Redwoods face climate threats

The tallest trees on Earth, redwoods, are in danger due to climate change, according to a study published in September in the journal JGR Biogeosciences. Scientists warn that rising temperatures are disrupting the trees' ability to perform photosynthesis, which could threaten their future survival.

Ancient trees retreat to coastal areas

Redwoods are among the oldest tree species, appearing over 20 million years ago and once spreading across the Northern Hemisphere. However, climate changes pushed them to retreat to the foggy coasts of northern California and southern Oregon, where they now grow.

Study tracks redwood leaf physiology

A two-year study, from July 2022 to October 2024, measured the physiological responses of redwood leaves. It found that during heat stress, the trees' ability to perform photosynthesis decreases significantly, and their capacity to cool their leaves also diminishes.

Leaf temperature rises with heat

When temperatures reach or exceed 30°C, redwood leaves can become up to 11°C warmer. The trees struggle to cool down, which affects their ability to carry out essential biological processes.

Stomata help trees breathe and cool

Stomata, small pores on the surface of leaves, allow plants to absorb carbon dioxide and release oxygen. However, with rising temperatures, these pores open more to transpire, which cools the leaves. When fog layers disappear, the stomata close to conserve water, causing leaf temperatures to rise.

Lab experiments show heat impact

Laboratory experiments confirmed that even when leaves are well-hydrated and stomata remain open, photosynthesis still declines under high temperatures, indicating a direct impact of heat on the trees' biological functions.

Researcher highlights study's importance

Lily Klinek, lead author of the study and a researcher at the University of California, Davis, emphasized the findings show a significant impact of heat on redwood physiology. She noted the study is an important step toward protecting these ecosystems.

Future temperature rise threatens redwoods

Reports from the Scripps Oceanography Institute and the United States Forest Service predict that coastal temperatures could rise by 6.8°C by the end of the century. This increase would make it impossible for redwoods to adapt to climate change.

Redwoods may signal broader forest vulnerability

Researchers suggest that the vulnerability observed in redwoods might be part of a larger trend affecting temperate forests worldwide. They argue that understanding thermal thresholds is crucial for assessing climate resilience in forest ecosystems.