Jennifer Harden, PhD (Former Employee)
Science and Products
Filter Total Items: 134
Water and heat transport in boreal soils: Implications for soil response to climate change
Soil water content strongly affects permafrost dynamics by changing the soil thermal properties. However, the movement of liquid water, which plays an important role in the heat transport of temperate soils, has been under-represented in boreal studies. Two different heat transport models with and without convective heat transport were compared to measurements of soil temperatures in four boreal s
Authors
Z. Fan, J. C. Neff, J. W. Harden, T. Zhang, H. Veldhuis, C.I. Czimczik, G.C. Winston, J. A. O'Donnell
The effect of fire and permafrost interactions on soil carbon accumulation in an upland black spruce ecosystem of interior Alaska: Implications for post-thaw carbon loss
High‐latitude regions store large amounts of organic carbon (OC) in active‐layer soils and permafrost, accounting for nearly half of the global belowground OC pool. In the boreal region, recent warming has promoted changes in the fire regime, which may exacerbate rates of permafrost thaw and alter soil OC dynamics in both organic and mineral soil. We examined how interactions between fire and perm
Authors
J. A. O'Donnell, J. W. Harden, A. D. McGuire, M.Z. Kanevskiy, M.T. Jorgenson, X. Xu
Seasonal ice and hydrologic controls on dissolved organic carbon and nitrogen concentrations in a boreal-rich fen
[1] Boreal wetland carbon cycling is vulnerable to climate change in part because hydrology and the extent of frozen ground have strong influences on plant and microbial functions. We examined the response of dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) across an experimental manipulation of water table position (both raised and lowered water table treatments) in a boreal-rich
Authors
Evan S. Kane, Merritt R. Turetsky, Jennifer W. Harden, A. David McGuire, James Michael Waddington
The carbon budget of the northern cryosphere region
The northern cryosphere is undergoing substantial warming of permafrost and loss of sea ice. Release of stored carbon to the atmosphere in response to this change has the potential to affect the global climate system. Studies indicate that the northern cryosphere has been not only a substantial sink for atmospheric CO2 in recent decades, but also an important source of CH4 because of emissions fro
Authors
A. David McGuire, Robie W. Macdonald, Edward A.G. Schuur, Jennifer W. Harden, Peter Kuhry, Daniel J. Hayes, Torben R. Christensen, Martin Heimann
The role of mosses in ecosystem succession and function in Alaska’s boreal forest
Shifts in moss communities may affect the resilience of boreal ecosystems to a changing climate because of the role of moss species in regulating soil climate and biogeochemical cycling. Here, we use long-term data analysis and literature synthesis to examine the role of moss in ecosystem succession, productivity, and decomposition. In Alaskan forests, moss abundance showed a unimodal distribution
Authors
Merritt R. Turetsky, Michelle Mack, Teresa N. Hollingsworth, Jennifer W. Harden
Resilience and vulnerability of permafrost to climate change
The resilience and vulnerability of permafrost to climate change depends on complex interactions among topography, water, soil, vegetation, and snow, which allow permafrost to persist at mean annual air temperatures (MAATs) as high as +2 °C and degrade at MAATs as low as –20 °C. To assess these interactions, we compiled existing data and tested effects of varying conditions on mean annual surface
Authors
M.Torre Jorgenson, Vladimir Romanovsky, Jennifer W. Harden, Yuri Shur, Jonathan O'Donnell, Edward A.G. Schuur, Mikhail Kanevskiy, Sergei Marchenko
The role of soil drainage class in carbon dioxide exchange and decomposition in boreal black spruce (Picea mariana) forest stands
Black spruce (Picea mariana (Mill.) B.S.P.) forest stands range from well drained to poorly drained, typically contain large amounts of soil organic carbon (SOC), and are often underlain by permafrost. To better understand the role of soil drainage class in carbon dioxide (CO2) exchange and decomposition, we measured soil respiration and net CO2 fluxes, litter decomposition and litterfall rates, a
Authors
K.P. Wickland, J. C. Neff, J. W. Harden
Molecular investigations into a globally important carbon pool: Permafrost-protected carbon in Alaskan soils
The fate of carbon (C) contained within permafrost in boreal forest environments is an important consideration for the current and future carbon cycle as soils warm in northern latitudes. Currently, little is known about the microbiology or chemistry of permafrost soils that may affect its decomposition once soils thaw. We tested the hypothesis that low microbial abundances and activities in perma
Authors
M. P. Waldrop, K.P. Wickland, Rickie White, A.A. Berhe, J. W. Harden, V.E. Romanovsky
Changes in Species, Areal Cover, and Production of Moss across a Fire Chronosequence in Interior Alaska
In an effort to characterize the species and production rates of various upland mosses and their relationship to both site drainage and time since fire, annual net primary production of six common moss species was measured. Several stands located near Delta Junction, interior Alaska, were located. These stands ranged from one to 116 years since fire in well-drained (dry) and moderately to somewhat
Authors
J. W. Harden, J. Munster, K.L. Manies, M.C. Mack, J. L. Bubier
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
Jonathan A. O'Donnell, Merritt R. Turetsky, Jennifer W. Harden, Kristen L. Manies, L.E. Pruett, Gordon Shetler, Jason 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
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
Science and Products
Filter Total Items: 134
Water and heat transport in boreal soils: Implications for soil response to climate change
Soil water content strongly affects permafrost dynamics by changing the soil thermal properties. However, the movement of liquid water, which plays an important role in the heat transport of temperate soils, has been under-represented in boreal studies. Two different heat transport models with and without convective heat transport were compared to measurements of soil temperatures in four boreal s
Authors
Z. Fan, J. C. Neff, J. W. Harden, T. Zhang, H. Veldhuis, C.I. Czimczik, G.C. Winston, J. A. O'Donnell
The effect of fire and permafrost interactions on soil carbon accumulation in an upland black spruce ecosystem of interior Alaska: Implications for post-thaw carbon loss
High‐latitude regions store large amounts of organic carbon (OC) in active‐layer soils and permafrost, accounting for nearly half of the global belowground OC pool. In the boreal region, recent warming has promoted changes in the fire regime, which may exacerbate rates of permafrost thaw and alter soil OC dynamics in both organic and mineral soil. We examined how interactions between fire and perm
Authors
J. A. O'Donnell, J. W. Harden, A. D. McGuire, M.Z. Kanevskiy, M.T. Jorgenson, X. Xu
Seasonal ice and hydrologic controls on dissolved organic carbon and nitrogen concentrations in a boreal-rich fen
[1] Boreal wetland carbon cycling is vulnerable to climate change in part because hydrology and the extent of frozen ground have strong influences on plant and microbial functions. We examined the response of dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) across an experimental manipulation of water table position (both raised and lowered water table treatments) in a boreal-rich
Authors
Evan S. Kane, Merritt R. Turetsky, Jennifer W. Harden, A. David McGuire, James Michael Waddington
The carbon budget of the northern cryosphere region
The northern cryosphere is undergoing substantial warming of permafrost and loss of sea ice. Release of stored carbon to the atmosphere in response to this change has the potential to affect the global climate system. Studies indicate that the northern cryosphere has been not only a substantial sink for atmospheric CO2 in recent decades, but also an important source of CH4 because of emissions fro
Authors
A. David McGuire, Robie W. Macdonald, Edward A.G. Schuur, Jennifer W. Harden, Peter Kuhry, Daniel J. Hayes, Torben R. Christensen, Martin Heimann
The role of mosses in ecosystem succession and function in Alaska’s boreal forest
Shifts in moss communities may affect the resilience of boreal ecosystems to a changing climate because of the role of moss species in regulating soil climate and biogeochemical cycling. Here, we use long-term data analysis and literature synthesis to examine the role of moss in ecosystem succession, productivity, and decomposition. In Alaskan forests, moss abundance showed a unimodal distribution
Authors
Merritt R. Turetsky, Michelle Mack, Teresa N. Hollingsworth, Jennifer W. Harden
Resilience and vulnerability of permafrost to climate change
The resilience and vulnerability of permafrost to climate change depends on complex interactions among topography, water, soil, vegetation, and snow, which allow permafrost to persist at mean annual air temperatures (MAATs) as high as +2 °C and degrade at MAATs as low as –20 °C. To assess these interactions, we compiled existing data and tested effects of varying conditions on mean annual surface
Authors
M.Torre Jorgenson, Vladimir Romanovsky, Jennifer W. Harden, Yuri Shur, Jonathan O'Donnell, Edward A.G. Schuur, Mikhail Kanevskiy, Sergei Marchenko
The role of soil drainage class in carbon dioxide exchange and decomposition in boreal black spruce (Picea mariana) forest stands
Black spruce (Picea mariana (Mill.) B.S.P.) forest stands range from well drained to poorly drained, typically contain large amounts of soil organic carbon (SOC), and are often underlain by permafrost. To better understand the role of soil drainage class in carbon dioxide (CO2) exchange and decomposition, we measured soil respiration and net CO2 fluxes, litter decomposition and litterfall rates, a
Authors
K.P. Wickland, J. C. Neff, J. W. Harden
Molecular investigations into a globally important carbon pool: Permafrost-protected carbon in Alaskan soils
The fate of carbon (C) contained within permafrost in boreal forest environments is an important consideration for the current and future carbon cycle as soils warm in northern latitudes. Currently, little is known about the microbiology or chemistry of permafrost soils that may affect its decomposition once soils thaw. We tested the hypothesis that low microbial abundances and activities in perma
Authors
M. P. Waldrop, K.P. Wickland, Rickie White, A.A. Berhe, J. W. Harden, V.E. Romanovsky
Changes in Species, Areal Cover, and Production of Moss across a Fire Chronosequence in Interior Alaska
In an effort to characterize the species and production rates of various upland mosses and their relationship to both site drainage and time since fire, annual net primary production of six common moss species was measured. Several stands located near Delta Junction, interior Alaska, were located. These stands ranged from one to 116 years since fire in well-drained (dry) and moderately to somewhat
Authors
J. W. Harden, J. Munster, K.L. Manies, M.C. Mack, J. L. Bubier
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
Jonathan A. O'Donnell, Merritt R. Turetsky, Jennifer W. Harden, Kristen L. Manies, L.E. Pruett, Gordon Shetler, Jason 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
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
*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