The REPLANT Act is an initiative started in 2021 that aims to provide money for the US Forest Service to plant over a billion trees during this decade in an effort to mitigate climate change, protect water, clean the air, and cool cities.
Other regions of the world have also recently launched similar initiatives, with major government and private entities actively investing in tree planting. For instance, the World Economic Forum is planning to help plant a trillion trees around the world by 2030.
Unfortunately, according to a recent study led by the University of Vermont (UVM), such efforts to plant trees in the U.S. are at risk due to an undersupply of seedlings and a lack of species diversity.
“Trees are this amazing natural solution to a lot of our challenges, including climate change. We urgently need to plant many millions of them. But what this paper points out is that we are woefully underserved by any kind of regional or national scale inventory of seedlings to get the job done,” said senior author Anthony D’Amato, an expert in Forestry at UVM.
The researchers examined 605 plant nurseries across twenty northern states, and found that only 56 of them grow and sell seedlings in quantities sufficient for conservation and reforestation efforts and only 14 of them were government operated. Moreover, the scientists identified an overwhelming scarcity of seedlings from different species that would be adapted to local conditions and climate.
Instead, forest nurseries tended to maintain a limited inventory of just a few species, prioritizing those valued for commercial timber production over species necessary for conservation, climate adaptation, and ecological restoration.
In addition, many nurseries had no locally adapted tree stocks available, and among the seedlings that they grew there were insufficient types of trees and “future-climate-suitable” genetics to meet the conservation and restoration goals in a warming climate.
“The world is thinking about a warming climate – can we plant towards that warming climate? We know we’re losing ecologically important species across North America and around the world. So, the goal is: can we restore these trees or replace them with similar species? It’s a powerful idea. But – despite the excitement and novelty of that idea in many policy and philanthropy circles – when push comes to shove, it’s very challenging on the ground to actually find either the species or the seed sources needed,” said lead author Peter Clark, an applied forest ecologist at UVM.
“The number of seedlings is a challenge, but finding the diversity we need to restore ecologically complex forests – not just a few industrial workhorse species commonly used for commercial timber operations, like white pine – is an even bigger bottleneck.”
One example of an ecologically important species that has been under stress for decades from climate change, land clearing, and pests and needs urgent restoration is the red spruce.
To meet red spruce restoration goals, we currently need many millions of seedlings. Unfortunately, the analysis revealed that only two tree nurseries had inventories of this critical species.
“Remarkably, only 800 red spruce seedlings were commercially available for purchase in 2022 – enough to reforest less than one hectare,” the authors reported. “It really points to just how bare the cupboard is when it comes to the diversity of options, but also the quantity that’s needed to make any meaningful impact,” D’Amato added.
To address these issues, many regional nurseries urgently need to dramatically increase both seedling production and diversity. However, in regions where nurseries have declined over recent decades – such as the Northeast – investments in growing new, future-climate-adapted seedlings may carry significant financial risks.
Additionally, seedlings brought in from outside a specific region are less likely to succeed. This is a situation most nurseries from the northern states are currently facing. The North Central states produce over 80 percent of the seedlings grown there, while the northeastern states produce very few.
“Such concentration of production will hinder tree planting efforts because species and seed sources likely originate from similar geographic or bioclimatic zones,” the authors explained. Finally, since seedlings are also highly sensitive to stress, a misalignment between when they are available and when they are needed may also diminish their chance of success.
Since government agencies currently lack clear policies about the movement of tree species and tree genetics – frequently relying on seed zones established in the 1970s – updated guidelines for moving species under an increasingly warm climate are needed, along with efforts to diversify species and climate-adapted seed-sourcing.
Although in 2023 the federal government made an investment of $35 million in expanding federal nursing capacity, considering the existing reforestation backlog, declines in nursery infrastructure, and complex needs for a diversity of seeds and seedlings, more public investment in the form of loans, grants, or cost-share programs will be necessary to diversify and expand nurseries.
“People want trillions of trees, but often, on the ground, it’s one old farmer walking around to collect acorns. There’s a massive disconnect,” Clark concluded.
Planting trees to mitigate climate change represents a cost-effective, widely implemented strategy. This simple yet effective process has the potential to sequester large amounts of atmospheric carbon dioxide (CO2).
This climate change mitigation strategy involves the cultivation of trees on a large scale to absorb CO2, a significant greenhouse gas, through the natural process of photosynthesis.
This strategy effectively reduces the overall amount of CO2 in the atmosphere. As a result, it helps to alleviate the impacts of climate change.
Trees serve as natural carbon sinks, absorbing CO2 from the atmosphere and storing it in their biomass (trunks, branches, leaves, and roots) and in the soil. The rate of carbon absorption or sequestration varies among tree species.
Faster-growing species generally sequestering more carbon than slower-growing ones. Mature, healthy forests tend to sequester more carbon overall than young or degraded forests, emphasizing the importance of not only planting new trees but also preserving existing forests.
By absorbing CO2, trees sequester carbon, thereby reducing the overall concentration of greenhouse gases in the atmosphere.
Tree planting creates habitats for numerous species, promoting biodiversity.
Trees help to prevent soil erosion and maintain soil health.
The process of planting and maintaining trees can create jobs and stimulate local economies.
Tree planting ideally takes place in sites that previously hosted forests but have since experienced deforestation or degradation.
The selection of tree species depends on the specific climate, soil type, and biodiversity goals of a given area.
Trees require proper planting techniques and ongoing care to ensure survival and growth.
Despite the clear benefits, tree planting for climate change mitigation also faces challenges. These include:
Newly planted trees often have low survival rates, due to factors such as inappropriate site or species selection, poor planting techniques, or lack of follow-up care.
It takes many years for trees to grow large enough to sequester significant amounts of carbon.
Ongoing deforestation and forest degradation can negate the benefits of tree planting.
Various international, national, and local initiatives promote tree planting to mitigate climate change. Policies often include incentives for tree planting and penalties for deforestation. Implementation involves partnerships among governments, non-governmental organizations, corporations, and local communities.
Planting trees to mitigate climate change represents a crucial strategy in the fight against global warming. While it is not a stand-alone solution, it complements other efforts, such as reducing fossil fuel emissions.
As such, the benefits of tree planting for climate change mitigation extend beyond carbon sequestration, contributing to biodiversity, soil conservation, and economic development as well. Effective implementation, however, requires careful planning, long-term commitment, and the inclusion of tree planting as part of a comprehensive approach to climate change mitigation.
The study is published in the journal BioScience.