Heat Halts Tree Growth in Summer, Clouding Forests’ Climate Role

A multinational study using point dendrometers and 75 years of data finds that many oaks stop producing woody biomass by mid-summer even as photosynthesis continues, meaning forests may absorb less CO2 than climate models assume. Eastern oaks absorbed 36% of their carbon without growth, California oaks 26%, suggesting a decoupling of growth from photosynthesis under hot, dry conditions. The results could prompt revisions to how forests are represented in climate projections and call for broader testing across species and ecosystems.