Jennifer Harden, PhD (Former Employee)
Science and Products
Filter Total Items: 134
Measurement of soil carbon oxidation state and oxidative ratio by 13C nuclear magnetic resonance
The oxidative ratio (OR) of the net ecosystem carbon balance is the ratio of net O2 and CO2 fluxes resulting from photosynthesis, respiration, decomposition, and other lateral and vertical carbon flows. The OR of the terrestrial biosphere must be well characterized to accurately estimate the terrestrial CO2 sink using atmospheric measurements of changing O2 and CO2 levels. To estimate the OR of th
Authors
W.C. Hockaday, C.A. Masiello, J. T. Randerson, R.J. Smernik, J.A. Baldock, O.A. Chadwick, J. W. Harden
Interactive effects of fire, soil climate, and moss on CO2 fluxes in black spruce ecosystems of interior Alaska
Fire is an important control on the carbon (C) balance of the boreal forest region. Here, we present findings from two complementary studies that examine how fire modifies soil organic matter properties, and how these modifications influence rates of decomposition and C exchange in black spruce (Picea mariana) ecosystems of interior Alaska. First, we used laboratory incubations to explore soil tem
Authors
J. A. O'Donnell, M.R. Turetsky, J. W. Harden, K.L. Manies, L.E. Pruett, G. Shetler, J. C. Neff
Effects of experimental water table and temperature manipulations on ecosystem CO2 fluxes in an Alaskan rich fen
Peatlands store 30% of the world's terrestrial soil carbon (C) and those located at northern latitudes are expected to experience rapid climate warming. We monitored growing season carbon dioxide (CO2) fluxes across a factorial design of in situ water table (control, drought, and flooded plots) and soil warming (control vs. warming via open top chambers) treatments for 2 years in a rich fen locate
Authors
M.R. Chivers, M.R. Turetsky, J. M. Waddington, J. W. Harden, A. D. McGuire
Linking soil organic matter dynamics and erosion-induced terrestrial carbon sequestration at different landform positions
Recently, the potential for terrestrial carbon (C) sequestration by soil erosion and deposition has received increased interest. Erosion and deposition constitute a sink for atmospheric carbon dioxide relative to a preerosional state or a noneroding scenario, if the posterosion watershed C balance is increased due to (1) partial replacement of eroded C by new photosynthate in the eroded site; and
Authors
Asmeret Asefaw Berhe, Jennifer W. Harden, Margaret S. Torn, John Harte
Boreal soil carbon dynamics under a changing climate: A model inversion approach
Several fundamental but important factors controlling the feedback of boreal organic carbon (OC) to climate change were examined using a mechanistic model of soil OC dynamics, including the combined effects of temperature and moisture on the decomposition of OC and the factors controlling carbon quality and decomposition with depth. To estimate decomposition rates and evaluate their variations wit
Authors
Zhaosheng Fan, Jason C. Neff, Jennifer W. Harden, Kimberly P. Wickland
Short-term response of methane fluxes and methanogen activity to water table and soil warming manipulations in an Alaskan peatland
Growing season CH4 fluxes were monitored over a two year period following the start of ecosystem-scale manipulations of water table position and surface soil temperatures in a moderate rich fen in interior Alaska. The largest CH4 fluxes occurred in plots that received both flooding (raised water table position) and soil warming, while the lowest fluxes occurred in unwarmed plots in the lowered wat
Authors
M. R. Turetsky, C. C. Treat, M. P. Waldrop, J. M. Waddington, Jennifer W. Harden, A. David McGuire
Soil erosion: data say C sink
No abstract available.
Authors
J. W. Harden, A.A. Berhe, M.S. Torn, J.J. Harte, Shu-Guang Liu, Robert F. Stallard
Recovery of aboveground plant biomass and productivity after fire in mesic and dry black spruce forests of interior Alaska
Plant biomass accumulation and productivity are important determinants of ecosystem carbon (C) balance during post-fire succession. In boreal black spruce (Picea mariana) forests near Delta Junction, Alaska, we quantified aboveground plant biomass and net primary productivity (ANPP) for 4 years after a 1999 wildfire in a well-drained (dry) site, and also across a dry and a moderately well-drained
Authors
M.C. Mack, K.K. Treseder, K.L. Manies, J. W. Harden, E.A.G. Schuur, J.G. Vogel, J. T. Randerson, F. S. Chapin
Interactive effects of wildfire and permafrost on microbial communities and soil processes in an Alaskan black spruce forest
Boreal forests contain significant quantities of soil carbon that may be oxidized to CO2 given future increases in climate warming and wildfire behavior. At the ecosystem scale, decomposition and heterotrophic respiration are strongly controlled by temperature and moisture, but we questioned whether changes in microbial biomass, activity, or community structure induced by fire might also affect th
Authors
M. P. Waldrop, J. W. Harden
Wetland succession in a permafrost collapse: Interactions between fire and thermokarst
To determine the influence of fire and thermokarst in a boreal landscape, we investigated peat cores within and adjacent to a permafrost collapse feature on the Tanana River Floodplain of Interior Alaska. Radioisotope dating, diatom assemblages, plant macrofossils, charcoal fragments, and carbon and nitrogen content of the peat profile indicate ???600 years of vegetation succession with a transiti
Authors
I. H. Myers-Smith, J. W. Harden, M. Wilmking, C. C. Fuller, A. D. McGuire, F. S. Chapin
Influence of disturbance on carbon exchange in a permafrost collapse and adjacent burned forest
We measured CO2 and CH4 exchange from the center of a Sphagnum‐dominated permafrost collapse, through an aquatic moat, and into a recently burned black spruce forest on the Tanana River floodplain in interior Alaska. In the anomalously dry growing season of 2004, both the collapse and the surrounding burned area were net sinks for CO2, with a mean daytime net ecosystem exchange of −1.4 μmol CO2 m−
Authors
I. H. Myers-Smith, A. D. McGuire, J. W. Harden, F. S. Chapin
The impact of agricultural soil erosion on the global carbon cycle
Agricultural soil erosion is thought to perturb the global carbon cycle, but estimates of its effect range from a source of 1 petagram per year–1 to a sink of the same magnitude. By using caesium-137 and carbon inventory measurements from a large-scale survey, we found consistent evidence for an erosion-induced sink of atmospheric carbon equivalent to approximately 26% of the carbon transported by
Authors
Kristof Van Oost, T.A. Quine, G. Govers, S. De Gryze, J. Six, J. W. Harden, J.C. Ritchie, G.W. McCarty, G. Heckrath, C. Kosmas, J.V. Giraldez, J.R. Marques Da Silva, R. Merckx
Science and Products
Filter Total Items: 134
Measurement of soil carbon oxidation state and oxidative ratio by 13C nuclear magnetic resonance
The oxidative ratio (OR) of the net ecosystem carbon balance is the ratio of net O2 and CO2 fluxes resulting from photosynthesis, respiration, decomposition, and other lateral and vertical carbon flows. The OR of the terrestrial biosphere must be well characterized to accurately estimate the terrestrial CO2 sink using atmospheric measurements of changing O2 and CO2 levels. To estimate the OR of th
Authors
W.C. Hockaday, C.A. Masiello, J. T. Randerson, R.J. Smernik, J.A. Baldock, O.A. Chadwick, J. W. Harden
Interactive effects of fire, soil climate, and moss on CO2 fluxes in black spruce ecosystems of interior Alaska
Fire is an important control on the carbon (C) balance of the boreal forest region. Here, we present findings from two complementary studies that examine how fire modifies soil organic matter properties, and how these modifications influence rates of decomposition and C exchange in black spruce (Picea mariana) ecosystems of interior Alaska. First, we used laboratory incubations to explore soil tem
Authors
J. A. O'Donnell, M.R. Turetsky, J. W. Harden, K.L. Manies, L.E. Pruett, G. Shetler, J. C. Neff
Effects of experimental water table and temperature manipulations on ecosystem CO2 fluxes in an Alaskan rich fen
Peatlands store 30% of the world's terrestrial soil carbon (C) and those located at northern latitudes are expected to experience rapid climate warming. We monitored growing season carbon dioxide (CO2) fluxes across a factorial design of in situ water table (control, drought, and flooded plots) and soil warming (control vs. warming via open top chambers) treatments for 2 years in a rich fen locate
Authors
M.R. Chivers, M.R. Turetsky, J. M. Waddington, J. W. Harden, A. D. McGuire
Linking soil organic matter dynamics and erosion-induced terrestrial carbon sequestration at different landform positions
Recently, the potential for terrestrial carbon (C) sequestration by soil erosion and deposition has received increased interest. Erosion and deposition constitute a sink for atmospheric carbon dioxide relative to a preerosional state or a noneroding scenario, if the posterosion watershed C balance is increased due to (1) partial replacement of eroded C by new photosynthate in the eroded site; and
Authors
Asmeret Asefaw Berhe, Jennifer W. Harden, Margaret S. Torn, John Harte
Boreal soil carbon dynamics under a changing climate: A model inversion approach
Several fundamental but important factors controlling the feedback of boreal organic carbon (OC) to climate change were examined using a mechanistic model of soil OC dynamics, including the combined effects of temperature and moisture on the decomposition of OC and the factors controlling carbon quality and decomposition with depth. To estimate decomposition rates and evaluate their variations wit
Authors
Zhaosheng Fan, Jason C. Neff, Jennifer W. Harden, Kimberly P. Wickland
Short-term response of methane fluxes and methanogen activity to water table and soil warming manipulations in an Alaskan peatland
Growing season CH4 fluxes were monitored over a two year period following the start of ecosystem-scale manipulations of water table position and surface soil temperatures in a moderate rich fen in interior Alaska. The largest CH4 fluxes occurred in plots that received both flooding (raised water table position) and soil warming, while the lowest fluxes occurred in unwarmed plots in the lowered wat
Authors
M. R. Turetsky, C. C. Treat, M. P. Waldrop, J. M. Waddington, Jennifer W. Harden, A. David McGuire
Soil erosion: data say C sink
No abstract available.
Authors
J. W. Harden, A.A. Berhe, M.S. Torn, J.J. Harte, Shu-Guang Liu, Robert F. Stallard
Recovery of aboveground plant biomass and productivity after fire in mesic and dry black spruce forests of interior Alaska
Plant biomass accumulation and productivity are important determinants of ecosystem carbon (C) balance during post-fire succession. In boreal black spruce (Picea mariana) forests near Delta Junction, Alaska, we quantified aboveground plant biomass and net primary productivity (ANPP) for 4 years after a 1999 wildfire in a well-drained (dry) site, and also across a dry and a moderately well-drained
Authors
M.C. Mack, K.K. Treseder, K.L. Manies, J. W. Harden, E.A.G. Schuur, J.G. Vogel, J. T. Randerson, F. S. Chapin
Interactive effects of wildfire and permafrost on microbial communities and soil processes in an Alaskan black spruce forest
Boreal forests contain significant quantities of soil carbon that may be oxidized to CO2 given future increases in climate warming and wildfire behavior. At the ecosystem scale, decomposition and heterotrophic respiration are strongly controlled by temperature and moisture, but we questioned whether changes in microbial biomass, activity, or community structure induced by fire might also affect th
Authors
M. P. Waldrop, J. W. Harden
Wetland succession in a permafrost collapse: Interactions between fire and thermokarst
To determine the influence of fire and thermokarst in a boreal landscape, we investigated peat cores within and adjacent to a permafrost collapse feature on the Tanana River Floodplain of Interior Alaska. Radioisotope dating, diatom assemblages, plant macrofossils, charcoal fragments, and carbon and nitrogen content of the peat profile indicate ???600 years of vegetation succession with a transiti
Authors
I. H. Myers-Smith, J. W. Harden, M. Wilmking, C. C. Fuller, A. D. McGuire, F. S. Chapin
Influence of disturbance on carbon exchange in a permafrost collapse and adjacent burned forest
We measured CO2 and CH4 exchange from the center of a Sphagnum‐dominated permafrost collapse, through an aquatic moat, and into a recently burned black spruce forest on the Tanana River floodplain in interior Alaska. In the anomalously dry growing season of 2004, both the collapse and the surrounding burned area were net sinks for CO2, with a mean daytime net ecosystem exchange of −1.4 μmol CO2 m−
Authors
I. H. Myers-Smith, A. D. McGuire, J. W. Harden, F. S. Chapin
The impact of agricultural soil erosion on the global carbon cycle
Agricultural soil erosion is thought to perturb the global carbon cycle, but estimates of its effect range from a source of 1 petagram per year–1 to a sink of the same magnitude. By using caesium-137 and carbon inventory measurements from a large-scale survey, we found consistent evidence for an erosion-induced sink of atmospheric carbon equivalent to approximately 26% of the carbon transported by
Authors
Kristof Van Oost, T.A. Quine, G. Govers, S. De Gryze, J. Six, J. W. Harden, J.C. Ritchie, G.W. McCarty, G. Heckrath, C. Kosmas, J.V. Giraldez, J.R. Marques Da Silva, R. Merckx
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government