By Andrew Avitt, Oct. 13, 2022
Overstock Forests in the Pacific Southwest Region from Pacific Southwest Region on Vimeo.
Overstocked forests affect forest health by making them more prone to disease and invasive species, more susceptible to drought and wildfire. (USDA Forest Service photo)
To an untrained eye, dense forests across the country might seem in good health and, well, natural. But what many foresters will tell you is these forests are overstocked, with too many trees growing far too close together. This overgrowth affects forest health and the ability to withstand drought, pests, diseases and wildfire.
“Overstocked forests — or dense forests with too many trees — often affect the overall health of the forest,” said Jeff Jones, a vegetation manager on the Six Rivers National Forest. “Trees must compete for space and resources such as sunshine, nutrients and water, and the ongoing drought in California only adds to that stress.”
One main contributing factor to overstocked forests across the country is years of fire exclusion on landscapes that had adapted to naturally occurring wildfire, said Jones. A recent study from the Forest Service’s Pacific Southwest Research Station looked at data on forest conditions between 1911 and 2011, noting, “tree densities on average increased six- to seven-fold while average tree size was reduced by 50 percent.” This means more trees are competing for fewer resources, making them more susceptible to invasive species and disease.
These environmental threats differ across the state and the country depending on climate, elevation and various ecosystems. For example, a non-native disease known as Sudden Oak Death targets coastal forests like the Six Rivers National Forest.
Sudden Oak Death, a water mold pathogen, thrives in wet environments and spreads by warm, spring rains. So, in an overstocked forest with disrupted wind flow across the landscape, fungi like Sudden Oak Death can thrive, compared to a cleared forest with more airflow to stifle the disease.
While threats to trees in forests across the state vary, the result of overstocked forests is much the same — stressed and dying trees.
“These threats that otherwise would have had a harder time affecting a healthy tree are now able to take hold,” said Jones. “The result tends to be an unhealthy forest and makes for extreme wildfire conditions.” 
The wood products industry supports local economies, creates jobs, and supports forest health by returning landscapes to their natural densities. (USDA Forest Service photo)
A Forest Reset
Returning fire to the landscape is one important tool that helps improve forest health – it’s how these forests used to evolve naturally under the stewardship of indigenous people. However, using controlled fire to return forests to historical conditions depends on the weather, drought history, and prior reductions in tree densities and fuel loading.
On the Six Rivers National Forest, land managers and partners are using several different methods to restore forests to their historical density.
Larry Swan, a Wood & Biomass Utilization program leader with the Forest Service, has worked with hundreds of businesses and nonprofits over the last 30 years. His work focuses on restoring healthy forests by removing excess logs and biomass with the help of valued partners.
“We can’t maintain healthy forests without thriving and sustainable forest businesses,” said Swan. “These businesses are vital to help reduce tree densities where they are creating unhealthy conditions. They also create a wealth of economic opportunities that ripple through rural communities and create many local jobs.”
These jobs range from foresters and ecologists, scientists overseeing the environmental review processes, tree nursery workers, and heavy equipment operators for roads, infrastructure and excess material removal, truckers, sawmill workers, and other forestry and wood-processing professions.
“When we talk about sustainable industry, we are talking about businesses that are competitive, environmentally sustainable, and profitable in the long run,” said Swan. “These types of businesses are essential to helping land managers meet healthy forest objectives on private and public lands.”
The Forest Service hosts programs to help businesses and nonprofits participate in land management activities, such as the Wood Innovation and Community Wood competitive grant programs.
“A long-standing challenge for any forest-based business is what to do with logs and other debris that cannot be processed by existing sawmills and other processing plants,” said Christy Prescott, a social scientist with the Forest Service’s Enterprise Program. “The market value for those materials remains low, so we are focused on creating a market-driven model that increases demand and revenue, to offset treatment costs for forest health projects.”
In an overstocked forest, trees can become stressed or die due to less resources, water, sunshine, and nutrients from the soil and often exacerbated during times of drought. (USDA Forest Service photo)
Potential Market Solutions
An area of wood products being explored by innovators is mass timber. Mass timber uses state-of-the-art technology to glue, nail or dowel smaller wood materials together in layers. The results are large structural panels, posts and beams that would compete with more traditional building materials such as steel or concrete.
Mass timber is widely used in Europe as a green, non-toxic construction material. Though the industry is still up-and-coming in the United States, use of mass timber could support forest health and create affordable housing.
Mass timber is just one of many innovations being explored by the Forest Service through the Innovative Finance for National Forests Grant Program and CalForest WRX Alliance, a group of partners in Northwest California.
“We are seeking to help communities become more resilient and sustainable in terms of reducing wildfire risk, while also creating economic opportunities that will support job creation and local communities,” said Prescott.
The Forest Service continues to work with partners to return forests to their historical densities and better health using a variety of methods.
“There isn’t one solution that is going to create conditions for a healthy forest, to make them more resilient to invasive species, disease, drought, and wildfire,” said Swan.
Forest health is going to depend on a variety of land treatments like prescribed fire, pile burning, and mechanical thinning as well as partners — including state and local government, tribal, and large and small businesses — who are key to improving forest health and stimulating more robust rural economies.
The CalForest WRX Alliance is comprised of many partners in Northwest California including, the County of Humboldt’s Economic Development Division, Cal Poly, Humboldt Green Diamond Resource Company, and Western Klamath Restoration Partnership.
For more information on the Innovative Finance for National Forests Grant Program and innovative approaches being explored in California and across the country, please visit the National Forest Foundation.