There has been an ongoing debate about the viability of tree planting and forest restoration to fight climate change. But this debate — focused on sequestering more carbon — has neglected the many non-climate benefits of better forest management, such as clean water, wildlife conservation, and economic support for rural communities.
Trees as a climate solution are not a new idea. The physicist Freeman Dyson proposed the idea in 1977, and Al Gore noted it in his documentary An Inconvenient Truth almost 15 years ago. But the concept has recently emerged as a rare point of bipartisan agreement around climate solutions. In fact, Republicans have made it a centerpiece of their current climate agenda with McCarthy’s recent Trillion Trees legislation, and Democrats have highlighted the concept in many of their recent climate plans.
However, the carbon benefits of such proposals are fairly modest — due to challenges associated with carbon accounting, land use conflict, and tree planting in areas that were not previously forested (dark tree cover in areas that were previously more reflective can actually increase warming, a phenomenon called the albedo effect). At best, without displacing agricultural land, tree restoration could remove up to 540 MtCO2 annually, equivalent to only 11 percent of energy emissions in 2019. Therefore, planting trees is best seen as a compliment for, rather than a substitute for, emissions mitigation.
But while tree planting has its limitations, improved forest management policy is still sorely needed in the US. Such policy should recognize that the health of forests requires restoring natural fire regimes and encouraging smarter logging practices, two things that might seem antithetical to a singular goal of emissions reductions but support forests’ ability to both balance legitimate competing priorities and store sequester carbon over the long term.
Strengthening Forest Resilience by Restoring Natural Fire Regimes
Healthy forests offer a variety of “ecosystem services,” including clean water, carbon storage, and wildlife habitat. Smart forest management can increase forest resilience to climate change impacts and can help maintain these services in a changing world.
Today, forests in the US must contend with a multitude of climate-driven stressors, which may fundamentally compromise forest carbon sinks in the 21st century and severely undermine our ability to use forest management as a successful climate solution. Fire, drought, harmful insects, and disease are the primary risks, which will increasingly amplify each other as climate change worsens.
We are already seeing these climate-driven impacts on US forests. The number of Western forest fires has been increasing, especially those that grow to more than 100,000 acres. These massive fires can burn the topsoil and underlying seed banks, hampering a forest’s ability to naturally regenerate. Drought is also a growing concern. The 2001-2015 California drought killed an estimated 140 million trees and changed the state's forests from a net sink to a net carbon emitter. Shorter and milder winters are also enabling the spread of bark beetles, which can quickly decimate drought weakened forests. Overall, the average annual mortality rates of forests have increased nationwide over the last decade (mortality rates in the Rocky Mountains have doubled in that same timeframe). Changes in tree species composition and distribution are also being observed. For example, red maple, a species that thrives on disturbed land, is now the most numerous tree in the conterminous United States.
Communities across the US depend on healthy forests for access to clean water and protection from catastrophic forest fires. Improved forest management can help maintain healthy watersheds by increasing water flow, decreasing flood risks, and keeping water temperatures cool for vulnerable fish species during hot summer months. And, preventing catastrophic wildfires can help protect these watersheds. When megafires destroy all vegetation across the landscape and limit the ability of forests to regenerate, the soil is unable to absorb and filter rainfall, leading to massive runoff events, erosion, and flooding that would otherwise be more limited.
Compromised forest resilience is also a threat to wildlife conservation. Even fire-adapted ecosystems can suffer when catastrophic fires burn at such intensity and frequency that they cannot recover.
So, how to improve forest resilience in the era of climate change? Start by fighting fire with fire. In the past, forest managers have made efforts to suppress all fires, which has resulted in dangerously high fuel loads. Over the last 20 years, the use of prescribed fire increased about 5 percent each year, but nearly all of that increase (98 percent) was in the Southeast US — not in western forests where overly dense vegetation and megafires are most prevalent. While prescribed fire can lead to more emissions in the short term, this practice can reduce the risk of the truly massive fires we have seen in recent years, and their associated emissions.
Mechanical treatments are another valuable tool. Thinning overly dense stands can prevent “fuel ladders” which would otherwise result in a type of crown fires that truly decimate forests.
By implementing mechanical thinning, forest managers can reduce the risk of megafires and ensure watersheds remain resilient in a changing climate. Such practices can also create outdoor jobs in a time when the economy is in a downturn and may be more feasible near developed areas where prescribed fires could concern local residents.
There are other promising restoration practices — including planting genetically diverse and resistant trees that are more resilient to insect infestations, disease, and drought — but additional federal research would be necessary to scale them up responsibly.
It is important to note that forest management policy that is overly focused on carbon sequestration could result in ecosystem conversion and undercut efforts to preserve healthy watersheds and protect biodiversity. A recent study examined subsidy driven plantation expansion in Chile between 1986 and 2011, and the resulting carbon and biodiversity impacts. Focusing tree planting efforts on commercially valuable species, as opposed to restoring native forests, resulted in plantation forest area doubling between 1986 and 2011, while native forests shrunk by 13 percent. While the program was successful from an economic perspective (forestry and tree products in Chile accounted for exports of $2.3 billion in 2019), it was a failure from a biodiversity and carbon perspective. Because plantation forests often consisted of only one or two valuable tree species, biodiversity declined in Chile. Further, while “forested area” expanded by more than 100 percent between 1986 and 2011, the carbon stored in vegetation increased by just 1.98 percent — offering poor results.
Forest management must take a balanced approach to maintaining ecosystem services, and carbon sequestration alone should not take precedence over other benefits. Such a holistic approach to management is expensive — estimates for restoration efforts range from $600-1500 per acre. However, when such costs are held up against the cost of catastrophic fires, floods, and other risks associated with poorly maintained forests (last year’s Camp Fire in northern California caused nearly $13 billion in damages) they seem fairly cost-effective.
Supporting Rural Economies Through More Sustainable Logging
Forests offer another valuable commodity beyond the ecosystem services discussed above — timber. Granted, logging has climate impacts — altogether logging in the US emits far more carbon than forest fires. But the timber industry is integral to the American economy, and to rural economies in particular. The industry employs about one million workers and accounts for approximately 6 percent of the total US manufacturing GDP, similar to the automotive and plastics industry. And while the US only has 5 percent of the Earth’s population it consumes an estimated 28 percent of the Earth’s industrial wood products, and a staggering 96 percent comes from domestic supplies.
Because the US timber industry is such a critical component of rural economies, simply halting extraction via regulatory measures is unlikely to prove a winning emissions reduction strategy. While stricter environmental laws have played a role in limiting harvests on federal lands, they have done little to halt overall timber production, merely increasing incentives to shift production to private lands. National Forests accounted for 35 percent of reserved forest land area nationwide, but tree removals for products, fire management, and land-use changes on national forests consumed only 0.2 percent of standing volume on average, annually. In contrast, close to 90 percent of wood harvested comes from private lands.
Instead, a better strategy would be to overhaul harvest practices on federal lands (and encourage better practices on private lands). Current logging practices can be vastly improved to minimize negative environmental impacts, and policymakers have an opportunity to make the US a world leader in sustainable forest management.
The surprising fact is that even though logging was reduced in national forests, they are not thriving in its absence. Despite the low volume of wood extracted from national forests, average annual net growth (calculated as gross growth minus mortality) declined while average annual mortality nearly doubled from 2006-2016. These patterns reflect aging forests and combinations of wildfire, drought, and insect infestations.
Policymakers should incorporate sustainable timber harvesting into tree planting policy proposals — incentivizing solutions that don't simply shift demand from national forests to private lands, but instead re-make the timber industry so that it supports ecological sustainability and helps improve long term forest health. Examples of better practices include those that require an increase in harvest rotation length, incorporate reforestation practices that speed the recovery of degraded lands, and ensure the exclusion of harvest in old-growth forests.
Environmental, economic, and social challenges are interconnected, and solutions that benefit multiple aspects of these challenges, even if they don’t directly benefit climate change, are critical. Forest health is declining, and forest managers do not have adequate support to address the full scope of today’s challenges. There is a unique opportunity to harness public support for tree planting and forest restoration to ensure US forest management policy reflects 21st century needs.