UC Davis Study Linked Heat to Redwood Decline
Researchers found that high temperatures forced California coast redwoods to slow essential photosynthesis.
Updated on Sept. 28, 2026 in Botany
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A 2024 study from the University of California Davis revealed that coast redwoods in Mendocino County experience reduced photosynthesis during heat stress. The trees limit their physiological processes to prevent water loss as temperatures rise.
Why it matters
High heat triggers redwoods to close their stomata, which protects them from immediate desiccation but forces them to slow the breathing and eating processes necessary for growth. This mechanism highlights the vulnerability of these ecosystems as coastal fog, their primary water source, diminishes.
Researchers measured leaf temperatures nearly 20 degrees higher than the surrounding air during extreme stress. Laboratory tests further confirmed physiological suppression at temperatures ranging up to 110 degrees Fahrenheit.
The players
University of California Davis
This is a public land-grant research university that maintains extensive agricultural and environmental science programs.
National Science Foundation
This is a United States government agency that supports fundamental research and education in all the non-medical fields of science and engineering.
California Forestry and Fire Protection
This state department is responsible for fire protection and resource management on thousands of acres of California wildlands.
The details
To manage extreme heat, coast redwoods utilize their stomata to release moisture through evapotranspiration, but they must close these pores when temperatures exceed 86 degrees to prevent lethal water loss. This defense mechanism causes the trees to overheat and significantly reduce the metabolic processes that fuel their development.
Timeline
Researchers conducted field measurements in Mendocino County during the summer of 2022.
Follow-up field measurements were taken throughout the summer of 2024.
The Big Picture
This study follows the peer-reviewed methodologies established by the JGR Biogeosciences environmental monitoring framework to quantify physiological stress in changing climates. The findings update the legacy understanding of forest resilience by identifying specific temperature thresholds where basic metabolic functions begin to fail.
The study results will assist state land managers in identifying which forest ranges are at highest risk of heat-related mortality. This data is critical for prioritizing conservation efforts and water management strategies for California redwoods in the coming decades.
The takeaway
Redwoods have evolved to thrive in cool, consistent environments, making them particularly sensitive to the loss of coastal fog. Maintaining forest health may require deeper focus on regional temperature stability and water conservation in areas where the climate is shifting toward heat extremes.
Further reading
For more on plant physiology and environmental impacts, explore the Botany section.
Source note: This article includes information reported by YubaNet.
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