About

Margaret Zimmer is an Associate Professor in the Department of Soil and Environmental Sciences at the University of Wisconsin-Madison. Her research focuses on soil physics, physical and chemical hydrology, watershed hydrology, hillslope hydrology, runoff generation, critical zone science, water quality, surface water-groundwater interactions, wetlands, nutrient cycling, and biogeochemistry. She is actively recruiting graduate students and is involved in research related to watersheds, hydrology, and water resources. Her work includes studying soil physics and the interactions within the water cycle, contributing to a better understanding of hydrological processes and environmental management.

Research topics

• Computer Science
• Geology
• Geography
• Ecology
• Environmental science
• Environmental resource management
• Cartography
• Climatology
• Sociology
• Water resource management
• Physics
• Biology
• Physical geography
• Mechanics
• Oceanography
• Geotechnical engineering
• Meteorology
• Environmental planning

Selected publications

• Identifying Headwater Streams across the Conterminous United States

  Ecosystems · 2026-01-13 · 1 citations

  articleSenior author
  PublisherDOI

• Drilling Within the Critical Zone

  Hydrological Processes · 2026-03-01 · 1 citations

  articleOpen access

  ABSTRACT The critical zone (CZ), extending from the vegetation canopy to the base of weathered material or depth of groundwater, hosts coupled hydrologic, geochemical, and biological interactions that regulate soil health, water resources, and ecosystem sustainability. The subsurface CZ can extend tens to hundreds of metres below the surface and is largely inaccessible, except in happenstance exposures from quarries or road cuts through mountain hillsides. Drilling and subsequent borehole sampling, monitoring, and imaging reveal the importance of the deep subsurface for CZ evolution and function. However, drilling can be labour‐intensive, requires expensive, specialised equipment, and can only be done where the equipment can be deployed, limiting the number and placement of boreholes. Despite these challenges, drilling provides invaluable insights into deep CZ processes. To empower the next generation of CZ scientists to employ drilling and downhole techniques, this review synthesises emerging research objectives and methods commonly used during CZ drilling campaigns over the last 30 years. We focus on three CZ research themes: (1) physical and chemical weathering, (2) water storage and partitioning, and (3) solute, microbial, and gas dynamics. For each theme, we evaluate drilling techniques, sampling strategies, downhole logging approaches, long‐term monitoring, and analytical methods that collectively enable diverse hypothesis‐testing. We conclude by providing a vision for the future of drilling within the CZ, with a focus on novel drilling techniques aimed at recovering saprolitic material as well as borehole designs that can monitor and sample the vadose zone. Additionally, we emphasise that near‐surface geophysics and data‐model integration efforts are needed to expand borehole observations to the landscape scales necessary to advance CZ science and inform ecosystem and water resource management.

  PublisherDOI

• Hydrology, rather than wildfire burn extent, determines post-fire organic and black carbon export from mountain rivers in central coastal California [Dataset]

  HydroShare Resources · 2025-05-29

  datasetOpen access
  PublisherDOI

• Advancing the science of headwater streamflow for global water protection

  Nature Water · 2025-01-02 · 35 citations

  articleOpen access
  PublisherOA PDFDOI

• Shared leadership can promote success in collaborative research networks in ecology

  Functional Ecology · 2025-07-21

  articleOpen accessSenior author

  Abstract While collaborative science is becoming the norm in ecology, many ecologists participating in collaborations are less aware of the body of research that studies the processes by which collaborative teams organize and communicate. Here, we discuss how we successfully used a shared leadership model in the Dry Rivers Research Coordination Network. We discuss how this model promoted our success in different stages of the project, using the Tuckman model of team development: forming, storming, norming, performing and adjourning. Shared leadership in the forming phase helped us recruit a diverse membership from different scientific disciplines. In the storming and norming phases, shared leadership was especially useful in ensuring that all voices were heard in establishing group norms that promoted adhesion among and investment by RCN members. Shared leadership in the performing phase was crucial in providing opportunities for early career members to lead projects, and in the adjourning phase we reflected upon our entire collaboration to identify that shared leadership was crucial to our success, generating the thesis for this commentary. It is our hope that others may find this discussion of our experience in implementing a shared leadership model useful in developing their own fruitful collaborations. Read the free Plain Language Summary for this article on the Journal blog.

  PublisherOA PDFDOI

• Hydrology, rather than wildfire burn extent, determines post-fire organic and black carbon export from mountain rivers in central coastal California [Dataset]

  HydroShare Resources · 2025-03-07

  datasetOpen access
  PublisherDOI

• Climate sensitivity and restoration trajectories: Insights from tidal marsh restoration in Elkhorn Slough, California

  Ecosphere · 2025-07-01 · 1 citations

  articleOpen access

  Abstract Understanding restoration trajectories and their sensitivity to climate is critical for designing effective adaptation strategies for restoration projects. Tidal marsh restoration often involves initial bare earth conditions that may be stressful to colonizing plants, especially on high elevation marsh platforms built to be resilient to sea‐level rise. Under these circumstances, stressors such as soil salinity may increase over time, but can be mitigated by strong rainfall. At Hester Marsh, a large tidal marsh restoration site in Elkhorn Slough, California, we evaluated passive restoration success, tracking colonization by plants whose seeds arrived naturally on tides, and active restoration success, monitoring greenhouse‐grown transplants. Our investigation revealed nonlinear restoration trajectories with high climate sensitivity, at the scale of the entire landscape and of individual plants. We found strong effects of drought on marsh restoration success indicators. Plant colonization rate decreased dramatically over time in the first area to be completed, which experienced more drought conditions following construction. In contrast, it declined more slowly in the second area, which experienced more rainy years following construction. Both passive and active restoration showed strong differences across these areas and across dry and rainy years. Facilitation can sometimes improve conditions for later‐arriving plants, but we found higher mortality of seedlings under existing vegetation than in bare areas. Thus, plant colonization may slow over time both due to increasing abiotic stress and through competition by early colonizers. Our findings lead to recommendations for climate adaptation strategies for tidal marsh restoration. Since we found that the first year following construction appeared to have the least stressful conditions, we recommend managers invest especially heavily in supporting plant colonization during this early window of opportunity. We also found plant size and species affected drought tolerance and recommend larger plant sizes and hardy species be incorporated into active tidal marsh restoration. Furthermore, we recommend planning for phased completion of restoration projects to generate a mosaic of areas with different trajectories and increase the probability that some areas will be completed during optimal climate conditions. We thus illustrate how an understanding of climate sensitivity of restoration trajectories can enhance restoration success.

  PublisherOA PDFDOI

• Greater Rock Moisture Deficits on a Pole‐Facing Hillslope Due To Aspect‐Related Variations in Vegetation Water Use

  Geophysical Research Letters · 2025-09-08 · 1 citations

  articleOpen accessSenior author

  Abstract Water stored in weathered bedrock plays a crucial role in the terrestrial water cycle by influencing vegetation, streamflow, and groundwater recharge. Past studies on the impact of aspect‐driven differences in insolation quantify moisture in shallow soils but largely ignore moisture dynamics in deeper weathered bedrock. Here, we measure moisture dynamics via geophysical surveys and borehole measurements in two opposing hillslopes with similar properties in the seasonally dry central California Coast Range. Despite greater insolation, the grassy equator‐facing slope experienced less and shallower moisture withdrawal during the dry season relative to the pole‐facing slope with oak trees, which experienced greater and deeper moisture withdrawal. Consequently, following the dry season, water content on the grassy equator‐facing slope was higher, which may contribute to aspect‐dependent differences in runoff generation, landslide susceptibility, and drought resilience.

  PublisherOA PDFDOI

• The role of source water chemistry on microbial nitrogen processing in near-surface sediments in coastal salt marsh sediment

  2025-01-01

  articleSenior author
  PublisherDOI

• Neutron Probe Data Processing: Calibration and Conversion to Water Content using Nuclear Magnetic Resonance, and Uncertainty Analysis

  HydroShare Resources · 2025-02-07 · 2 citations

  datasetOpen accessSenior author
  PublisherDOI

Recent grants

• CAREER: Subsurface critical zone architecture controls on hydrologic partitioning across spatial scales

  NSF · $617k · 2021–2027

Frequent coauthors

• Erin Seybold

  University of Kansas

  36 shared

• Samuel C. Zipper

  United States Geological Survey

  21 shared

• Emilio Grande

  21 shared

• Thibault Datry

  Universidade Federal do Ceará

  19 shared

• K. N. Johnson

  University of California, Berkeley

  19 shared

• Maya Montalvo

  University of California, Santa Cruz

  18 shared

• B. L. McGlynn

  Duke University

  18 shared

• John C. Hammond

  18 shared

Labs

• Soil and Environmental Sciences Analysis LabPI

  Staff Timothy Berry, Ph.D. Scientist II, Department of Soil and Environmental Sciences Ph.D. Terrestrial Biochemistry, Purdue UniversityB.Sc. Microbiology, Michigan State University Tim is currently serving as the coordinator for the Soil and Environmental Sciences Analysis Lab and is the primary operator of the FlashSmart and Picarro systems. For his own research, Tim is interested in […]

Education

• Ph.D., Soil Science

  University of Wisconsin-Madison

  1990

• M.S., Soil Science

  University of Wisconsin-Madison

  1986

• B.S., Soil Science

  University of Wisconsin-Madison

  1983