Resource Science: A new category of forests – Old growth

You probably know about federal government initiatives and regulations to control land and water such as waters of the U.S. (WOTUS) and the Endangered Species Act (ESA). Now, there’s old growth forests. On April 22, President Joe Biden signed the Executive Order on Strengthening the Nation’s Forests, Communities and Local Economies.

Included in this order is the policy: “To pursue science-based, sustainable forest and land management; conserve America’s mature and old-growth forests on Federal lands; invest in forest health and restoration; and deploy climate-smart forestry practices … to improve the resilience of our lands, waters, wildlife, and communities in the face of … climate impacts.”

The U.S. Forest Service (USFS) was tasked with defining and inventorying old growth and mature forests on federal lands, primarily USFS and Bureau of Land Management (BLM) lands, and published a report in 2023. They found that there are more than 32 million acres of old growth, including 24 million acres on USFS land and 8 million acres on BLM land.

The USFS foresters writing the report realized that old growth needed to be defined differently for different regions, forest types and tree species. They produced an empirical report in which they note that defining old growth forests has been done from the 1940s through the 1990s, and the definitions in their 2023 report are considered working definitions that will be refined over time with new information. An example of an old growth definition for the USFS Northern Region 1 in northern Idaho is included in the accompanying table.

This is only part of the old growth forest definition for the northern Idaho zone. There are other definitions for all of the USFS regions and forest types in the 2023 USFS report. Also, mature forests noted in the executive order are defined as the successional stage just prior to the old growth stage. Why is the executive order on old growth forests important?

The 2023 USFS report explains: “Executive Order 14072 is about fostering resilience in our forests in an era of rapidly changing climate … it’s about the critical role our forests play in slowing the pace of climate change and conserving biodiversity; … the importance of old-growth and mature forests on Federal lands for … their role in contributing to nature-based climate solutions by storing large amounts of carbon. These forests are also at risk from climate-related stressors and disturbances…”

There’s lots of key words in this quote, but the focus is old growth as a “nature-based climate solution.” Maybe, but all forests, not only old growth, capture carbon from the atmosphere. For example, others note the importance of forests for sequestering carbon and estimate that forest land in the U.S. captures 11% of the U.S. greenhouse gas emissions in tree growth, dead organic matter and wood products.

From my experience, I suspect the proponents of preserving old growth are acknowledging forests’ potential to sequester carbon but have a secondary intent of preventing timber harvest. Consider that environmentalists have opposed timber harvest for decades, and now old growth is designated as important to climate change.

However, it is obvious that timber harvest with regeneration of trees and sequestration of carbon in wood products is also legitimate forest management, which I’ve written about before (WLJ Nov. 21, 2022). It is also obvious that preventing forest fires is a major way to prevent greenhouse gases from entering the atmosphere. I believe that common sense forest management with timber harvest and fire prevention should be emphasized rather than focus on old growth with regard to carbon and climate change. Letting old growth burn will not help with climate change.

There is another consideration I recognize from my experience with environmentalist agendas. Recall the wide scope of WOTUS attempting to regulate all land with any water on it, and recall the ESA including subspecies and distinct population segments in the species definition which allows the listing of a single wildlife population. Old growth forests and mature forests (noted in the executive order) are now categories with special, protected status regarding carbon and climate change.

Although there is uncertainty and debate about climate change, recognizing older forest stands as valuable is a legitimate forest management objective. But to really help with climate change, active forest management with timber harvest and fire prevention is needed. This will sequester carbon and greenhouse gases in wood products and regenerating trees. Currently, forests sequester 11% of the U.S. greenhouse gas emissions.

This could be substantially increased if more timber is harvested and sequestered in wood products, forest trees are regenerated and forest fires prevented. The science on the topic of what forest management is most effective at sequestering carbon is complex, but it seems obvious that preventing forests from burning should be a primary objective in this regard. — Dr. Matthew Cronin, WLJ columnist

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