Skip to main content
U.S. flag

An official website of the United States government

Jack McFarland

Jack is a Biologist with the Geology, Minerals, Energy, and Geophysics Science Center

Science and Products

link
patch of burned conifers in California

Response of plant, microbial, and soil functions to drought and fire in California

California is experiencing changes in precipitation and wildfire regimes. Longer, hotter fire seasons along with extremes in precipitation are expected to continue. Not only do these disturbances affect the productivity and resilience of ecosystems, they also directly impact human health and wellbeing. Soils hold an immense amount of our terrestrial carbon pool, and the microorganisms and minerals...
By
Climate Research and Development Program, Geology, Minerals, Energy, and Geophysics Science Center
link

Response of plant, microbial, and soil functions to drought and fire in California

California is experiencing changes in precipitation and wildfire regimes. Longer, hotter fire seasons along with extremes in precipitation are expected to continue. Not only do these disturbances affect the productivity and resilience of ecosystems, they also directly impact human health and wellbeing. Soils hold an immense amount of our terrestrial carbon pool, and the microorganisms and minerals...
Learn More
link
scientists collecting permafrost cores

Arctic Biogeochemical Response to Permafrost Thaw (ABRUPT)

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...
By
Climate Research and Development Program, Geology, Minerals, Energy, and Geophysics Science Center
link

Arctic Biogeochemical Response to Permafrost Thaw (ABRUPT)

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...
Learn More

Short vs intermediate-term fate of glucose and oxalic acid in surface and subsurface soils of a coastal grassland near Santa Cruz California

Though the primary sources of organic matter to soil are plant inputs, the role of microorganisms as mediators of soil organic carbon preservation is increasingly recognized in the context of biological contributions to long-lived soil organic matter. However, current knowledge of sub-soil processes is insufficient to model microbial-derived carbon flow particularly at depth. Using a previously st
By
Climate Research and Development Program, Geology, Minerals, Energy, and Geophysics Science Center

Permafrost greenhouse gas and microbial data from the Alaska Peatland Experiment (APEX) 2017 to 2019

These data include permafrost gas concentration data from the Alaska Peatland Experiment at various depths, times, and locations
By
Climate Research and Development Program, Geology, Minerals, Energy, and Geophysics Science Center

Permafrost characterization at the Alaska Peatland Experiment (APEX) site: Geophysical and related field data collected from 2018-2020

Geophysical measurements and related field data were collected by the U.S. Geological Survey (USGS) at the Alaska Peatland Experiment (APEX) site in Interior Alaska from 2018 to 2020 to characterize subsurface thermal and hydrologic conditions along a permafrost thaw gradient. The APEX site is managed by the Bonanza Creek LTER (Long Term Ecological Research). In April 2018, seven boreholes were em
By
Geology, Geophysics, and Geochemistry Science Center

Microbial Carbon and Nitrogen Metabolism Across a Late Pleistocene Permafrost Chronosequence

This data release includes all of the data presented in the peer-reviewed publication "Life at the frozen limit: Microbial Carbon Metabolism Across a Late Pleistocene Permafrost Chronosequence". We collected permafrost from a Pleistocene chronosequence (19 ka to 33 ka) to examine (1) changes in the functional genetic potential of extant microbial communities to metabolize polysaccharides, (2) shif
By
Geology, Minerals, Energy, and Geophysics Science Center
Filter Total Items: 13

The influence of soil development on the depth distribution and structure of soil microbial communities.

Although it has been shown that the interaction of climate and time shape the dynamics of soil organic matter (SOM) storage and preservation in soil, the role of soil microbial communities in this dynamic remains unclear. Microbial communities are present throughout soil profiles and likely play critical roles in SOM and nutrient cycling, however the influence of other factors such as soil develop
By
Climate Research and Development Program, Geosciences and Environmental Change Science Center

Mechanisms for retention of low molecular weight organic carbon varies with soil depth at a coastal prairie ecosystem

Though primary sources of carbon (C) to soil are plant inputs (e.g., rhizodeposits), the role of microorganisms as mediators of soil organic carbon (SOC) retention is increasingly recognized. Yet, insufficient knowledge of sub-soil processes complicates attempts to describe microbial-driven C cycling at depth as most studies of microbial-mineral-C interactions focus on surface horizons. We leverag
By
Volcano Hazards Program, Geology, Minerals, Energy, and Geophysics Science Center, Geosciences and Environmental Change Science Center, Volcano Science Center

The biophysical role of water and ice within permafrost nearing collapse: Insights from novel geophysical observations

The impact of permafrost thaw on hydrologic, thermal, and biotic processes remains uncertain, in part due to limitations in subsurface measurement capabilities. To better understand subsurface processes in thermokarst environments, we collocated geophysical and biogeochemical instruments along a thaw gradient between forested permafrost and collapse-scar bogs at the Alaska Peatland Experiment (APE
By
Climate Research and Development Program, Land Change Science Program, Geology, Geophysics, and Geochemistry Science Center

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 featu
By
Volcano Hazards Program, Geology, Minerals, Energy, and Geophysics Science Center, Volcano Science Center, Florence Bascom Geoscience Center

Life at the frozen limit: Microbial carbon metabolism across a Late Pleistocene permafrost chronosequence

Permafrost is an extreme habitat yet it hosts microbial populations that remain active over millennia. Using permafrost collected from a Pleistocene chronosequence (19 to 33 ka), we hypothesized that the functional genetic potential of microbial communities in permafrost would reflect microbial strategies to metabolize permafrost soluble organic matter (OM) in situ over geologic time. We also hypo
By
Climate Research and Development Program, Geology, Minerals, Energy, and Geophysics Science Center

Geese mediate vegetation state changes with parallel effects on N cycling that leave nutritional legacies for offspring

Along the coastal fringe of the Yukon–Kuskokwim River Delta in southwestern Alaska, geese maintain grazing lawns dominated by a rhizomatous sedge that, when ungrazed, transitions to a taller, less palatable growth form that is taxonomically described as a different species. Nutrients recycled in goose feces, in conjunction with grazing, are critical to the rapid, nutritious growth of grazing lawns
By
Geology, Minerals, Energy, and Geophysics Science Center

Large 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 flux
By
Climate Research and Development Program, Geology, Minerals, Energy, and Geophysics Science Center, Woods Hole Coastal and Marine Science Center

Mineralogy dictates the initial mechanism of microbial necromass association

Soil organic matter (SOM) improves soil fertility and mitigates disturbance related to climate and land use change. Microbial necromass (the accumulated cellular residues of microorganisms) comprises the majority of soil C, yet the formation and persistence of necromass in relation to mineralogy is poorly understood. We tested whether soil minerals had different microbial necromass association mec
By
Geology, Minerals, Energy, and Geophysics Science Center

Biological 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, w
By
Climate Research and Development Program, Land Change Science Program, Geology, Minerals, Energy, and Geophysics Science Center, Geosciences and Environmental Change Science Center

Warming effects of spring rainfall increase methane emissions from thawing permafrost

Methane emissions regulate the near‐term global warming potential of permafrost thaw, particularly where loss of ice‐rich permafrost converts forest and tundra into wetlands. Northern latitudes are expected to get warmer and wetter, and while there is consensus that warming will increase thaw and methane emissions, effects of increased precipitation are uncertain. At a thawing wetland complex in I
By
Natural Hazards Mission Area, Climate Research and Development Program, Land Change Science Program, Volcano Hazards Program, Volcano Science Center, Geology, Minerals, Energy, and Geophysics Science Center

Spatially explicit estimation of aboveground boreal forest biomass in the Yukon River Basin, Alaska

Quantification of aboveground biomass (AGB) in Alaska’s boreal forest is essential to the accurate evaluation of terrestrial carbon stocks and dynamics in northern high-latitude ecosystems. Our goal was to map AGB at 30 m resolution for the boreal forest in the Yukon River Basin of Alaska using Landsat data and ground measurements. We acquired Landsat images to generate a 3-year (2008–2010) compos
By
Earth Resources Observation and Science Center, Earth Resources Observation and Science (EROS) Center

Extreme CO2 disturbance and the resilience of soil microbial communities

Carbon capture and storage (CSS) technology has the potential to inadvertently release large quantities of CO2 through geologic substrates and into surrounding soils and ecosystems. Such a disturbance has the potential to not only alter the structure and function of plant and animal communities, but also soils, soil microbial communities, and the biogeochemical processes they mediate. At Mammoth
By
Volcano Hazards Program, Volcano Science Center

Science and Products