They are the ancient giants of America – towering trunks of sequoias or beech or ash that started to sprout in some cases before the age of the Roman empire, with the few survivors of a frenzy of settler logging now appreciated as crucial allies in an era of climate and biodiversity crises.

Joe Biden has vowed to protect these “cherished” remnants of old growth forest, as well as the next generation of mature forests, directing his government to draw up new plans to conserve the ecological powerhouses that enable US forests to soak up about 10% of the country’s carbon emissions, as well as provide a vital crucible for clean water and wildlife.

Yet, the US Forest Service has not included mature trees in this new plan, which also includes loopholes conservationists say allow ongoing felling of trees that are hundreds of years old. The Forest Service, responsible for 154 national forests and nearly 25m acres (10m hectares) of old growth trees in the US, has also largely declined to conduct required reviews of multiple logging projects amid a stampede of tree cutting that threatens the oldest, richest trees before any new curtailments are imposed.

“The largest logging projects I’ve ever seen are targeting the last, best remaining old growth trees left in the country,” said Chad Hanson, a forest ecologist and co-founder of the John Muir Project.