California’s coast redwoods are adapted to cool coastal conditions averaging around 59°F (15°C), but rising temperatures and heat waves above 100°F (38°C) are disrupting how they feed themselves. A UC Davis study, the first to look at heat effects on redwood photosynthesis, found that the trees slow the process that turns sunlight, water and carbon dioxide into growth fuel. Researchers collected data over three summers in a Mendocino County forest. When air temperatures topped 86°F (30°C), some leaves ran nearly 20°F warmer than the air, suggesting they had closed their stomata to conserve water. Lab tests up to 110°F (43°C) showed photosynthesis was still reduced even with open stomata and plenty of water, meaning extra water may not protect redwoods from heat. The findings raise concerns for redwood forests, particularly in their more vulnerable central, southern and eastern habitats.
Read the full article → https://phys.org/news/2026-09-coast-redwoods-temperatures-spike.html