Biologists at the Institute for Climate and Landscape have identified a gene that switches on only in oaks more than two centuries old - and seems to keep them alive through dry summers.
Working with the owners of six ancient woodlands, the team sampled leaves from 212 oaks of known age over three summers. In trees older than about 220 years, a gene the researchers have nicknamed patience became active whenever soil moisture fell below a threshold, slowing the tree's growth and closing its leaf pores earlier in the day.
Why it matters
Younger trees did not show the same response, which may explain why the oldest oaks in the study came through the 2025 drought with less crown loss than trees a third of their age.
"The old trees are not just survivors," said Dr Ruth Okonjo, who led the study. "They appear to have learned a more cautious way of living." The paper appears this month in Forest Ecology.
