Reviving a Southern Icon: How Science is Securing the Future of Longleaf Pine

Once stretching across more than 90 million acres of the southeastern United States, the longleaf pine is more than a botanical relic — it’s a living emblem of the region’s ecological and cultural identity. After centuries of neglect, this iconic species is experiencing a revival, driven by renewed conservation efforts and a deeper understanding of its environmental significance. But restoring the longleaf isn’t just about planting more trees. It’s about planting the right trees.

That’s where science and strategy step in. In 2024, the Cooperative Tree Improvement Program (TIP) at North Carolina State University joined a five-year project with The Longleaf Alliance to build a robust, genetically diverse archive of adapted longleaf pine trees that will supply seeds capable of sustaining the species across its historic range, from the coastal plains of Texas to southern Virginia. 

Funded with a grant from the National Fish and Wildlife Foundation, the project focuses on building a reliable source of improved planting material of longleaf pine trees selected for broad adaptability, disease resistance, and a variety of economically important traits. Seed from the selected trees will meet the wide diversity of landowner objectives when establishing plantations. The selected trees will be established in specialized seed orchards, which are poised to supply the seeds needed for large-scale restoration efforts.

“The primary objective of the project is to secure well-characterized, locally adapted genetic material for longleaf pine,” said TIP co-director Trevor Walker, the project’s principal investigator and an assistant professor in the Department of Forestry and Environmental Resources. “This material will support future seed orchards, improving seed supply and genetics for restoration efforts.”

Restoring longleaf pine ecosystems is vital economically, culturally and historically. These forests support timber, wildlife and recreation and help boost local economies. They also hold deep cultural meaning for Indigenous communities and reflect the heritage of the southeastern U.S. Once widespread, longleaf pine forests were heavily lost to logging for timber, naval stores and agriculture and misguided fire suppression policies, so their restoration helps revive both the environment and cultural connections.

Building a Strong Genetic Foundation

At the heart of the project is the establishment of second-generation seed orchards populated with genotypes identified through rigorous progeny testing. A progeny test is a type of field trial where offspring from numerous parent trees are grown side by side in a common environment. This helps identify which traits are under genetic control rather than environmental, which is essential for choosing the best parents for future orchards.

TIP planted a progeny test series in 2011 with 6,500 longleaf pine trees to evaluate the growth, health and adaptability of different genetic lines. The trees in these tests originate from a wide range of genetic backgrounds, including wild seed sources from Alabama, Georgia, North Carolina and South Carolina, as well as breeding programs led by the North Carolina Forest Service, the U.S. Forest Service, and other partners. 

By carefully analyzing trial data, TIP staff are working to identify trees with the strongest and most desirable traits, removing any prone to defects like forking or diseases such as pitch canker and fusiform rust, which can harm pine forests. From the healthiest trees, they focus on families with the greatest potential to pass on good traits, inspecting the top trees in each group for straightness, disease resistance, branching and growth to ensure quality and long-term forest health. The result is the selection of superior trees from the most desirable families.

In essence, the “best” trees are those that not only grow well but also withstand disease pressures. This multifaceted selection process ensures a genetically diverse and reliable population of longleaf pines with strong traits. As Walker said, “You cannot determine genetics just by looking at the tree; instead, you evaluate its progeny. By looking at how hundreds of offspring perform, we can figure out if a tree was a good parent. Then, we decide whether to keep or remove it.”

TIP staff, collaborating closely with the North Carolina Forest Service, have so far made 54 selections for the genetic archive. Of these, 48 come from TIP’s progeny test series planted in 2011. The selections are expected to grow an average of 2.3 feet taller at age eight than trees from non-improved wild sources, and those prone to diseases like pitch canker and fusiform rust or undesirable traits such as excessive forking have been culled. 

Balancing Growth, Genetics and Stakeholder Needs

With ambitions to make 300 selections by 2028, TIP is navigating a complex intersection of ecological goals and the practical demands of those who manage and depend on forests. Balancing these often competing priorities requires careful consideration and a strategic approach to tree improvement.

Tertius Venter, TIP’s longleaf tree improvement manager and one of the project’s co-investigators, explained that selecting the right longleaf pines is complex due to their wide range in the southeastern U.S. A survey he conducted showed stakeholders have differing priorities, making it essential to understand their needs before choosing which traits to prioritize.

Despite this diversity, certain traits consistently rise to the top. “Everybody mostly wants a fast-growing tree that produces good wood, is adapted to the planting site, and is disease-free or disease-resistant,” Venter said. However, the selection process isn’t uniform across all regions or stakeholders. Some prioritize faster growth, while others emphasize conserving a broad genetic base to maintain the population’s health, resilience and naturally superior timber properties.

“It’s about combining science with stakeholder input to make sure we’re growing trees that are not just better, but truly right for their environments.”

This is where the science gets intricate. Venter explained that even in populations that generally grow slowly, some superior individuals exist. TIP aims to conserve those trees while also capturing other traits to ensure the population remains representative and genetically diverse. “The trees we select have to reflect the diversity of the population, make economical and ecological sense, and not just be the fastest growers,” he said.

TIP’s balancing act between enhancing growth and preserving genetic diversity exemplifies a forward-thinking strategy that respects both ecological complexity and meets the varied needs of those who rely on them. “It’s about combining science with stakeholder input to make sure we’re growing trees that are not just better, but truly right for their environments,” Venter said.

Reproducing Superior Longleaf Pines for Genetic Preservation

To preserve and propagate its longleaf pine tree selections, TIP employs grafting. Grafting allows foresters to replicate specific trees with known and desirable traits by transferring scions, or cuttings, from those trees onto robust rootstocks. This process creates multiple copies of selected trees, ensuring that the valuable genetic gains identified through progeny testing are maintained intact.

In a natural forest stand, even if a single tree produces ideal cones with traits such as superior growth, disease resistance, or desirable needle characteristics, collecting cones from that one tree is limited. “If we can take cuttings from that tree and graft them, we can create 100, 1,000, or even more copies, and that’s exactly what we do,” said former TIP director and professor emeritus Steve McKeand, who now serves as one of the project’s co-investigators.

Recently, with the generous donation of 300 slash pine rootstocks from Rayonier’s Georgia facility, McKeand and other TIP staff, along with Rayonier nursery personnel, grafted longleaf pine scions, achieving an 86% success rate. These grafted trees now form a genetic archive that will serve as the foundation for new grafted seed orchards. 

These grafted seed orchards are especially valuable because they offer more reliable cone production, higher seed germination rates, and, crucially, produce seeds of known genetic origins. In contrast, wild collections are a genetic gamble, especially for a species whose survival hinges on its ecological fit. Like many widespread tree species, longleaf pine has evolved genetic populations adapted to specific regions, meaning seedlings from one region may not thrive when planted in another.

Grafted seed orchards are strategically established on land with ideal soil and climate to maximize the production of genetically superior seeds, according to McKeand. Unlike timber plantations, their design and management prioritize seed yield with known genetic quality.

One of the standout features of a seed orchard is its genetic diversity, typically containing 15 to 30 different pine selections to boost seed yield and adaptability. As McKeand said, using locally adapted seed is crucial. “The number one criterion is making sure the seedlings that arise from these orchards are adapted. If I’m planting longleaf pine in the northeast central part of North Carolina, I don’t want the seed to come from South Alabama. It’s just not going to be adapted.”

Beyond environmental adaptation, seed orchards offer something natural stands simply can’t: reliability. “There’s nothing wrong with collecting cones from natural stands, but it’s really unpredictable,” McKeand admits. “One year you might get 100 bushels of cones, and the next year, none at all. In a seed orchard, you can control pests, maintain large crowns, fertilize and even irrigate, so it becomes a much more dependable source of seed.”

Championing Open-Source Genetics for Longleaf Pine

Establishing grafted seed orchards is not the end goal, but a step toward a broader objective. The project ultimately aims to progress from the initial selection phase to developing a sustainable, collaborative breeding system. If this approach succeeds, it will resemble TIP’s existing loblolly pine program, where members manage seed orchards and genetic archives, collect and grow seed, plant test sites, and continue the process of forward selection.

Importantly, the project prioritizes open-source access to the longleaf pine genetic material. Once established, the improved trees will be made available to the broader seed orchard community in the form of scionwood, fostering collaboration and amplifying restoration impact across the longleaf range. Scionwood provides the genetic material for grafting, allowing stakeholders to propagate trees with desirable traits that improve growth, resilience and adaptability in future orchards.

“This is a genetic resource for the community. The goal has always been to secure these materials so others can establish seed orchards, produce large quantities of seed, and use that seed for restoration,” Walker said. “It’s not about exclusivity; it’s about collaboration. We don’t want to give the impression that this is only available to a select few. It’s truly open source, a resource for anyone willing to do the work.”

In a field often driven by proprietary genetics and restricted access, this open-source approach stands out. For TIP and the broader community of researchers and land stewards, making these select trees widely available isn’t just a philosophy; it’s a practical strategy for large-scale restoration and long-term success. “If you try to do it on your own, it’s a big job, and it probably won’t get done,” McKeand said. “But if we share and work together, you know what they say: a rising tide lifts all boats.”

The roots of this openness run deep, as many of these improved tree genetics were developed through publicly funded programs. “The vast majority of the longleaf genetics work has been done by the U.S. Forest Service, the North Carolina Forest Service, and other state forestry agencies,” McKeand said. “They don’t want to hand it over to a seed company that keeps it locked away. They want it in the community. It was developed with public money, so there’s an obligation to keep it public.”

Restoring Longleaf Pine Through Shared Research and United Efforts

As the project continues, collaboration will be essential. In fact, efforts to restore longleaf pine rely heavily on genetic resources maintained by the U.S. Forest Service. The federal agency manages most of the longleaf pine seed orchards in the southern U.S. and has collected genetic material from across the species range. 

These orchards represent years of research and experimentation and form the foundation for current restoration efforts, according to McKeand. “The work being done now is based on years of research by federal and state agencies that identified selections from seed orchards established through previous trials,” he said. 

Current work involves selections from 120 families, but this is only a fraction of the genetic material preserved by the U.S. Forest Service. “We collected cones from 120 families, but the Forest Service has progeny from over 700 parents in trials,” McKeand said. “It is a large genetic resource that is currently underutilized. We are trying to access and revive it, or it may be lost.”

Decades ago, many efforts to improve longleaf pine trees were mostly abandoned, partly because the species was not widely planted or favored by many people at the time. Only a small number of people were planting longleaf pine, mainly due to the type of seedlings being used, which often did not survive well. As a result, the outcomes were usually disappointing.

“With the right science and the right partnerships, we can give longleaf pine the future it deserves.”

In recent years, however, there’s been a shift. Over the past 30 years or so, the use of containerized seedlings has increased significantly. These seedlings perform much better, with survival rates that are far superior to those of the past. Because of this, landowners who have always wanted to plant longleaf pine are finally seeing success. Longleaf pine currently accounts for about 10% of all trees planted in the South.

Some of the genetic trials established by the U.S. Forest Service 25 to 35 years ago remain intact today, and it’s crucial that TIP makes selections from these trials while the opportunity still exists. If not, these valuable sites risk being overtaken by housing developments, roads, wildfires, diseases or insect infestations. “Unfortunately, nothing good tends to happen to these trials after about 20 years. So, our mission is to recover and protect that valuable genetic material before it disappears forever,” McKeand said.

McKeand emphasized the potential value of these genetic resources: “There are 742 parents tested, and selecting from the top 300 or so would provide a significant genetic base with diverse traits. Such diversity is crucial for adapting to changing environmental conditions and meeting future demands, ensuring that these genetic resources remain valuable and effective for future use in tree breeding.”

Building on this foundation, the collaboration between TIP, The Longleaf Alliance, the U.S. Forest Service and other partners ultimately represents a strategic investment in the future of forestry and conservation. “This project is about more than trees; it’s about resilience, adaptability, and restoring a critical part of our southeastern ecosystems,” Walker concluded. “With the right science and the right partnerships, we can give longleaf pine the future it deserves.”