Protecting big trees for wildlife also benefits climate

Study highlights the importance of protecting mature and old growth forest

Peer-Reviewed Publication

CONSERVATION BIOLOGY INSTITUTE

Earth Day: April 22, 2023
 David Mildrexler, Ph.D., davidm@eorlegacylands.org
Bev Law, Ph.D., bev.e.law@gmail.com
Bill Moomaw, Ph.D., William.Moomaw@tufts.edu

Large trees offer major solutions to the climate and biodiversity crisis that are needed now. As
President Biden calls for protecting mature and old growth trees on Federal lands, the study
describes synergies between protecting these disproportionately valuable large trees and forest
resilience goals, providing common solutions for these urgent challenges.
An earlier analysis found that large trees protected by the “21-inch rule” account for just 3% of total
stems in the affected forests but hold 42% of the total aboveground carbon.
Rather than continuing to protect these inherited carbon and biodiversity treasures, the United States
Forest Service recently relaxed the 21-inch rule opening the door to large tree logging across
millions of acres of National Forest lands east of the Cascades Crest in Oregon and Washington.
The justification for weakening the screens- competition between large trees, is not supported by the
new analysis.

Large-scale cutting of even some of the existing big trees would eliminate these carbon stores while
releasing vast amounts of carbon dioxide to the atmosphere when we need to have greater
sequestration by natural systems to stabilize Earth’s climate.
Interest is growing in policy opportunities that align biodiversity conservation and recovery with
climate change mitigation and adaptation priorities. The authors conclude that “21-inch rule”
provides an excellent example of such a policy initiated for wildlife and habitat protection that has
also provided significant climate mitigation values across extensive forests of the PNW Region.
“These are public lands that are providing a natural climate solution and performing multiple
additional services at no cost. We suggest policy to keep existing forest carbon stores out of the
atmosphere and accumulate additional amounts while protecting habitat and biodiversity.” David
Mildrexler

“There is no action required from us but to leave these large trees standing so they can continue to
store and accumulate carbon for climate mitigation and provide critical habitat.” Bev Law

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JOURNAL

Conservation Science and Practice

DOI

10.1111/csp2.12944 

METHOD OF RESEARCH

Meta-analysis

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Protect large trees for climate mitigation, biodiversity, and forest resilience