Planting trees helps fight climate change—but we need billions more seedlings

The U.S. must more than double the production of seedlings to meet reforestation goals, researchers say.

Planting trees has quickly emerged as a seemingly simple way to soak up carbon emissions. Everybody likes it: Environmentalists, politicians, and corporations alike are pushing for a rapid expansion of reforestation efforts to help meet climate goals.

This means growing trees—and lots of them—with the expectation that they’ll capture and store carbon dioxide and help prevent it from warming the world beyond the Paris Agreement target of 3.6 degrees Fahrenheit (2 degrees Celsius) above pre-industrial temperatures.

But according to a new study in the journal Frontiers in Forests and Global Change, there aren’t enough tree seedlings currently being grown, at least in the United States, to keep up with those goals. If reforestation efforts are to help tackle climate change, the study finds, tree nurseries across the U.S. will have to increase their production to at least three billion seedlings per year— more than double current levels. 

This needs to happen “sooner than later,” said the study’s lead author, Joe Fargione, science director for The Nature Conservancy's North America Region. “You can’t plant a tree until you grow it. And you can't grow it in the nursery until you have the seed.”

In order to better understand how to increase national tree production levels, Fargione and over a dozen other researchers surveyed 181 federal, state, and private nurseries and foresters last year, representing at least half of all seedling production in the U.S.

The results, released last month, show that the nation’s nurseries are currently producing 1.3 billion seedlings per year, which are mostly going to replace existing trees harvested by timber companies or lost to wildfires. To expand U.S. forests onto an additional 64 million acres identified by the study as ripe for reforestation—and carbon storage—would take another 1.7 billion seedlings a year. That brings the total needed from nurseries to three billion a year, more than a 130 percent increase.  

Ramping up seedling production that much, and making sure they live long enough to trap enough carbon emissions, will cost tens of billions of dollars, according to the study. It will require training specialized seed collectors and investing in new infrastructure, as well as bolstering long-term monitoring to ensure forests survive in the face of pests, disease, drought, and wildfires—threats that are all on the rise because of climate change.

Scaling up

Pressure to regrow and protect forests is at an all-time high. Last August, over two dozen local governments, companies, and nonprofits across the U.S. committed to the World Economic Forum’s initiative to globally plant a trillion trees by 2030. Last October, then-President Donald Trump signed an executive order committing the U.S. to that same goal. With such bipartisan support, some environmental nonprofits are hopeful the Biden administration will build on this initiative.

Beyond individual corporate or local goals, growing trees can contribute something to national climate targets. The land sector—which includes everything from tree planting and avoiding deforestation to increasing the amount of carbon stored in soils—accounted for a small portion of the U.S. Obama-era commitment to reduce emissions by up to 28 percent under the Paris Agreement. According to one estimate, if all 64 million acres identified in the study were reforested, that would represent roughly 7.5 percent of the emission reductions needed to meet the nation’s Paris Agreement commitments.

The current rate of reforestation, however, can’t even keep up with the amount of land that has been burned by devastating wildfires across the American West in recent years. Climate change is only expected to make wildfires more intense, which will increase that backlog.

“We’re just now recognizing the increasing backlog of areas that need to be planted that aren't being met yet,” said seed ecologist and study co-author Olga Kildisheva, a project manager at The Nature Conservancy.

Planting more trees to offset carbon emissions will further increase demand for seedlings. The good news, said Fargione, is that only a third of public and private nurseries surveyed are currently operating at full capacity. That means there’s a big opportunity to expand.

Seedling production peaked over 30 years ago. In the late 1980s, more than 2.6 billion seedlings were produced each year in the U.S. Once the 2008 recession shuttered many nurseries across the country, that number dropped to less than one billion. “Imagine losing 75 percent of your capacity,” said Dan Rider, associate director of the Maryland Forest Service, of the impact that the recession and other factors have had on the state’s John S. Ayton forest tree nursery. “Our story's not unique.”

 It’s going to take a lot of work to scale back up, said Eric Sprague, vice president of reforestation at American Forests, a conservation organization that helped spearhead the new study as well as the trillion-trees initiative. But doing so, he says, is “going to be a huge part” of whether or not the U.S. achieves its reforestation goals.

“It’s not just about expanding and improving what we have,” Sprague said, “but actually adding new nurseries to meet this goal.”

If all nurseries, both public and private, operated at maximum capacity, the study estimates an additional 400 million more seedlings could be grown each year. Researchers also expect a further 1.1 billion seedlings could be produced annually if the majority of nurseries expanded beyond their current capacity, which most surveyed in the study said they’d be willing to do. Add all of this to the 1.3 billion currently being grown, and production would be nearly at the three billion per year minimum that the study recommends.

Turning up the volume

Boosting seedling production and planting them means increasing support and investment across the entire process. As the study found, there has been “chronic under-investment” in specialized labor, infrastructure, and training. “Workforce challenges,” said Sprague, “are the number one barrier to scaling up.”

Seed collectors need to understand everything from predicting when certain species will release their seeds—making them available to gather—to how to safely clean seeds. Staff then need to be trained on how to test the seeds’ quality and store them so they stay viable over the years. “It's a perishable product; it needs to be treated carefully,” said study co-author Greg Edge, a forest ecologist with the Wisconsin Department of Natural Resources’ Forestry Division. Yet the number of people specializing in this work continues to dwindle.

Nurseries, meanwhile, rely only on a handful of year-round staff; the rest are seasonal workers who help with sowing, harvesting, sorting, and packing. It can be difficult to attract these workers, though, due to the remote locations of many nurseries, as well as competition from other agriculture jobs. Immigration policies can also affect the number of available workers, the study noted.

Not only are seeds and labor in short supply, but the infrastructure is old, said Charles Eckman, horticulturist at the federal J.W. Toumey Nursery in Michigan. And while adding or improving greenhouses can be a great way to expand capacity and grow seedlings more quickly than in the field, he said, it has to be planned years ahead of when the seedlings are needed. 

The upfront financial cost for nurseries can be a big risk. “We're trying to predict today, like literally right now, ‘Well, what's the market going to look like in two years?’” said Rider in Maryland. “In the nursery business you have to spend all of your money today, for site prep, fertilizer, and everything else that goes into the ground … and you won’t get that money back for two years.”

Planning for survival

A tree-planting campaign with stable, long-term funding—whether federal or private—could provide nurseries the certainty they need to ramp up production, experts agreed.

The Frontier study is based on the assumption that planting trees is the main way to meet reforestation goals, said Karen Holl, professor of environmental studies at the University of California, Santa Cruz, who wasn’t involved in the study. Protecting existing forests, as well as encouraging natural regeneration, shouldn't be forgotten, she said.

And even a tree-planting campaign can be doomed by a “misplaced emphasis on how many trees are planted rather than how many survive,” the study warned. It calls for developing guidelines on what seeds will thrive in different environments, especially as climate change shifts plant species to new regions.

“It's not just about planting a tree. It needs to be done thoughtfully and well, because you can't just stick a tree in the ground and come back in 100 years and have a forest,” said Edge. It takes an immense amount of money, labor, and patience to turn a seed into a sapling. “We don't want to just waste our time sticking a seedling in the ground that'll die.”

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