Workshop on Shortleaf Pine in the Southern Appalachians

Shortleaf pine and shortleaf-oak dominated stands have declined by more than half over the past few decades. Photo by Jim Guldin, USFS.

On March 3 and 4, 2020, about 25 silviculturists, foresters, fire management officers, timber specialists, and other USDA Forest Service experts gathered for a two-day workshop on shortleaf pine (Pinus echinata).

In the southern Appalachians, shortleaf pine restoration is a major priority for national forests and others. The species has an extensive range but its acreage has declined by more than half over the past few decades.

The group represented national forests in six states:

They were joined by Jim Guldin, a research ecologist and Station silviculturist. Guldin specializes in shortleaf pine and led two workshop sessions. He discussed management of mixed pine-oak stands, current research, and historic shortleaf pine ecosystems. A century ago, shortleaf pine often grew in open woodlands or savannas with plenty of native grasses at its feet. Fire frequently occurred on the landscape.

“Shortleaf pine restoration is not just about the tree, it’s about the whole system,” says Mike Black, who directs the Shortleaf Pine Initiative and discussed planting methods at the workshop. “Many of the plant and animal species in trouble need relatively open forests with sunlight and fire. Most of our forests today in the southeastern U.S. are heavily shaded and free of fire.”

Several experts from the Southern Region attended, including Janet Hinchee, regional pine silviculturist. Hinchee organized the workshop, facilitated the first day, and led sessions on seeding and ordering seed and seedlings.

Regional geneticist Barb Crane spoke about Forest Service seed orchards. She was joined by Robin Taylor, who retired as Forest Service seed orchard manager but still works part-time through the Agriculture Conservation Experienced Services Program.

The orchards provide seed for operational reforestation and restoration projects. Crane reported that the Forest Service operates 90 percent of all shortleaf pine seed orchards that exist in the South. Most of the orchards were established in the 1960s. The trees are getting old and instead of producing large seed crops every five to seven years, they produce bumper crops about every ten years. The seed orchards work with the National Seed Lab to test the viability of the newly collected seed. Seeds remain viable for as long as fifteen years.

To restore shortleaf pine through artificial restoration, “we are going to need more seed than what the orchards can provide,” says Crane. “If you don’t have seed, you can’t have reforestation and restoration projects.”

Ashe Seed Bank USFS
The Forest Service operates this seed bank in Mississippi, as well as 90 percent of all shortleaf pine seed orchards in the South. Photo by Barbara Crane, USFS.

In addition to starting new seed orchards (which would require a heavy investment in time and genetics expertise), seed could be obtained by planting genetically-improved seed, growing those trees to maturity, and collecting cones from them.

Seed production areas would be a second way to increase supply. In the 1970s, agency resource managers often identified stands that had mature trees of excellent form and evidence of cone production as “seed production areas,” as Guldin mentioned. The locations were recorded on administrative maps, and the stands may still exist — potentially providing a source of seeds that could be used for restoration.

In addition to sourcing seeds and seedlings, managers and technicians on the national forests may be responsible for mapping and managing tens of thousands of acres of potential and existing shortleaf pine and mixed pine and oak forests. Much of the workshop focused on the best strategies to:

  • Identify prime shortleaf habitat,
  • Prepare the site,
  • Plant the seeds or seedlings,
  • Control the trees and other plants that may grow faster the first few years,
  • Conduct prescribed fires, and
  • Monitor the site for decades (if all goes well, the trees will outlive the humans who planted them).

In the southern Appalachians, prime shortleaf habitat is often on lower elevations (less than 2,500 feet), away from carbonate-bearing rocks, on southern aspects, on low- to mid-slope positions, and slightly more convex than concave, according to the Simone Ecozone Model.

field tour shortleaf pine
Field tour showed a variable retention thinning and harvest, followed by natural regeneration of pitch pine and planted shortleaf pine seedlings. Rachael Dickson, Zone Silviculturist, Pisgah NF, and Jason Rodrigue, Forest Silviculturist, NFs of NC led the tour. Photo by Jim Guldin, USFS.

Jason Rodrigue, the forest silviculturist for the National Forests in North Carolina, discussed the model, which uses elevation, precipitation, aspect, and about 25 other variables to predict shortleaf habitat.

“As with any model, you need to align what it can do with what you need it to do,” says Rodrigue. “And although it’s not always accurate, it’s very useful. It provides a great starting point for shortleaf pine restoration projects.”

Shortleaf pine grows in dry, sandy, or rocky soils. And its seeds germinate best in bare mineral soil, so burning up the leaf litter and duff is sometimes part of site preparation when trying to regenerate the species with natural seedfall. “Good site preparation is important when planting shortleaf pine seedlings also,” says Guldin.

Herbicides can also be used to prepare sites for shortleaf. A one-time application of herbicide can kill unwanted hardwoods, grasses, and broadleaf herbaceous species, as Jim Bean of the chemical company BASF discussed at the workshop. Herbicides can be used as a stand-alone treatment though results may be better when herbicides are used in tandem with prescribed burning or hand treatments.

After the site is prepared and shortleaf pine is planted, fire is usually prescribed. Fire can control undesirable species and promote open forest conditions.

Shortleaf pine is a fire-adapted species. Below the soil, shortleaf seedlings twist in what’s called a basal crook. When the top is killed in a fire, the seedling re-sprouts from the basal crook.

“Historic photos show many mature shortleaf pine trees with two stems,” says Guldin. “These trees were top-killed by fire when they were seedlings.”

Fire also plays a critical role in maintaining the genetic purity of shortleaf pine stands, as previous SRS research has shown. Fire kills loblolly pine seedlings, and it also kills shortleaf-loblolly pine hybrids when they are seedlings. The hybrids do not have a basal crook and cannot re-sprout.

shortleaf pine seedlings resprout after fire
Shortleaf pine requires fire – and historically, many of the trees had two stems, indicating that they’d been top-killed as seedlings.

“Shortleaf pine stands growing near a loblolly plantation have the potential to produce a lot of hybrid seedlings,” says Guldin. “Some hybridization has likely always occurred, but without regular fire, the rates increase drastically.”

Scientists suspect that a warmer climate is contributing to increased hybridization.

With cool spring temperatures, loblolly pine pollinates about three weeks earlier than shortleaf pine. But if spring temperatures are abnormally warm, shortleaf cones can be receptive to pollination earlier, perhaps when the loblolly pollen is still in the air.

Prescribed fire can be difficult to implement. For example, on some national forests, such as the Chattahoochee-Oconee, there are about ten burn windows a year. Burn windows are days when fuel moisture, weather conditions, and other variables are balanced so the prescribed burn will be safe and effective.

“I hope prescribed fire will be a big part of what we do on the George Washington and Jefferson National Forests in Virginia,” says Kevin Kyle, the zone silviculturist on the forest. “But it is a challenge, and we’ll probably use herbicides for some site preparation work.”

Over the next ten years, Kyle and his colleagues plan to plant about 100 acres of shortleaf pine each year. “We’re bringing in a research component,” says Kyle. “We’ll be collaborating with SRS researcher Tara Keyser to look at reforestation including natural establishment, establishing native grasses, and fire frequency.” Other SRS research includes a burn prioritization model that Joseph O’Brien developed with the Chattahoochee-Oconee National Forest.

After just a year or two of growth, most shortleaf pine seedlings can survive fire. But exact mortality rates are unknown, and some managers wait until the seedlings are ten years old before burning.

The need to burn means silviculturists and fire management officers must collaborate. “These relationships tend to be better on smaller districts where people interact more,” says Hinchee. “But if the lines of communication aren’t there, just initiate them. And be mindful of jargon – for example, the word prescription has different meanings to a silviculturist and a fire management officer.”

shortleaf pine on Ouachita NF
This stand of shortleaf pine was planted on the Ouachita National Forest, Arkansas, in 1984. More than six prescribed fires have been conducted since then. Photo by Jim Guldin, USFS.

On the Nantahala National Forest, district silviculturist Sarah Bridges and district fire management officer Chad Cook collaborate often – and presented information together at the workshop.

“We are seeing on the ground that site competition is more effectively controlled when the site is burned only a few years after planting,” says Bridges. “But there are unknowns: How often is it safe to top-kill seedlings? Can we create favorable conditions without top-killing the seedlings?”

In the early stages of a restoration project, Bridges works closely with contractors, who are paid to manually fell the non-merchantable trees to get the site preparation done quickly.

Shortleaf pine restoration may begin with a clearcut. Clearcuts can be ugly and may seem counter-intuitive. But clearcuts are a management tool that is rarely used today except for restoration purposes.

For example, on the Andrew Pickens Ranger District in the Sumter National Forest, hundreds of acres of loblolly pine plantations are being cut down, in accordance with their Forest Plan objectives. The plantation sites were historically shortleaf pine habitat, and shortleaf will be restored.

Read more about shortleaf pine in CompassLive.

For more information, email Jim Guldin at james.guldin@usda.gov.

Access the latest publications by SRS scientists.

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