sustainable forestry

Passive Forests?

by

by Brent Sohngen (Sohngen.1@osu.edu)

I’ve been puzzling over the paper by Allen et al. (2025) since it came out earlier this year. On land use and forestry, the authors seemingly dump all human agency into the “passive sink”, that is, nature-based carbon storage obtained without humans. Specific forest-based mitigation can be used to lower net emissions in the land-using sectors, but that’s about it.

The passive forest carbon sink, of course, has been an existential threat to climate progress from the beginning. Many will recall when Al Gore arrived at COP 3 in Kyoto with a plan to get the US below 1990 emission levels by using credits generated in part by passive forests. This plan was met with skepticism.

However, from Kyoto we got the Managed Land Proxy (MLP), which is a simple tool developed by the Intergovernmental Panel on Climate Change (IPCC) that allows countries to include carbon from land use in their UN Framework Convention on Climate Change (UNFCCC) accounts. Countries declare which forests they are going to measure, and they include that carbon in their accounts.

Carbon derived in these measured forests can be added with energy emissions and included in the net emission calculations of any country.

The “proxy” part was included in the name because what happens in forests is not always a function of direct human action. Planting and cutting trees are quite obviously anthropogenic, but bug infestations, forest fires, or CO2 fertilization? These may only indirectly be linked to humans. For simplicity, under the MLP, any carbon changes are assumed to result from human agency.

Consider forest fires. In the US, most forest fires are caused by human ambivalence and there is a strong argument that our history of forest management, or lack thereof, makes fires worse. So it seems reasonable that fires be included with other human drivers in the US.

In Canada, things are different. Way back in the late 90s and early 00s, some of Canada’s forests were delivering net sequestration, so government designated land storing carbon as part of the MLP. Almost immediately, things turned south as bugs swept through their forests, and then they burned. Canada responded by recognizing this nuance and adjusting their carbon accounting.

A bigger issue than forest fires, however, is the growing global carbon sink due to CO2 fertilization and climate change. Allen et al. argue that most of this carbon would be taken up without human intervention – that is, it’s happening passively.

More importantly, Allen et al. claim that because this carbon removal will happen with or without direct human intervention, including it as part of country or corporate net zero commitments will increase long-run carbon concentrations.

The physics is indisputable, but the policy is suspect. Where is the human agency?

Most forests have been influenced directly by human actions. A report by scientists at Winrock International, for instance, found that only 16.6% of the world’s current forests could be classified as “stable”, meaning “those not already disturbed nor facing predictable near-future risks of anthropogenic disturbance” (see Funk et al., 2019).

Of course, with all that human disturbance out there – especially tree harvesting and deforestation – one could argue that it really is just pure dumb luck that forests are sequestering anything.

Is it really just luck?

Predictions from some of the original assessments of how people adapt to climate change suggest that forest carbon fluxes are not all just a function of happenstance. Figure 1 presents a comparison in a 1998 journal article predicting the natural response to a doubled CO2 experiment with a model that predicted how humans would respond to the climatic and ecological perturbations, including increased forest dieback through fires, shifts in growth rates due to changes in CO2 concentration as well as temperature and precipitation, and shifts in the distribution of where forest species could regenerate.

Figure 1: US forest carbon flux prediction with climate change using predicted climate impacts from a doubled CO2 experiment on forests from the VEMAP project integrated into an economic model of forest management, derived from Sohngen et al. (1998). Positive values in this figure represent a removal from the atmosphere, while negative values represent an emission.

The experiment in Figure 1 was implemented assuming a linear adjustment over 70 years, which over-estimates the speed of the shift in climate. The economic model also over-estimates the portion of land that will be managed intensively or somewhat intensively. The results are nonetheless instructive, illustrating how simple adaptive mechanisms of harvesting forests early before they burn, salvaging what cannot be prevented from burning, replanting species better adapted to survive in the future can accomplish, and simply managing forests for increased growth due to fertilization and climate.

The takeaway: humans won’t sit idly by as forests are influenced by climate change, at least in places where they have agency and can manage their forests.

Whether those impacts are bugs, fires, or increased growth due to CO2 fertilization, we are now 40 to 50 years into this experiment on our atmosphere, and the evidence is clear that foresters are responding to climate drivers (Davis et al., 2022).

Instead of being passive, foresters are actively engaged in adaptation. Assuming all flux, or even just the emissions from harvesting, is passive is a mistake.

The US has a large forest carbon sink. The suggestion of Allen et al. is that this carbon is accumulating without our help. Using data collected by the US Forest Service, however, it is clear that the accumulation of carbon has strengthened on private land while it has dissipated on public land (Figure 2). Over the same time period forest management has all but disappeared on federal lands in the US.

In a world with climate change, it is increasingly difficult to assume away human adaptation to the forces of change affecting forests. Although it may be convenient to assume that all of the observed carbon accumulation in forests lacks a human origin, that’s clearly not the case.

Figure 2: US forest CO2 flux on public and private land. Data obtained from Domke et al. (2022)

Where will the trees come from? How tariffs and new policies mean big changes on federal forests.

by



by Brent Sohngen (sohngen.1@osu.edu)

In this post:

  • An assessment of the President’s recent executive order promoting timber harvests from federal lands to replace the 1.5 to 2 billion ft3 we import from Canada if tariffs reduce those flows.
  • Federal harvests provided 2 billion ft3 per year, 15-20% of U.S. timber, until the early 1990s, but were reduced for environmental reasons. Now they provide 0.3 billion ft3 per year.
  • Stocks have since grown significantly on these left-alone lands, and about 100 billion ft3 is reasonably available for harvest in the next few decades.
  • Harvesting levels of 0.9 to 1.3 billion ft3 per year would equal current growth and fire losses on these hectares and would promote thinned and younger stands that would be more resilient in the future.
  • There are environmental risks to building such a program that should be carefully weighed.

Now we know how the Trump administration plans to combat the effect of higher tariffs on wood prices: Harvesting more timber from federal forestlands, predominately in the western U.S. This approach would reverse thirty years of modest harvests from these forests, which began in the 1990s when the Endangered Species Act was invoked to slow down timber production in old growth forests that housed the Northern Spotted Owl (Strix occidentalis caurina).

Throughout their history, federal forests have been a punching bag, swinging back and forth between periods of protection and intensive logging as environmentalists and loggers duked it out in the court of public opinion and in front of judges. In the early 1900s, it was President Roosevelt who worried that lumberman and fires would destroy the great western forests and deprive future generations of habitat and boards. He set-aside millions of acres from the sawyer’s blade and hired forest rangers who tirelessly stood watch over their nation’s investment.

It turns out, back then, that logging was not much of a problem for federal forests. Sure, logging happened, but federal forests were remote and demand for industrial wood was modest in an era when population and income were far lower. Nature was a bigger “problem,” as 41 million acres per year burned before 1945.

Government set about slowing these conflagrations, hiring hearty soles, including servicemen returning from World War II, to put up a fight. Despite serious setbacks, like the Mann Gulch fire in 1949 that took 13 honorable lives, brave hand crews, hotshots, smokejumpers, and the like cut fires to 3 million acres per year by the 1970s.

What happened to all that wood saved from fires? Much of it made its way into houses and other products when the federal government built up a massive timber harvesting operation in western forests to meet growing demand during the post-World War II economic boom. By the 1970s federal harvests constituted 22% of softwood timber production in the U.S. In communities across the western landscape, forestry became a way of life, with booms and busts regulated by the number of housing starts.

But in 1991, all this came to a stop when Judge Dwyer ruled against the Forest Service, requiring changes in logging practices to save endangered species. Practically overnight, logging ceased on federal lands throughout California, Oregon, and Washington. They have remained low ever since as the Forest Service shifted its perspective.

These changes could not have come at a worse time for the American economy, which grew apace in the 1990s. Timber prices soared to new highs but mill towns in Oregon and Washington saw little benefit as log piles diminished. In 1993, President Bill Clinton chaired a timber summit in Portland, Oregon to make good on an election promise, but his words could not mend the obvious: a deep structural adjustment was underway, driven by a new calculation that favored owl habitat over tree cutting on federal lands.

Fortunately, for aspiring homeowners in the US, lumber poured in from Canada. The Canadians had plenty of trees and were keen to sell them. Lumber prices came back down as imports ramped up to 30% of lumber consumption by the early 2000s. The proportion has fluctuated a bit but remained close to this level ever since.

The question now is, what happens if tariffs reduce wood imports from Canada? Will prices stay high or can the US increase wood harvesting enough to counteract the market effects?
Consider federal timber lands, which have more or less been left alone since the early 1990s. These forests come under direct control of the President, who signed an executive order directing agency heads to increase logging on lands they control.

Can the US go back to the industrial-scale logging in federal forests like the 1950s through 1980s when federal harvests routinely hit 2 billion ft3 per year? Let’s look at the numbers.

The US consumes 12-13 billion ft3 of wood per year. Lumber accounts for about 55% of that, or 6.9 billion ft3. In recent years, we have imported around 1.7 billion ft3 per year. This level is down from the early 2000s when a housing boom drove imports to 2.5 billion ft3. Today, federal harvests stand at about 0.3 billion ft3 per year.

In principle, the US is capable of significantly ramping-up wood production on federal lands. With data downloaded from the US Forest Service Forest Inventory and Analysis database, I estimate that federal lands contain over 300 billion ft3 of softwoods, the key wood type imported from Canada.

We cannot access all that wood, though. About 23% is set-aside in wilderness areas and other protected places. An additional 43% is older than 120 years or in locations with slopes greater than 50 degrees. In both these cases, there are good environmental reasons not to cut. An additional 2.5% of the wood is too young to cut, so perhaps only 102 billion ft3 on 33 million acres is actually available for harvesting in a way that may not cause significant environmental damage.

That is a lot of wood. Can we cut it?

One answer is “yes” because we are already losing lots it each year to fires, which have now expanded to 7.5 million acres burned per year. Between fires and pests, 1.4 billion ft3 (1.4%) are killed annually, due in part to simple neglect. More harvesting would reduce fire and pest losses with thinned and younger forests.

How much can we safely cut? Simply cutting what grows every year would amount to 0.9 billion ft3 of wood for markets. Considering that these forests have not been managed for over 30 years, I hypothesize that we can harvest more than 0.9 billion ft3 per year and the effect on long-term volume growth will be positive. Currently, I’m assessing this with the Global Timber Model, so will have some actual analysis on that in the future.

But the current reality is that a significant amount of wood can, and probably should, be cut on public land. Based on the current inventory, growth, and dieback, I estimate that we can access 0.9 to 1.3 billion ft3 per year sustainably in the next two decades. Harvesting would also reduce forest fires.

That said, there are risks. The Forest Service has laid off lots of workers recently, and it is not clear the organization now has the capacity to manage a large and growing timber sale program. Lots of public and private infrastructure, including roads, machinery, and mill capacity, must be developed. Labor in western woodsheds has been scarce for years, so higher output will increase wages and drive-up costs.

There are also environmental risks. Road building and logging will denigrate habitat and water quality. In the haste to log, I worry that these risks will not be weighed carefully.

The carbon effects are not clear. Moving federal forests to shorter rotation ages with more harvesting could have short-term negative consequence for carbon emissions, but if management reduces fire damage and promotes increased growth rates through thinning and reforestation, the effects could be positive.

There is a way to have positive effects on the atmosphere, but it is not obvious that the Forest Service still has the personnel to ensure this outcome. And it is unlikely that the private sector, which will do the logging, has right incentives to do it well. The idea of using federal lands for more timber carries big risks.

One question folks might ask is why not harvest more on private land? Most forests and timber in the U.S. are on private land. Higher prices from tariffs could induce more harvesting there, but the tariffs must remain in place to have an effect. Landowners have inelastic supply, meaning that private wood supply will change modestly in today’s on-again, off-again policy environment.

The wildcard here is the potential federal timber harvesting program proposed through executive action. If private landowners come to believe the administration can actually pull off sustained increases in federal timber supply, logging on private lands in the east will edge up in anticipation. There is a modest overhang of mature logs in eastern forests that could enter the market in the next few years before the federal program gets up and running.

In conclusion, tariffs on wood imports from Canada would raise prices for lumber in the U.S. in the short term. We have plenty of wood available on federal forestlands, especially in the west, to expand our supplies and make up for any losses from Canada. However, it has been decades since most of these public forests have seen large-scale timber harvesting operations. Increases in harvesting can provide environmental benefits in terms of fire control and even long-term carbon storage, but there are also environmental risks to species, habitat, and the atmosphere.

Reversing Deforestation in Latin America: How USAID has helped.

by

By Brent Sohngen (sohngen.1@osu.edu)

Watching the current turmoil at USAID is more than sad. Not only is it devastating to hard working people and their families in all corners of the earth, but it will also have long-term implications for the welfare of people in other countries where economic development sorely lags. Yes, we can ignore the plight of others and focus only on ourselves. But the America I know has never been like that. I hope it doesn’t change. I fear it has.

Let me give one example of the type of work of USAID does. You can read more about it and other examples in the book I co-authored with Douglas Southgate Reversing Deforestation: How Market Forces and Local Ownership are Saving Forests in Latin America (Stanford University Press, 2024).

For years, USAID has supported community forestry in the Maya Biosphere Reserve of northern Guatemala. I wrote a bit about this project in an earlier blog post: Is timber harvesting in the tropics sustainable?

Back in the 1990s as Guatemala’s long-running civil war came to a close, there was discussion about what to do with land in the north of the country. The area contained an enormous wealth of Maya history locked up in buildings covered by half a millennium or more of rainforest growth. Lots of people had moved to the area to escape violence and more people were coming in search of a better life. An agricultural frontier was moving north towards the region along the recently paved road, shifting forests to farmland with significant losses of cultural Maya relics to the private black market.

Some people argued the entire northern part of the country should be turned into a giant set-aside, or national park. Fortunately, their arguments didn’t prevail and a more pragmatic approach emerged. This approach included setting some parks aside, while at the same time creating community forestry operations – where forests would be managed for timber and non-timber forest products by local groups.

USAID supported this institutional approach of providing limited ownership of forestland for forest management. The limited ownership occurred in the form of 20-year contracts with local groups. USAID supported efforts to manage these forests scientifically, using forms of selective harvesting in 30- to 40- year rotations which would help maximize value and regeneration of the most important species, Mahogany.

USAID supported entrepreneurship at timber mills that would receive the logs and turn them into boards, sometimes drying them before shipping them to other parts of Guatemala or the world. Famous rock bands have used the wood for their guitars because it’s sustainable. With support from USAID, local business groups would meet periodically to develop marketing strategies.

I haven’t spent an enormous amount of time in northern Guatemala. But the time I have spent has taught me that entrepreneurial spirit is alive and well there. With limited ownership of the land and forest resources through community forestry, full ownership of timber mill capital, and an eager willingness to work, members of the community forestry operations were well off.

As part of my research, we have shown that these efforts slowed deforestation (Fortmann et al., 2017) and increased incomes (Bocci et al., 2018).

Maybe it would have happened without USAID. I don’t know? What I do know is that USAID helped it happen by adapting the time-honored U.S. model of fee simple ownership and encouraging local community ownership because they are philosophically consistent. Back in the 1990s, people in that organization sensed an opportunity to encourage local ownership and help local organizations become better business people.

Who knows what the “new philosophy” at USAID, or whatever some new agency like it is called, will bring? It’s got a tall bar to get over to beat what USAID accomplished in the past.