A six-year experiment found elevated carbon dioxide helps oak trees secure more nitrogen, boosting forest growth and carbon storage.
A ring of pipes has blown carbon dioxide over a stand of 180-year-old English oaks in Staffordshire, England, since 2017. The gas runs in daylight only, from budburst in April to leaf fall in November.
Oaks inside those rings breathe air at 573 parts... [6115 chars]