Last updated: September 23, 2025
Article
The Sierra Nevada Monitor: Summer 2025
NPS / Ana Tobio
Welcome, New Staff!
The Sierra Nevada Network has welcomed several new staff over the past year.
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Anne Pfaff – Network Program Manager
Anne Pfaff has returned to the National Park Service in a new role as Network Program Manager for the Sierra Nevada Inventory and Monitoring Network after 25+ years with the US Geological Survey.
Anne started her career with NPS over 30 years ago as an interpretation intern with the Student Conservation Association at Badlands National Park. Her early career path led to a variety of interpretation, resource management, and wilderness jobs at St. Croix National Scenic Riverway and Great Basin National Park, as well as a position as the Refuge Management Specialist with the US Fish and Wildlife Service in the Klamath Basin.
Anne began working in the Sierra Nevada in 1999 as an ecologist and then research coordinator with the USGS Sequoia-Kings Canyon Field Station. While working for USGS, Anne helped design, develop, and execute many field research projects in forest and fire ecology across California, though her focus remained on the Sierras.
Anne has a BS in Biology from Yale College and an MS in Biology from University of Northern Colorado. Her graduate research focused on the behavior and population dynamics of the Gore Range mountain goat herd near Silverthorne, Colorado. Her current areas of interest include landscape conservation and broadscale resource management projects of all kinds. Outside of work, Anne enjoys jogging, reading, hiking, and traveling and visiting with her family.
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Kelly Martin – Physical Scientist
Kelly Martin joined the Sierra Nevada Network in 2024 as their Physical Scientist. She leads water resources monitoring for lakes, rivers, and wetlands in the network’s parks. Kelly holds a bachelor’s degree from Western Washington University and a master's degree in biology from California State University, Fresno. Her master’s project focused on an ecotoxicology study in a remote alpine lake watershed in the Tokopah Basin in Sequoia National Park.
Kelly's previous experience included working at North Cascades, Lake Clark, Yosemite, Sequoia, and Kings Canyon national parks in various ecology and physical science roles. Additionally, Kelly has contributed to the Inventory and Monitoring Division’s lake monitoring programs at the North Coast and Cascades Network and the Sierra Nevada Network.
Outside of work, Kelly enjoys painting, fly fishing, and mountain biking, which allow her to explore the beautiful landscapes she is dedicated to studying and preserving.
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Zoë Klein – Ecologist
Zoë Klein recently began serving as a whitebark pine ecologist for the Sierra Nevada Inventory and Monitoring Network through a partnership with American Forests. In this partnership, her primary focus is developing a conservation plan for whitebark pine that will help guide strategies for conservation, strengthen resilience of healthy forests, and support the long-term stewardship of these ecosystems. While whitebark pine is at the core of this effort, she is also interested in how this work can help to conserve other high-elevation white pines in the Sierra Nevada—western white pine, foxtail pine, and limber pine. Related to this larger conservation effort, she leads a short-term project assessing recent whitebark pine and foxtail pine mortality in the southern Sierra Nevada.
Zoë’s relationship with the Sierra Nevada began with her very first field job as a seasonal biological technician with the network’s monitoring program, hauling a pack full of gear up steep mountain trails to help monitor forests and meadows. Since then, she’s had the privilege of working on a variety of ecology projects, from studying Plantago patagonica (wooly plantain) on the Colorado Plateau during her master’s research, to assessing mortality in whitebark pine and foxtail pine as a field technician with the Sierra Nevada Network, to working as an ecologist in the sagebrush steppe with the US Geological Survey in Boise, Idaho. Every time she left the Sierra for another opportunity, she always knew she would find her way back. The Sierra Nevada has always had Zoë’s heart and working with American Forests to return feels both natural and deeply meaningful to her.
Zoë holds a master's degree in environmental science and policy from Northern Arizona University, where she focused on restoration ecology, functional ecology, and climate change.
Outside of work, she is happiest when she is moving through mountains—backpacking, climbing, or skiing. She also loves long river trips, knitting socks, and reading.
“The Sierra Nevada is a place I keep returning to, both for work and for joy. The opportunity to contribute to conservation in high-elevation ecosystems is deeply meaningful to me, and I’m excited to support the continued stewardship of these landscapes by protecting whitebark pine.”
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George Pharris – Logistics Coordinator
George Pharris is the new Logistics Coordinator for the Sierra Nevada Network this field season. George started work at the end of April and will be with the network through December. Previously, George worked at Yosemite National Park as a Scientists-in-Parks intern studying rockfalls in the park and working with the Yosemite Rock Fall Database, as well as conducting unstable slope assessments along park roads.
George finished an M.S. in Geology at New Mexico Tech in November 2024 focused on the Quaternary slip history of the Alamogordo fault. Outside of work, George loves hiking, playing guitar, and cooking. George is excited about being able to support the important monitoring work done by the Sierra Nevada Network and working with the great staff and crews here.
Monitoring Project Updates
Lakes and Wetlands
NPS / Kelly Martin
Lakes
Far from the beaten path, high mountain lakes of Sierra Nevada national parks are largely pristine, yet not immune to stressors. Changes in the climate, as well as air pollution that falls into lakes, can impact the plants, animals, and other lake biota that depend on lakes for survival.
Since 2008, the lakes crew has been monitoring alpine lakes in three network parks to track water quality conditions and alert parks of any concerning changes. In 2025, the crew sampled 25 different alpine lakes throughout Yosemite, Sequoia, and Kings Canyon national parks. Water chemistry data collected from these lakes will support a long-term monitoring effort investigating water quality trends over time. This monitoring effort has been ongoing for more than 15 years and includes data focused on nutrient inputs and chemistry changes across Sierra Nevada lakes.
What does it take to sample these alpine lakes? A team of four seasonal physical science technicians hike hundreds of miles, gaining thousands of feet in elevation, to access these remote sites. They shoulder heavy backpacks that carry not only their personal gear, but also up to 25 lbs of work equipment, including water samples that need to be brought back and shipped to the lab for analysis. To be able to visit all 25 lakes, the crew splits into teams of two to divide and sample more locations within a given timeframe. This year, the crew traveled to headwater sites in the Merced and Tuolumne watersheds of Yosemite, as well as the Kern, Kings, and Kaweah watersheds of Sequoia and Kings Canyon.
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Wetlands
The lakes crew also conducted a partial sampling of wetland sites throughout the network parks. These fens and wet meadows harbor an unusually rich variety of plant and animal life and are vital for flood control, as well as storing nutrients and sediment. The information collected helps park managers stay up to date on conditions and evaluate potential threats, such as the presence of nonnative invasive plants.
The crew replaced dataloggers that track ground water level and water temperature and took measurements to better understand groundwater dynamics—how groundwater levels fluctuate between seasons and over time—at wetland sites. The team visited 19 well sites this year, including one site at Soda Springs Meadow in Devil's Postpile National Monument.
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Explore the Sierra Nevada Network’s lake monitoring further through these visually rich stories:
Clear Waters story map
Two New Natural Resource Inventories Completed
Over the past year, results from two more natural resource inventories in Sierra Nevada parks have been published:
NPS / Laura Van Vranken
Natural resource inventories are conducted by the Inventory and Assessment Program, which is part of the Inventory and Monitoring Division. These inventories document the presence and distribution of species, including vegetation species and communities, and geologic and soil resources. Inventory projects provide credible science to assist park managers with planning, management, and stewardship activities.
NPS / Tory Ash
There are currently 10 active inventory projects in Sierra Nevada Network parks and three recently completed projects. Once each year, park or network staff submit proposals for review and selection by a regional panel.
Most inventory projects are completed in partnership with cooperators. Each inventory produces a report and dataset(s), as well as any other products specifically needed by the park.
Following is a table summarizing the status of inventories in Sierra Nevada Network parks through fiscal year 2025:
Status of inventory projects in Sierra Nevada parks
|
Inventory project (short name) |
Status* |
|
SEKI sequoia groves |
|
|
YOSE white pine blister rust |
|
|
DEPO owls and bats |
|
|
SEKI KNP mixed conifer |
Report in review |
|
SEKI YOSE fisher habitat |
Report in review |
|
SEKI red fox |
In progress |
|
SEKI fisher |
In progress |
|
SEKI YOSE yellow-legged frog |
In progress |
|
SEKI spotted owl |
In progress |
|
YOSE river otter |
In progress |
|
YOSE great grey owl prey |
In progress |
|
SEKI Northwestern pond turtle |
In progress |
|
SIEN NCCN whitebark pine distribution |
In progress |
Research Updates
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White Pine Mortality Project
This summer, we collected the final year of data for the white pine mortality study at 35 plots in Sequoia and Kings Canyon National Parks and Yosemite National Park, measuring approximately 2000 tree stems. This adds to the 2023 dataset that we are now analyzing to better understand the extent and causes of mortality in high-elevation white pine—specifically whitebark pine and foxtail pine. The information is also helping us validate an existing remote sensing tool developed by researchers at UC Davis and the US Forest Service that estimates canopy loss across various ecosystems.What We’re Learning from a Decade of High-Elevation Forest Monitoring
NPS / A. Tobio
Perched high on mountain slopes, hardy pine trees have long anchored the thin soils and windswept landscape of the southern Sierra Nevada subalpine. Today, these landscapes face mounting stress, and new research is analyzing 10 years of monitoring data to assess how high-elevation white pines are responding.
Whitebark pine and foxtail pine—both “white” pines—play foundational roles at high elevation in the southern Sierra Nevada. Their roots stabilize the soil, shade from their branches prolongs snowmelt and thus downstream flow, and nutritious seeds from the whitebark pine feed wildlife. Yet these species face growing threats from white pine blister rust, drought, and bark beetles. For example, severe declines in whitebark pine across its northern range led to its listing as a federally threatened species in 2022. This threat to the larger population underscores a vital management question: is the southern Sierra a refuge for whitebark pine, or are similar warning signs emerging here too?
Since 2011, the Sierra Nevada Network has monitored these high-elevation white pine forests, measuring characteristics such as tree growth, crown health, and evidence of damage. The network completed a third cycle of plot measurements in 2022. This rich dataset provides a powerful opportunity to track forest change across space and time. With the field crew temporarily on pause, the network is using the break strategically to conduct a deep dive into the data. Graduate student Erika Blomdahl of Utah State University is leading an analysis to examine forest condition over time and the occurrence of forest stressors such as bark beetles and blister rust.
NPS / Erika Blomdahl
Although results are still preliminary, several trends are beginning to take shape. Signs of resilience are evident: slow but positive net growth, new trees are being recruited into the population, and overall forest structure has remained relatively stable across the monitoring record. At the same time, warning signs are also emerging. Tree mortality spiked in 2021 and 2022, largely from bark beetle activity, and observations of white pine blister rust are slowly increasing. Further analysis will help clarify the scope and significance of these patterns.
We are excited to share that the National Park Service has recently expanded support for this research. The next phase will dig further into the environmental drivers of tree mortality, place Sierra Nevada whitebark pine in the context of rangewide trends, and help to prepare the monitoring program for a strong re-launch in 2026.
Recent Publications
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Denn M., M. Darby, D. Weeks, J. Wagner, K. Nydick, J. Nesmith, A. Demetry, and S. Haultain. 2025. Wet meadows at Sequoia and Kings Canyon National Parks in a changing climate: A resist–accept–direct (RAD) management application study (revised 2025). Science Report. NPS/SR—2025/253. National Park Service. Fort Collins, Colorado. https://doi.org/10.36967/2309075
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Henderson T. 2025. Sequoia and Kings Canyon National Parks: Geologic and Soil Resources Inventory Summary. National Park Service. https://irma.nps.gov/DataStore/Reference/Profile/2307987
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Mohr M.D., J.E. Cribbs, A. Latimer, and J. Dudney. 2025. Inventory of white pine blister rust, fire, and bark beetles in sugar pine at Yosemite National Park. Science Report. NPS/SR—2025/247. National Park Service. Fort Collins, Colorado. https://doi.org/10.36967/2308879
Data package associated with the Mohr (et al.) report:
Dudney J and Others. Blister Rust in Sugar Pine Inventory at Yosemite National Park. 2023. National Park Service. https://irma.nps.gov/DataStore/Reference/Profile/2310957
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SIEN and Others. 2025. Sierra Nevada Network Landbird Monitoring Data Package, 2011-2024. National Park Service. Fort Collins CO. https://doi.org/10.57830/2307334
More Information
Sierra Nevada Inventory & Monitoring Network
National Park Service Inventory & Monitoring Division
Newsletter Editor: Sonya Daw
Sierra Nevada Inventory & Monitoring Network