About

Thea Whitman is a Visiting Associate Professor in the Department of Soil and Environmental Sciences at the University of Wisconsin-Madison. Her research focuses on soil microbial ecology, organic matter decomposition and carbon stabilization, and the impacts of global environmental change. She investigates the linking of microbial community functions with ecosystem processes, including the effects of fire on soil carbon and microbes, utilizing stable isotopes to understand these dynamics. Her work aims to elucidate the role of soil microbes in environmental processes and inform management and policy decisions related to soil and ecosystem health.

Research topics

• Biology
• Genetics
• Computational biology
• Ecology
• Computer Science
• Evolutionary biology
• Environmental science
• Chemistry
• Social Science
• Sociology
• Agronomy
• Astronomy
• Environmental planning
• Library science
• Engineering
• Physics
• Data science
• Waste management
• Environmental ethics
• World Wide Web
• Business
• Environmental resource management
• Economics
• Natural resource economics

Selected publications

• Stand age and fire return interval shape soil microbial communities in young, postfire lodgepole pine stands

  Soil Biology and Biochemistry · 2026-01-28

  article
  PublisherDOI

• Biotic responses to fire disturbance in Canada

  Environmental Reviews · 2026-01-01 · 1 citations

  articleOpen access

  Wildfires are ecological disturbances that drive rapid and often long-lasting changes to biological communities in forest ecosystems. This review synthesizes post-fire responses across microbial (fungi and bacteria), insect and other invertebrate, landbird, forest-dwelling mammal, and aquatic communities, with an emphasis on Canadian forest ecosystems. Taxa show variable spatial and temporal responses to fire, with some exhibiting obvious fire-adapted traits or behaviour and others appearing less resistant or resilient, or both. While advances in molecular tools have significantly enhanced capabilities for detecting and characterizing microbial community responses to disturbance, overall, their responses remain generally understudied in Canada, particularly outside of western boreal forests. Insect responses range from mortality and habitat loss to population increases in fire-adapted species, with fire-insect feedback becoming increasingly important under climate change. Landbird communities show species- and region-specific responses to fire severity and time since burn, but long-term demographic data are lacking. Mammal responses vary widely depending on factors such as mobility, habitat requirements, and post-fire landscape configuration, and include at-risk species facing compounding threats from habitat fragmentation, salvage harvesting, and climate change. Aquatic biota likewise exhibit mixed responses to fire, ranging from increased productivity to declines that are driven by changes in water quality, temperature, and sedimentation. The prospect of more frequent large, high-severity wildfires highlights the need for a better understanding of ecological resilience and vulnerability. Critical research gaps include the need for more integrated, multi-taxa studies to inform conservation planning and fire management across diverse Canadian landscapes.

  PublisherDOI

• Burn-induced decreases in soil microbial carbon use efficiency vary across soil types and substrates

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-08-02

  preprintOpen accessSenior authorCorresponding

  Abstract Wildfires cause immediate changes in above and belowground carbon (C) stocks in boreal forest ecosystems with long-term repercussions for C cycling. Understanding the role of soil microbes in mediating post-fire C cycling and recovery is an important step to predicting how these ecosystems will respond to novel wildfire regimes caused by climate change. Wildfires can cause large shifts in soil bacterial and fungal community composition that can persist for years post-fire. Less is known about the effects of fire on soil microbial community function, such as C use efficiency (CUE). In this study, we measured the effects of burning on substrate-specific CUE using a laboratory incubation of boreal forest soils. We amended burned and unburned soils with either 13 C-labelled ground pine roots or glucose and measured the amount of added substrate C that was incorporated into microbial biomass C versus respired as CO 2 in order to calculate CUE. Burning caused a decrease in the amount of soil microbial biomass and respiration derived from soil organic C. Glucose-specific CUE declined with burning, driven by a decrease in glucose-derived microbial biomass. This decrease in glucose-specific CUE following burning correlated with an increase in weighted mean predicted 16S rRNA gene copy number, raising the possibility of using copy number as a proxy for post-fire CUE in boreal forest soils. Overall, pine-specific CUE was lower than glucose-specific CUE, likely reflecting the difference in chemical complexity between the two substrates; burning had a much smaller effect on pine-specific CUE, highlighting the variability of CUE between substrates in burned soils.

  PublisherOA PDFDOI

• Resilience not yet apparent in soil fungal communities of the boreal forest from one to five years after wildfire across a severity gradient

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-03-29 · 2 citations

  preprintOpen access1st authorCorresponding

  Abstract Wildfires are natural disturbances characteristic of boreal forests. However, fire regimes around the world are changing, with effects on fire frequency and fire severity. Here, we present data from one and five years post-fire across 40 different sites from the boreal forest of the Northwest Territories and Alberta, Canada, asking the following questions: (1) Do the factors that structure post-fire soil fungal communities change over time? (2) Is there evidence for resilience in fungal community composition across different burn severities? (3) Do fire-enriched taxa change one vs. five years post-fire? Factors correlated with fungal community composition remain largely the same five years post-fire, with a declining correlation with burned/unburned, and an increasing association with vegetation community composition. This suggests that the immediate effects of fire on fungal community composition wane or diverge with time, while the influence of longer-term effects of fire, such as changes in vegetation, increases. Fungal communities failed to demonstrate resilience in community composition five years post-fire, in contrast to our findings for bacterial communities, and suggesting that fungal communities may be more closely tied to soil properties and vegetation communities that take longer to recover post-fire. Finally, we identify and classify fire-responsive fungi into different response types, based on their enrichment or depletion one vs. five years post fire. Persistent fire responders include taxa from the genera Penicillium , Coniochaeta , and Calyptrozyma , and the family Venturiaceae , but different taxa within a single genus respond differently to fires, underscoring that generalizations even at relatively fine taxonomic levels may be inappropriate, and that the mere presence of traits that may be relevant to post-fire success are insufficient alone to guarantee post-fire abundance. Future manipulative and observational studies will help us continue to dissect the multiple factors and traits structuring fungal responses to fires.

  PublisherOA PDFDOI

• Dissection of Carbon and Nitrogen Cycling in Post-Fire Soil Environments using a Genome- Informed Experimental Community (Final Technical Report)

  2025-01-01

  reportOpen access1st authorCorresponding

  Wildfires are a natural part of many forest ecosystems, with globally important carbon (C) storage and nutrient cycling consequences, and they are increasing in frequency and severity in Western North America. Forest fires affect soil C stocks in complex ways; some C is released into the atmosphere through combustion, while a large percentage of the C is added to the soil in the form of pyrogenic organic matter. Worldwide, it is estimated that 16% of soil organic matter is pyrogenic, while locally, this number may be as high as 80%. Understanding how wildfires affect soil organic matter cycling requires understanding how microbes respond to pyrogenic organic matter and other post-fire soil conditions. However, our understanding of microbial interactions within post-fire soil was in its infancy at the time of our proposal. Outstanding questions included: Which microbes are capable of degrading pyrogenic organic matter? What are the relevant genes and metabolites associated with this degradation? What are the key interactions among post-fire microbes? Key highlights of outcomes supported by this grant included training eleven early-career scientists and two early-career PIs, publication of twelve peer-reviewed papers, cross-lab collaborations that empowered complex scientific approaches, the development of an open-source automated gas sampler to drive novel insights in C cycling, enhanced understanding of post-fire microbial community dynamics, and novel genetic and molecular insights into microbial responses to fire.

  PublisherOA PDFDOI

• Fire removes preexisting pyrogenic organic matter from the ecosystem through the mechanisms of both direct combustion and increasing mineralizability

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-12-05

  articleOpen accessSenior authorCorresponding

  Abstract Pyrogenic organic matter (PyOM) produced during fires plays an important role in the global carbon (C) cycle due to its low microbial availability and resulting high persistence. However, PyOM can be combusted or chemically altered in subsequent fires. To explore the effect of subsequent fire on PyOM, we used a mass loss calorimeter to deliver realistic heat fluxes to jack pine ( Pinus banksiana Lamb.) PyOM produced at 350 °C, testing heat flux profiles (High, Low, and Control) and burial depths (Surface, 1 cm, and 5 cm) in a full-factorial design. We found that both variables significantly affected the C remaining after burns ( p < 0.05), with greater C losses at higher heat fluxes and shallower exposure depths. Consistent with our predictions, treatments with high heat exposure (HF High +Surface, HF High +1cm, HF Low +Surface) showed increases in pH and decreases in total dissolved organic carbon (DOC) and mineralized C after the subsequent fire. Counter to our predictions, treatments with intermediate heat exposure (HF High +5cm and HF Low +1cm) caused significant decreases in pH and increases in DOC, mineralized C, modelled decomposable C, and modelled C decomposition rate ( p < 0.05), compared to the unburned controls. These findings highlight that, despite its high persistence in fire-free conditions, PyOM is readily combusted and altered in subsequent fires, with important implications for changing fire regimes and the global C cycle. Synopsis Statement Subsequent fires not only consume PyOM produced in previous burns, but can also increase its susceptibility to microbial decomposition, which challenges the potential for PyOM to contribute to long-term carbon storage.

  PublisherDOI

• Reburning pyrogenic organic matter: a laboratory method for dosing dynamic heat fluxes from above

  International Journal of Wildland Fire · 2025-03-18 · 1 citations

  articleOpen accessSenior authorCorresponding

  Background Pyrogenic organic matter (PyOM) represents a relatively persistent component of soil carbon stocks. Although subsequent fires have the potential to combust or alter preexisting PyOM stocks, simulating soil heating faces important methodological constraints. In particular, methods for estimating the effects of subsequent fire on preexisting PyOM in soil have important limitations. Aims We aimed to design a laboratory method to effectively simulate soil heating from above, to investigate the impacts of subsequent fires on PyOM at different soil depths while addressing key limitations of previous methods. Methods Jack pine (Pinus banksiana Lamb.) log burns were used to parameterise realistic heat flux profiles. Using a cone calorimeter, these profiles were applied to buried jack pine PyOM to simulate variable reburn fire intensities. Key results In general, higher heat fluxes and shallower depths led to more mass loss of PyOM. Conclusions We offer a method to simulate specific soil heating profiles. Conditions that result in higher temperatures (higher heat fluxes and shallower depths) are likely to lead to more loss of PyOM in subsequent fires. Implications The method could simulate different fire scenarios to represent spatial variability within a given fire event, or to study the effects of fire on different types of biomass, or organisms such as microbes.

  PublisherOA PDFDOI

• Soil:Micro – A free data-based virtual reality experience of soil at a microbial scale

  Pedobiologia · 2025-03-30

  articleOpen access1st authorCorresponding

  Soil ecologists face a particular challenge in visualizing the environment that soil organisms inhabit, as it is both opaque and microscopic. We have developed a virtual reality (VR) experience of a soil at a microbial scale, based on a micro-computed tomography scan of a real soil. The VR app Soil:Micro is designed for a head-mounted display and could be used in educational and public outreach settings. Users travel through a series of stations where they can explore the soil environment as they learn about soil as a habitat for soil microbes. We hope that this tool inspires interest in and knowledge about soils, helping both to combat “soil blindness” in the general public and also to inspire soil ecologists to see these complex ecosystems in new ways. • We present Soil:Micro, a virtual reality experience of soil at a microbial scale. • The VR soil environment is derived from micro-computed tomography data of a real soil. • We include suggestions for use of the tool in educational and outreach settings.

  PublisherDOI

• Complex effects of a prescribed burn on a prairie soil bacterial community

  Soil Biology and Biochemistry · 2025-12-05 · 2 citations

  articleCorresponding
  PublisherDOI

• Corrigendum to “An open-source, automated, gas sampling peripheral for laboratory incubation experiments using cavity ring-down spectroscopy” [HardwareX 10 (2021) e00208]

  HardwareX · 2024-02-09

  erratumOpen accessSenior author

  The authors regret that there is a flaw in the circuit described in Section 3.3 and depicted in Figs. 7 and 8 of the manuscript. This design bypasses the Schottky diode and risks exposure of the relay control board to voltage spikes caused by the deactivation of the sampling solenoids. To correct this issue, we recommend that the circuit be updated as follows:1.Ensure all equipment is powered off.2.Remove the black wires connecting the solenoids to the negative (-) rail of the connection board.3.Reconnect the black wires from the solenoids to a connection on the cathode side of the diode. In the example below we use contacts in column C for this connection.4.Using a 2 cm length of black wire, bridge the connection between the cathode side of the diode and the negative (-) rail of the connection board. In the example below we use the contact in column A to make this connection.5.Repeat steps 3 and 4 for each solenoid pair. The authors would like to apologise for any inconvenience caused. An open-source, automated, gas sampling peripheral for laboratory incubation experiments using cavity ring-down spectroscopyHardwareXVol. 10PreviewThe availability of cavity ring-down spectroscopic (CRDS) and off-axis cavity spectroscopic instruments has resulted in major changes in the way trace gas fluxes and isotopic composition are measured [1,2]. In the past, isotopic and trace gas measurements required gas capture in the field and subsequent analysis by isotope ratio mass spectrometer (IRMS) and/or gas chromatograph in the lab. While these techniques are still the gold standard for accuracy and precision, IRMS and gas chromatography are limited by their expense and limitations on sampling frequency and duration [3,4]. Full-Text PDF Open Access

  PublisherOA PDFDOI

Frequent coauthors

• Si Gao

  California State University, Sacramento

  396 shared

• Jessica Miesel

  265 shared

• Marija Veličković

  Environmental Molecular Sciences Laboratory

  264 shared

• Lauren Vega

  Environmental Molecular Sciences Laboratory

  264 shared

• Andrew Lipton

  Environmental Molecular Sciences Laboratory

  139 shared

• Michael SanClements

  National Ecological Observatory Network

  132 shared

• Robert Young

  132 shared

• Nancy Hess

  Environmental Molecular Sciences Laboratory

  132 shared

Labs

• Whitman LabPI