Science for productive forests: Advancing silvicultural understanding and operations
Forest Service researchers have supported the agency’s multiple use mandate since the early 1900s. Our long-term research studies and sites provide the essential underpinnings for silviculture nationwide. Our scientists support national forest and grassland managers as they develop complex land management plans that address the agency’s multiple use-sustained yield mandate.
Authorized by Congress and designated by the Chief of the Forest Service, experimental forests and ranges host long-term studies over many decades. The Agency established our first experimental forest, the Fort Valley Experimental Forest, in 1908 near Flagstaff, Arizona. Today, agency researchers manage 84 experimental forests and ranges. Studies from these locations have produced crucial insights that have improved silviculture practices.
The National Land Cover Database and its Tree Canopy Cover dataset, i-Tree Landscape tool, and TreeMap tree-level model leverage Forest Inventory and Analysis ground data to give detailed spatial information on forests. The suite of tools helps managers estimate and project forest cover, mortality, and health.
Additionally, our researchers are exploring the use of artificial intelligence and advanced statistics to assess tree growth rates, future yields, and mortality for tropical hardwoods like mahogany in the U.S. territories. Soil information from science-based tools enables managers to decide which tree species to manage, select silvicultural methods, and plan timber harvests.
The Resources Planning Act Assessment modeling framework allows managers to compare long-term implications of different management approaches on future forest attributes including removal and mortality volumes, planted area, area by forest type, and shifts in volume by diameter class and species.
Our researchers are also educators: they teach courses for the National Advanced Silviculture Program and participate in events like the Biennial Southern Silviculture Conference to share research and train the next generation of foresters.
In support of forest planning, this Forest Vegetation Simulator-compatible tool integrates databases, growth and yield models, wildlife models, geographic information systems, and visualization tools to model current and future forest trends. The Tribal Connections Viewer allows forest staff to quickly look up local and regional Tribes for consultation on forest management.
Improving Species-Specific Sustainable Management
Forest Service researchers work at multiple scales—sometimes the work is global or national, other times it is at the ecosystem level. Our scientists also work at the scale of individual species in support of active forest management. Creating knowledge and tools across these scales ensures that, per the Organic Act that founded the Forest Service, we “improve and protect forests, secure favorable conditions for water flows, and provide a continuous supply of timber.”
As domestic and foreign oak demand increases, our knowledge about oak management, published in a series of guides, helps landowners apply advances in silviculture and prescribed fire to ensure a sustainable and productive supply of white oak the trees used to create barrels for Kentucky’s $9 billion bourbon industry. A new subregional timber supply modeling tool examines ten different species of hardwood, allowing researchers to account for species-specific market and forestry trends and access vital insights for industries that rely on white oak.
Fast-growing white pine were once the largest cash crop in the northern Rockies, but a combination of blister rust fungus, beetles, and logging severely reduced its range during the 20th century. New agency guidelines for regenerating and establishing white pine are updated with the latest science-recommend practices such as encouraging forest openings and visible sky. Managers on the Idaho Panhandle National Forests are already working with agency researchers to realize these practices. Together, they are showing partners places where bigger canopy openings will help to reestablish white pine over large landscapes.
In the past, managers aimed to increase vigor and decrease mortality of white pine by radial thinning—clearing openings around individual trees. By working with white pine managers from the Umpqua National Forest and the Bureau of Land Management, Forest Service scientists found that radial thinning is less beneficial for promoting white pine than originally hoped, demonstrating the importance of long-term monitoring and learning from landscape-scale treatments.
The native loblolly pine is widely grown in intensive monoculture stands and is a key species for timber products. Our research informs the efficient and effective management of this important timber species. For example, we published a guide to seed transfer throughout the eastern U.S., and we have investigated drivers of productivity in planted loblolly stands.
For the last 70 years in Wisconsin, our scientists have monitored the effects of various forest cutting methods for hardwoods, concluding that single-tree selection methods yield the most economic and forest growth benefits. Similarly, researchers comparing silviculture systems used over the past 65 years in mixed northern conifer stands in Maine developed strategies to promote tree quality and value.
Our research shows that uneven-aged group selection harvesting for wood products can offset hazardous fuels reduction costs while restoring fire-resistant pine species. Researchers have also demonstrated that modified group selection harvest can improve the growth, vigor, and mortality of fire-resistant ponderosa pine.
Enhancing Forest Operations
Forest Service science sets the standard for forest operations and harvest, from traditional timber sales to salvage logging to biomass removal for fuels treatments. Forest Service researchers have developed innovations in forest operations that improve harvest outcomes and lower the costs of fuels and salvage management.
Agency scientists are replacing outdated harvest models with ones informed by LiDAR, GIS, and other technologies. For example, we have updated strategies for carrying out operations on steep slopes, making more places accessible for mechanical treatments by using tools like tethered logging. Our researchers are also helping mill operators optimize the amount of lumber they can produce from logs using the Log Recovery Analysis Tool.
Agency scientists mapped the suitability of different harvest systems across the Nez Perce-Clearwater National Forests. By combining LiDAR and ground plot inventory data with engineering information, our scientists helped forest managers determine optimal ways to deploy harvest systems, including tethered and winch-assisted equipment—approaches suitable for many national forests.
Our researchers also have reported how changing winter conditions may affect timber harvest. Winter timber harvest is common in many areas, as snowpack and frozen ground mean operations may have less of an environmental impact.
Additionally, long-term agency research shows that canopy gaps created by disturbances help northern California forests thrive. While a lack of fire and prolonged drought has decreased gap abundance in recent decades, responsible logging—alongside other controlled and natural disturbances—may help to restore healthy forest structures.
