substrate supply as controllers of net soil
emissions of CO2, CH4, and N2O. The proposed work is central to Theme 3, as we seek to
refine the understanding of critical belowground soil processes, but is also relevant to
Theme 1 due to the boreal-temperate transition forest locale, Theme 2 because of the
upland-wetland transitions, and Theme 6 due to applicability of modeling to Ameriflux and
NACP networks.
Because the processes of CO2, CH4, and N2O production and consumption are inter-linked
through some common substrates and the contrasting effects of O2 as either an essential
substrate or a potential inhibitor, the mechanistic simulation of fluxes of any one gas must
be consistent with mechanistic simulations and observations of fluxes of the other gases.
Simulating the fluxes of one gas alone would be a simpler task, but simulating all three
gases simultaneously and linking to aboveground processes of carbon supply provides multiple constraints and affords greater confidence that the most important mechanisms are
aptly simulated. We take advantage of a data-rich study site, including ongoing NASA and
DOE funded measurements of soil profiles, chamber fluxes, eddy covariance fluxes, forest
inventory and biomass growth, leaf area, litterfall, and other ecosystem data at Howland, to
build and test an integrated modeling framework, adding functions and complexity of
model structure as warranted by the data-model fusion.