Genetics of Shortleaf and Longleaf Pine in Seed Orchards

Shortleaf pine (Pinus echinata) and longleaf pine (Pinus palustris) ecosystems have been dwindling for decades. Restoration is a huge priority for the USDA Forest Service, the Longleaf Pine Alliance, the Shortleaf Pine Initiative, and many others. Restoration requires seed, and on National Forest System lands the seed comes from USDA Forest Service seed orchards. The…  More 

Silviculture to Restore Southern Fire-Adapted Pines

Native, mature southern pine ecosystems are dwindling on the landscape, and the plants and animals that depend upon them are in trouble as well. “Living and working in Arkansas, I sometimes forget that shortleaf pine as far as the eye can see is uncommon outside of this area,” says USDA Forest Service scientist Jim Guldin.…  More 

Hybrids in the Seed Orchards

Shortleaf pine is under siege, and one of the threats has emerged in seed orchards. “In some shortleaf seed orchards, 10 percent of trees are hybrids,” says U.S. Forest Service research geneticist Dana Nelson. “Although the majority we’d consider shortleaf pine, even a few hybrids is enough to raise concern.” To some extent, shortleaf and…  More 

Shortleaf Pine: The Future Requires Fire

Shortleaf and loblolly pine are closely related and have always hybridized occasionally. “However, hybrids are now so common that they may threaten shortleaf pine’s existence as a genetically distinct species,” says U.S. Forest Service scientist Dana Nelson. “Our study is the first to show that fire helps maintain genetic distinctions between shortleaf and loblolly pine.”…  More 

The Role of Humans in U.S. Plant Invasions

Plant breeders have produced hybrids for centuries, maybe even millennia, crossing genetically different varieties or species to accentuate desired traits. Plants continuously hybridize on their own, either within populations of their own species or across species, families, and even genera. As exotic introduced plants began aggressively spreading into areas where they weren’t wanted, plant biologists…  More 

As Pollen Clouds Drift in, Native Pine Trees Hybridize

The natural range of shortleaf pine is vast, spanning 22 states. The tree grows as far south as Texas and as far north as New York, often in association with other native pines such as loblolly. Shortleaf and loblolly pines’ natural ranges overlap, although they tend to prefer different site conditions. Loblolly usually grows on moister…  More 

Shortleaf Pine: A Species Slipping Away?

Both shortleaf and loblolly pine are native to the southeastern United States, where the two species have coexisted and occasionally hybridized for millennia. Historically, hybrids were rare. In the 1950s hybrids made up just 3 percent of the pines in shortleaf stands, but since then their numbers have skyrocketed. Today, just two or so generations…  More