Pro-B: A Practical Management Tool for Implementing Selection Silviculture

by Zoё Hoyle, SRS Science Delivery Group
A longleaf pine stand on the flatwoods of Goethe State Forest in north central Florida treated with single-tree selection using the Pro-B method. Photo by Dale Brockway.

A longleaf pine stand on the flatwoods of Goethe State Forest in north central Florida treated with single-tree selection using the Pro-B method. Photo by Dale Brockway.

Pro-B, a method developed by U.S. Forest Service research, helps make uneven-aged management of longleaf pine and other forest types a practical and efficient option for landowners and managers. A field study by researchers showed that after less than three hours of training on the Pro-B (proportional basal area) method, managers were able to accurately mark stands using only a single marking pass.

Dale Brockway, research ecologist with the Forest Service Southern Research Station (SRS) Longleaf Pine Restoration and Management unit, worked with SRS emeritus scientist Ken Outcalt and Auburn University’s Ed Loewenstein (formerly of the Forest Service Northern Research Station) to create a technique that managers can easily use to apply uneven-aged management in the forest. Pro-B may be used to implement selection silviculture in a variety of forest types in the Southeast, elsewhere in North America, and perhaps on other continents as well.

Uneven-aged management (single-tree selection and group selection) is sometimes considered the more “natural” way to manage forests and involves selecting trees to harvest based on values such as protecting native plant communities, maintaining continuous forest canopy cover through time, and facilitating the development of large, old trees while providing a reliable supply of quality timber products.

“In the past, longleaf pine was mostly managed with even-aged methods such as shelterwood, and even thought to be too intolerant for uneven-aged silviculture, though recent evidence suggests that it’s a viable alternative,” said Brockway. “Even-aged methods were better developed than uneven-aged approaches, and earlier uneven-aged methods seemed to be too complicated and constraining for longleaf pine management.”

The researchers developed a method based on basal area, the cross-sectional area at breast height (4.5 feet) of all trees summed per unit area within a stand. Pro-B apportions stand basal area into a 1:2:3 ratio among three broad tree diameter classes, combining smaller diameter classes into three ecological and product-relevant categories. This requires tree markers to remember only three fractions as they mark the fraction of trees that should be removed in each broad diameter class.

The researchers conducted a study on two longleaf pine site types (flatwoods and uplands) in 18 stands on the Florida Coastal Plain to examine the effects of applying Pro-B on pine regeneration, stand development, and volume growth while observing how easily the method could be learned by managers from a range of professional backgrounds.

Results from two training workshops, which included field applications where managers marked trees to be harvested, confirmed the ease of learning and using the Pro-B method, and preliminary findings about its treatment effects are promising.

“Early results show that using Pro-B, managers achieved the target residual basal area with a high level of precision,” said Brockway. “Although our results suggest that Pro-B is an effective method for applying uneven-aged management to longleaf pine stands, one or more cutting cycles will be needed before its regeneration success can be more fully evaluated.”

Pro-B allows managers to retain large trees that enhance structural diversity and improve wildlife habitat, and to leave trees with abundant seeds or good form while removing less desirable trees and adjusting the spacing among retained trees. Pro-B provides guidance for thinning toward a stable stand structure while allowing for periodic removal of high quality forest products on a 10 to 15-year cutting cycle.

For more information, email Dale Brockway at

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James Barnett Inducted into LSU Forestry, Wildlife, and Fisheries Alumni Hall of Fame

Adapted from Hall of Fame commentary

05.20. BarnettOn April 25,  James Barnett (left, with Larry Stanley) was inducted into the 2015 Louisiana State University (LSU) Forestry, Wildlife, and Fisheries Alumni Hall of Fame in recognition of the nearly five decades he’s spent conducting research for the U.S. Forest Service Southern Research Station. The work he’s done to improve the success of reforesting major pine species of the southern United States — and more importantly, the dissemination of the practical implications of that research — has truly set Barnett above his peers.

Barnett has authored and co-authored more than 350 publications and 200 professional presentations that target his scientific peers, reforestation experts working in the field, and nursery managers growing seedlings. His work in seed physiology, container and bareroot seedling production, seedling establishment, and plantation ecophysiology and management has set the standards for reforestation of southern pine ecoysystems. Recognized as a world authority on reforestation issues, Barnett has given keynote presentations around the world.

Barnett’s research contributes to the annual production of over 1 billion seedlings in the southern United States to establish the plantations that provide the majority of the United States’ solid wood and fiber needs — and to provide the seedlings needed to restore longleaf pine forests in their former range.

Barnett has leveraged the expertise he garnered throughout his career to provide highly productive leadership at regional, national, and international levels. He has effectively motivated interdisciplinary groups of scientists from the federal, state, academic, and private sectors to address issues important to the long-term sustainability of pine ecosystems in the southern United States. He’s forged partnerships and cooperative agreements to effectively use resources to solve real-world management problems.

In addition to this recent honor from LSU, Barnett has been recognized by the Secretary of the U. S. Department of Agriculture, named a prestigious Fellow and recipient of the Barrington-Moore Award by Society of American Foresters, deemed an Outstanding Alumnus by Louisiana State University School of Renewable Natural Resources (RNR), and has received numerous other awards from the Forest Service. 

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Understory Restoration in Longleaf Pine Ecosystems

by Sarah Farmer, SRS Science Delivery
Longleaf pine stand in the Croatan National Forest, North Carolina. Photo by David McAdoo, Creative Commons.

Longleaf pine stand in the Croatan National Forest, North Carolina. Photo by David McAdoo, Creative Commons.

Longleaf pine trees once rose to the sky on more than 90 million acres across the Southeast, towering over grasses and flowers and providing habitat for many animals that are now rare. Less than 3 million acres of these forests remain, but returning degraded ecosystems to longleaf pine forests is a priority for many managers and organizations.

U.S. Forest Service scientist Joan Walker and her colleagues developed a roadmap for restoring these forests, especially the understory plant communities. Walker, a plant ecologist at the Forest Service Southern Research Station Restoring Longleaf Pine Ecosystems unit, co-authored a study that quantified and evaluated a reference model for use in restoring southeastern U.S. longleaf pine woodland understory plant communities. The study was led by Lars Brudvig, a professor at Michigan State University, and published in an article in PLoS ONE.

Walker and her colleagues developed and quantified local and regional models of longleaf pine ecosystems. The models used information from 232 longleaf pine woodland sites in longleaf pine’s historical range. There were three study areas – Fort Bragg, North Carolina; Fort Stewart, Georgia; and the Savannah River Site, South Carolina. The models showed how previous land use, fire frequency, and canopy overstory affected grasses and flowers on the forest floor.  The scientists found that all the suspected degradation factors were important, but the effects varied among the study locations.

In the regional model, fire frequency and land use history were the most important factors affecting longleaf pine forests and their understory herbaceous communities. Like much of the longleaf pine region, the study locations were historically fragmented by agriculture. Areas with a history of agricultural use and low fire frequency were the most degraded, while historically forested sites were more similar to each other, and to the reference sites. The importance of land use legacies is becoming clear, and the study shows that multiple drivers of ecosystem degradation – including land use histories – can be quantitatively incorporated into ecological reference models.

The researchers also developed location-specific models for each study area, and found that there were many variations between regional and local models. For the Savannah River Site, the three main factors affecting understory communities were the same identified in the regional model – fire, land use history, and the size of trees – although the importance of each factor differed. The other two sites differed even more from the regional model. On Fort Bragg, land use history explained all the changes in understory plant communities, while on Fort Stewart, soil characteristics were the most important factor.

The remaining challenge is to determine how to best restore longleaf pine understory communities once patterns of degradation have been assessed. Based on the model, thinning overstory trees in some areas may promote understory diversity, while replanting native understory species may be more helpful in others. Wiregrass is one of the species that may need to be replanted in some areas, and Walker and her colleagues at Clemson University are currently growing wiregrass in common gardens. The grass will eventually be used in restoration efforts and future studies.

The model lets managers broadly infer the degradation status of longleaf pine understory communities in the study region. Additionally, since the information used to construct the models is often readily available, the framework can be used to develop local reference models for other areas. This flexibility means the approach can also be applicable to degraded ecosystems across the globe, since information about other suspected drivers of ecosystem degradation can be added to the model.

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For more information, email Joan Walker at

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