Warming and thawing of permafrost soils in the Arctic is expected to become widespread over the coming decades. Permafrost thaw changes ecosystem structure and function, affects resource availability for wildlife and society, and decreases ground stability which affects human infrastructure. Since permafrost soils contain about half of the global soil carbon (C) pool, the magnitude of C losses from permafrost thaw are critically important to understanding the global carbon cycle, known as the permafrost carbon feedback. Recently wintertime processes have been shown to be a critical yet understudied component of the permafrost carbon feedback. Therefore our goal is to understand wintertime processes controlling greenhouse gas fluxes (CO2 and CH4) from thawing permafrost soils in Alaska. Specifically, we are interested in measuring and modelling the presence of small amounts of liquid water within frozen soils that can fuel large changes in soil microbial activity and winter greenhouse gas fluxes.
Statement of Problem: Up to half of the annual arctic methane (CH4) and carbon dioxide (CO2) flux from soils to the atmosphere occurs during the winter, but the exact source of greenhouse gas (GHG) and how its production or consumption might vary among stages of permafrost thaw or in different locations is poorly understood. Greenhouse gases in winter can come from the surface active layer (the zone of surface soil that thaws and refreezes each year), the underlying talik (a deeper zone of soil that never freezes and is potentially a year-round source of microbial activity), and/or the deeper permafrost which, if near 0 °C, can contain significant amounts of unfrozen water (Figure 1).
Why this Research is Important: Our research improves the fundamental understanding of the processes that control greenhouse gas fluxes from northern ecosystems. Because wintertime processes are not well understood, these data will be very useful for understanding annual rates of greenhouse gas fluxes. Also, it will be useful to understand and model how processes occurring in different ecosystems that have different rates of thaw, or amount of snow cover, or soil chemistry may impact greenhouse gas production and therefore carbon budgets. By improving our understanding of the wintertime processes, permafrost change, and the fundamental processes that govern carbon storage and release from soils, we can improve predictions of the permafrost carbon feedback and future changes in ecosystems.
Our work and involvement with national and international scientists and agencies is very important. It helps us create products and models that allow scientists to be able to understand and forecast changes at global scales. Some of these collaborations include work with the International Soil Carbon Network, the Permafrost Carbon Network, the Long-Term Ecological Research Network, USGS Climate Adaptation Science Centers, the North American Carbon Program, the International Permafrost Association, the U.S. Department of Agriculture, and NASA.
Objective(s): Our primary objectives are to quantify the sources of winter greenhouse gas fluxes in locations that have minimal permafrost thaw and sites that have extensive permafrost thaw. As such we plan to understand rates of microbial activities and rates of gas diffusion through different zones of the soils (active layer, talik, and permafrost) from different landscape settings. We also propose to understand how differences in flux rates between different aged permafrost soils may be due to differences in the chemistry or microbiology of permafrost soils.
Methods: Our work will be conducted at several locations near Fairbanks, Alaska. Foremost is a site called the Alaska Peatland Experiment (APEX), where shallow (< 3 m deep) permafrost is near 0 ⁰C and has warmed over the recent decade producing active layer deepening greater than 50 cm. APEX has been well-characterized with flux towers, autochambers, soil temperature and moisture records, as well as with multiple geophysical methods. At this site, we have employed electrical resistivity tomography (ERT), nuclear magnetic resonance (NMR), and passive seismic techniques to provide insights into spatial and temporal patterns of ice and water within the near surface soil profile, established multiple systems for winter GHG flux monitoring, and established methodologies to examine microbial activities within frozen permafrost soils. Other sites to be included are located near Smith Lake and Goldstream Valley, AK. These sites will allow us to conduct gas diffusion experiments through permafrost, and compare young permafrost at APEX to older permafrost from the Goldstream Valley.
Below are publications associated with this project.
Influence of permafrost type and site history on losses of permafrost carbon after thaw
Carbon fluxes and microbial activities from boreal peatlands experiencing permafrost thaw
Permafrost mapping with electrical resistivity tomography in two wetland systems north of the Tanana River, Interior Alaska
Generalized models to estimate carbon and nitrogen stocks of organic soil horizons in Interior Alaska
Large loss of CO2 in winter observed across pan-arctic permafrost region
Towards determining spatial methane distribution on Arctic permafrost bluffs with an unmanned aerial system
Changes in the active, dead, and dormant microbial community structure across a Pleistocene permafrost chronosequence
Effect of permafrost thaw on plant and soil fungal community in the boreal forest: Does fungal community change mediate plant productivity response?
Biological and mineralogical controls over cycling of low molecular weight organic compounds along a soil chronosequence
Executive summary. In Second State of the Carbon Cycle Report (SOCCR2): A Sustained Assessment Report
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- Overview
Warming and thawing of permafrost soils in the Arctic is expected to become widespread over the coming decades. Permafrost thaw changes ecosystem structure and function, affects resource availability for wildlife and society, and decreases ground stability which affects human infrastructure. Since permafrost soils contain about half of the global soil carbon (C) pool, the magnitude of C losses from permafrost thaw are critically important to understanding the global carbon cycle, known as the permafrost carbon feedback. Recently wintertime processes have been shown to be a critical yet understudied component of the permafrost carbon feedback. Therefore our goal is to understand wintertime processes controlling greenhouse gas fluxes (CO2 and CH4) from thawing permafrost soils in Alaska. Specifically, we are interested in measuring and modelling the presence of small amounts of liquid water within frozen soils that can fuel large changes in soil microbial activity and winter greenhouse gas fluxes.
Statement of Problem: Up to half of the annual arctic methane (CH4) and carbon dioxide (CO2) flux from soils to the atmosphere occurs during the winter, but the exact source of greenhouse gas (GHG) and how its production or consumption might vary among stages of permafrost thaw or in different locations is poorly understood. Greenhouse gases in winter can come from the surface active layer (the zone of surface soil that thaws and refreezes each year), the underlying talik (a deeper zone of soil that never freezes and is potentially a year-round source of microbial activity), and/or the deeper permafrost which, if near 0 °C, can contain significant amounts of unfrozen water (Figure 1).
Figure 1. Characterization of the ecosystem transitions studied in this experiment and their influence on talik development and greenhouse gas production. Four sites herein are 1) permafrost plateaus with stable permafrost and therefore no talik development, 2) permafrost plateaus with observed talik development, 3) bog system with talik underlain by permafrost, and 4) fen ecosystem with deep talik and no permafrost. As taliks increase in size we expect increasing winter greenhouse gas emissions. Ice-rich permafrost cross section. Why this Research is Important: Our research improves the fundamental understanding of the processes that control greenhouse gas fluxes from northern ecosystems. Because wintertime processes are not well understood, these data will be very useful for understanding annual rates of greenhouse gas fluxes. Also, it will be useful to understand and model how processes occurring in different ecosystems that have different rates of thaw, or amount of snow cover, or soil chemistry may impact greenhouse gas production and therefore carbon budgets. By improving our understanding of the wintertime processes, permafrost change, and the fundamental processes that govern carbon storage and release from soils, we can improve predictions of the permafrost carbon feedback and future changes in ecosystems.
Our work and involvement with national and international scientists and agencies is very important. It helps us create products and models that allow scientists to be able to understand and forecast changes at global scales. Some of these collaborations include work with the International Soil Carbon Network, the Permafrost Carbon Network, the Long-Term Ecological Research Network, USGS Climate Adaptation Science Centers, the North American Carbon Program, the International Permafrost Association, the U.S. Department of Agriculture, and NASA.
Objective(s): Our primary objectives are to quantify the sources of winter greenhouse gas fluxes in locations that have minimal permafrost thaw and sites that have extensive permafrost thaw. As such we plan to understand rates of microbial activities and rates of gas diffusion through different zones of the soils (active layer, talik, and permafrost) from different landscape settings. We also propose to understand how differences in flux rates between different aged permafrost soils may be due to differences in the chemistry or microbiology of permafrost soils.
USGS researchers Jack McFarland and Kristen Manies taking permafrost cores to study the carbon cycle in Interior Alaska. Aseptic sampling of a permafrost core for DNA analysis. Methods: Our work will be conducted at several locations near Fairbanks, Alaska. Foremost is a site called the Alaska Peatland Experiment (APEX), where shallow (< 3 m deep) permafrost is near 0 ⁰C and has warmed over the recent decade producing active layer deepening greater than 50 cm. APEX has been well-characterized with flux towers, autochambers, soil temperature and moisture records, as well as with multiple geophysical methods. At this site, we have employed electrical resistivity tomography (ERT), nuclear magnetic resonance (NMR), and passive seismic techniques to provide insights into spatial and temporal patterns of ice and water within the near surface soil profile, established multiple systems for winter GHG flux monitoring, and established methodologies to examine microbial activities within frozen permafrost soils. Other sites to be included are located near Smith Lake and Goldstream Valley, AK. These sites will allow us to conduct gas diffusion experiments through permafrost, and compare young permafrost at APEX to older permafrost from the Goldstream Valley.
- Multimedia
- Publications
Below are publications associated with this project.
Influence of permafrost type and site history on losses of permafrost carbon after thaw
We quantified permafrost peat plateau and post-thaw carbon (C) stocks across a chronosequence in Interior Alaska to evaluate the amount of C lost with thaw. Macrofossil reconstructions revealed three stratigraphic layers of peat: (1) a base layer of fen/marsh peat, (2) peat from a forested peat plateau (with permafrost) and, (3) collapse-scar bog peat (at sites where permafrost thaw has occurred).Carbon fluxes and microbial activities from boreal peatlands experiencing permafrost thaw
Permafrost thaw in northern ecosystems may cause large quantities of carbon (C) to move from soil to atmospheric pools. Because soil microbial communities play a critical role in regulating C fluxes from soils, we examined microbial activity and greenhouse gas production soon after permafrost thaw and ground collapse (into collapse-scar bogs), relative to the permafrost plateau or older thaw featuPermafrost mapping with electrical resistivity tomography in two wetland systems north of the Tanana River, Interior Alaska
Surface-based 2D electrical resistivity tomography (ERT) surveys were used to characterize permafrost distribution at wetland sites on the alluvial plain north of the Tanana River, 20 km southwest of Fairbanks, Alaska, in June and September 2014. The sites were part of an ecologically-sensitive research area characterizing biogeochemical response of this region to warming and permafrost thaw, andGeneralized models to estimate carbon and nitrogen stocks of organic soil horizons in Interior Alaska
Boreal ecosystems comprise one tenth of the world’s land surface and contain over 20 % of the global soil carbon (C) stocks. Boreal soils are unique in that its mineral soil is covered by what can be quite thick layers of organic soil. These organic soil layers, or horizons, can differ in their state of decomposition, source vegetation, and disturbance history. These differences result in varyingLarge loss of CO2 in winter observed across pan-arctic permafrost region
Recent warming in the Arctic, which has been amplified during the winter1,2,3, greatly enhances microbial decomposition of soil organic matter and subsequent release of carbon dioxide (CO2)4. However, the amount of CO2 released in winter is not known and has not been well represented by ecosystem models or empirically based estimates5,6. Here we synthesize regional in situ observations of CO2 fluxTowards determining spatial methane distribution on Arctic permafrost bluffs with an unmanned aerial system
Arctic permafrost stores vast amounts of methane (CH4) in subsurface reservoirs. Thawing permafrost creates areas for this potent greenhouse gas to be released to the atmosphere. Identifying ‘hot spots’ of methane flux on a local scale has been limited by the spatial scales of traditional ground-based or satellite-based methane-sampling methods. Here we present a reliable and an easily replicableChanges in the active, dead, and dormant microbial community structure across a Pleistocene permafrost chronosequence
Permafrost hosts a community of microorganisms that survive and reproduce for millennia despite extreme environmental conditions such as water stress, subzero temperatures, high salinity, and low nutrient availability. Many studies focused on permafrost microbial community composition use DNA-based methods such as metagenomic and 16S rRNA gene sequencing. However, these methods do not distinguishEffect of permafrost thaw on plant and soil fungal community in the boreal forest: Does fungal community change mediate plant productivity response?
Permafrost thaw is leading to rapid shifts in boreal ecosystem function. Permafrost thaw affects soil carbon turnover through changes in soil hydrology, however, the biotic mechanisms regulating plant community response remain elusive. Here, we measured the response of fungal community composition and soil nutrient content in an intact permafrost plateau forest soil and an adjacent thermokarst bogBiological and mineralogical controls over cycling of low molecular weight organic compounds along a soil chronosequence
Low molecular weight organic compounds (LMWOC) represent a small but critical component of soil organic matter (SOM) for microbial growth and metabolism. The fate of these compounds is largely under microbial control, yet outside the cell, intrinsic soil properties can also significantly influence their turnover and retention. Using a chronosequence representing 1200 ka of pedogenic development, wExecutive summary. In Second State of the Carbon Cycle Report (SOCCR2): A Sustained Assessment Report
Central to life on Earth, carbon is essential to the molecular makeup of all living things and plays a key role in regulating global climate. To understand carbon’s role in these processes, researchers measure and evaluate carbon stocks and fluxes. A stock is the quantity of carbon contained in a pool or reservoir in the Earth system (e.g., carbon in forest trees), and a flux is the direction and - Partners
Below are partners associated with this project.
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