To protect the climate, we need to protect mature and old growth forests

A new study, published today in the peer-reviewed journal Biological Conservation and co-authored by scientists from Woodwell Climate Research Center and Wild Heritage, finds that greater protections of mature and old-growth forests in the United States are critical to meeting global commitments to forestall the climate and biodiversity crisis. The research underscores why safeguarding the nation’s carbon stockpile in older forests needs to be a focus of U.S. policy to reduce emissions from commercial logging and burning of fossil fuels. 

Using a new approach combining remote sensing of forest structure with ground data from the federal Forest Inventory and Analysis (FIA) program, the research team analyzed younger, mature, and old-growth forests across the contiguous U.S., looking at their size and carbon stocks, as well as ownership (public or private) and protection status, to examine how much additional carbon could be protected if stricter regulations were in place to curb commercial timber harvesting. 

According to the study, contiguous U.S. forests currently hold 54.3 billion tonnes of carbon. However, 83% of that carbon stock remains unprotected, revealing the critical role that policy action to prevent increased logging of federal forests can play in promoting ecosystem benefits and enabling U.S. forests to reach their full carbon storage potential. This is especially true for mature and old-growth forests, which provide the greatest climate and biodiversity benefits.

“Mature and old-growth forests are made up of our oldest and typically largest trees, that not only store massive amounts of carbon right now, but can continue to accumulate carbon for centuries if protected. These forests also play an irreplaceable role in maintaining biodiversity, fostering ecosystem resilience, promoting human health, and much more,” said Dr. Rich Birdsey, Senior Scientist at Woodwell Climate and lead author of the study. “As communities everywhere feel the real time consequences of the climate crisis, our policies must reflect the urgent and unparalleled importance of preserving these forests to reduce emissions and bring global temperatures back down.”

With stepped-up protection measures that avoid logging of mature and old-growth forests and large trees, and allow mature forests to develop into old growth over time, researchers found that the total carbon stored in these forests could increase by 10.8 billion tonnes within decades, locking away the equivalent of eight full years of fossil fuel emissions in the United States. 

“Our study points to the urgency of protecting the nation’s best natural climate solution, especially as the current administration begins to ramp up logging on public lands under the President’s executive orders,” said Dr. Dominick A. DellaSala, Chief Scientist at Wild Heritage and study co-author. “This is the worst possible time for backpedaling on forest protections and our international commitments for a safe climate.”

The study can be found here.