We need billions more baby trees to regrow US forests

On Earth Day last year, President Joe Biden called for the inventory, restoration, and conservation of mature and old-growth forests on federal, state, Tribal, and private lands. Forests are important in enhancing resilience to climate change, but they are also vulnerable to its impacts. The wildfires in 2020 and 2021 alone increased reforestation needs by over 1.5 million acres, highlighting how crucial it is to develop a plan to restore forests on a major scale.

In accordance with Executive Order 14072, agency-specific reforestation targets totaling over 2.3 million acres by 2030 were set on federally managed lands. There is also a goal to plant more than a billion trees over the next decade. However, a significant factor may stand in the way of these ambitious planting and restoration goals—the massive undersupply of seedlings.

Tree nurseries lack seedling availability and diversity

According to a recent study published in Bioscience, local tree nurseries lack the seedling availability and diversity needed to meet these lofty environmental goals. Authors from different institutions, including universities, US Forest Service research stations, and local departments of natural resources, analyzed more than 600 plant nurseries across twenty northern states and found that only 56 of them grow and sell seedlings in the volumes needed for conservation and reforestation. 

[Related: What successful forest restoration looks like.]

This scarcity is a product of several factors, like how few forest nurseries exist, says author Peter W. Clark, a postdoctoral associate in the Rubenstein School of Environment and Natural Resources at the University of Vermont. Many state and federal nurseries have closed due to the inability to cover costs through nursery sales.

“The US Forest Service used to maintain 59 federally funded nurseries, but now there are only six, with only one serving the entire 20-state region we examined,” says Clark. Although private nurseries play a key role in supporting the market, publicly-funded nurseries produce important species for conservation and restoration purposes, he adds.

A 2021 study published in Frontiers in Forests and Global Change identified 26 million hectares of natural and agricultural lands with reforestation potential across the contiguous US. The authors reported that reforesting this area by 2040 with 30 billion trees would require a 2.3-fold increase in current nursery production levels of 1.3 billion seedlings per year. In short, the number of tree seedlings produced each year must increase by 1.7 billion.

“Much research has emphasized that the volume of seedlings produced in US nurseries is far too low to meet reforestation targets,” says Clark. “We support these findings but add the finer point in that the types of seedlings are highly homogenous.”

He adds that nurseries operate in a free-market economy and tend to favor species that are more economically viable for sales—think conifer species for commercial timber purposes. It’s risky to maintain a broad inventory of diverse species that might not sell, especially since seedlings take one to five years to grow to be ready for resale. However, this dismisses the vast diversity of tree species needed to meet other ecological targets like carbon mitigation, ecosystem restoration, or assisted migration.

In the aforementioned Bioscience study, the authors found that commercially valuable tree species were commonly available, but the majority of other species were challenging to source and produced in low numbers. For instance, only two out of 56 nurseries sold red spruce, a culturally and ecologically important tree species in need of restoration, says Clark. About 800 seedlings were available for purchase, which can only reforest one to two acres. 

Limited seed sources or genetic diversity among the species is also an issue. “Even for northern red oak or eastern white pine, two of the most commonly propagated commercial tree species in the region, we found that seed was collected from less than one third of the available seed collection zones,” says Clark. “In other words, just a few trees were contributing to the genetic diversity of all nursery grown seedlings.”

Federal investment and workforce development can boost public tree nurseries and seed collection efforts

The federal government has invested $35 million to rehabilitate the aging National Forest System nursery and seed infrastructure, putting another $10 million to support state and Tribal nurseries and fund native seed partnerships. However, Clark says more public investment like grants, loans, and cost-share programs will be needed to expand forest nurseries and address the growing reforestation backlog. Funding to support research on producing species and genotypes that are better capable of withstanding the effects of climate change is also needed, he adds.

Seedling inventories often favor commercial species over the production of diverse, climate-adapted inventories because the former involves a lower financial risk, even though the latter has a higher reward in terms of ecological diversity, says Clark. “Although nurseries operate based on market demands, in the context of planting for global change, it may be better to simply invest in nurseries to supply seedlings just for the common good,” he adds. 

[Related: Tropical forests rebound on farm land blessedly fast.]

Increasing seed stock diversity is an important goal that requires increased seed storage capacity and a trained workforce of seed collectors, says Joe Fargione, science director at The Nature Conservancy. However, labor shortages and aging demographics among professionals in the field, like foresters, seed collectors, transport crews, and extractory staff, and nursery growers, are among the biggest limitations for scaling forest seed collection, says Clark.

To fill the skilled-labor gap and prevent the loss or degradation of institutional knowledge, recruiting new workers in these fields is necessary. “Funding and job-training programs may be needed to serve as economic drivers for job creation while potentially providing renewed access to nurseries in underserved areas,” he adds. Fargione says workforce development programs can ensure there are no bottlenecks in the supply chain.

Nurseries also need to ensure high-quality records of seed origin are readily obtainable for buyers so they can identify its adaptation potential under rapidly changing climatic conditions, says Clark. Forest trees are adapted to different climatic conditions, and they must be matched to the conditions of their reforestation or restoration sites. Developing a national seed-labeling standard and database with high-resolution records of source collections, such as latitude, longitude, and elevation, would improve seedlot selection, he adds. The Department of Agriculture currently has a Seedlot Selection Tool, but it is limited to the western US, Canada, and Mexico.

“By planting with an eye on diverse ecosystem functions, cultural needs, and climate adaptability,” says Clark, “we can meet multiple objectives that result in more resilient future forests capable of withstanding a greater degree of uncertain future conditions.”