Forest Stand Improvement (NRCS #666)

Applicable Systems

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About

Forest stand improvement, sometimes referred to as timber stand improvement, is the practice of altering the species composition, structure, or density of a tree stand to enhance its function¹ ². Forest stand improvement uses silvicultural techniques, such as thinning, harvesting, planting, and prescribed burning to meet desired goals while considering site characteristics. Additionally, land managers should identify crop trees, or the trees intended for future harvest, and choose management strategies that improve the selected crop trees. Generally, forest stand improvement techniques promote a healthy, productive, and biodiverse forest system.

Key aspects and considerations:

Identify desired species.
Determine optimal spacing and density.
Remove invasive species.
Minimize unintended negative impacts.

Benefits and Limitations

ACRE Category	Benefits	Limitations
Soil Health	Maintaining inputs, such as decomposing wood, can increase litter and organic matter cycling. Can help reduce soil erosion by increasing species diversity and promoting understory growth. Increases soil biological activity and nutrient cycling.	Thinning may decrease litterfall stocks³. Disturbance from harvesting or mechanical management may expose soil temporarily. Soil may be vulnerable to compaction depending on equipment use and timing of tree harvest.
Water Management	May reduce runoff and increase infiltration by increasing species diversity and maintaining roots and litter. By reducing runoff and soil erosion, forest stand improvement improves water quality of nearby waterways. Healthy forests assist in filtering contaminants. Managing forest stands for a range of tree age classes increases water yield by improving the water balance.	May increase short-term runoff due to temporary soil disturbance from logging and thinning.
Nutrient Management	If leaf litter, needles, and biomass are retained, management may improve nutrient cycling. Reduces nutrient loss through erosion control.	N/A
Agricultural Production	Improves tree and understory health. Reduces competition and increases tree growth. Improves timber quality and growth rates of residual trees. Thinning improves drought tolerance⁴. Increases resilience to pests and diseases. Reduces losses from mortality, diseases, overcrowding and wildfires.	N/A
Biodiversity and Wildlife	Improves habitat and food availability, promoting greater wildlife diversity. Altering species composition can reduce invasive species and weeds. Supports understory plant regeneration.	May reduce microhabitat and deadwood availability⁵.
GHG Emission	Improving stand health increases carbon storage above and belowground. Practicing forest regeneration also increases carbon sequestration. Avoiding clear cutting and maintaining trees throughout their lifespan reduces further CO₂ emissions⁶. Supports long-term forest carbon stability.	Disturbed sites may temporarily release stored carbon. Tree thinning reduces carbon stocks³ ⁷, but may increase annual gains in carbon for remaining trees and reduce recovery time⁷. Evaluating changes in forest carbon fluxes requires long-term perspectives.
Economics	Provides income if thinned trees are sold for timber, firewood, or other forest products. Increases stand value and tree quality in the long-term through thinning and management. Land managers may be eligible for cost-share programs through NRCS EQIP or other local and federal programs.	Requires technical expertise and long-term management planning. There are costs associated with planning, labor and equipment for removing unwanted or poor-quality trees and vegetation. Economic returns require a long-term perspective.

Impact on Agricultural Resilience

In the Midwest, forest health is impacted by changes in temperature, precipitation, pests, and invasive species⁷. Northern and boreal forests in the region are likely to be most impacted, as warming temperatures are likely to decrease suitable habitat⁸.
As climate change continues, forest management must consider and respond to these stressors. By implementing forest stand improvement, land managers can reduce the vulnerability of forests to changing environmental conditions. For instance, selecting species that are adapted to higher temperatures and extreme rainfall can increase forest resilience. Additionally, forest stand improvement can increase drought tolerance through improved species selection, thinning, and management.

Regional Applicability

Forest stand improvement can be implemented anywhere there is a forest, woodland, or stand of trees. In the Midwestern U.S., boreal forests are common in the north, while oak-hickory forests dominate in portions of the Ozarks. Forests and forest products contribute substantially to the Midwestern economy; in Wisconsin alone, the industry was found to contribute $27 billion to the economy.
While forest cover is most prominent in the northeast U.S., forest stand improvement can be practiced across the Midwest. For example, recent research in the White River Basin of Indiana suggests forest stand improvement in central hardwood forests can improve timber productivity and increase stand value, though is most profitable with voluntary incentive programs⁹.
Midwest forests will face increased vulnerability due to rising growing-season temperatures, increased frequency of drought, and reduced winter snowpack, a result of ongoing climate change. Forest stand improvement can help land managers effectively manage their land in light of these environmental changes.
According to a USDA report, in 2020, tree release and weed treatments, precommercial thinning, pruning, and fertilization cost $225, $244, $116, and $9 per acre, respectively.

Case Studies

In Virginia, a demonstration woodlot was thinned, with a focus on harvesting over-mature sawtimber and reducing crown competition. The demonstration site highlighted barriers to thinning, as it was challenging to find a timber operator interested in the job due to limited acres.

Resources

University of Tennessee Extension: Forest Stand Improvement in the Eastern U.S.
Missouri Department of Conservation: Missouri Timber Stand Improvement
Wisconsin Department of Natural Resources (DNR): Silviculture Handbook: Intermediate Treatments
University of Minnesota Extension: Thinning and Woodland Stand Improvement
Minnesota Board of Water and Soil Resources: Forest Stand Improvement Training Series
University of Minnesota Extension: Minnesota Climate Ready Trees
Iowa Department of Natural Resources (DNR): Forestry Landowner Assistance
Illinois Department of Natural Resources (DNR): Forest Stand Improvement
University of Illinois Extension: Forestry Resources
Indiana Department of Natural Resources (DNR): Forest Resources in Indiana
USDA-FS: USDA Tree Atlas
USDA-FS: Forest Management
Video. USDA-NRCS: Forest Stand Improvement
USDA-FS and Northern Institute of Applied Climate Science (NIACS): Forest Carbon Management Menu
USDA-FS: Silvicultural Guide for Northern Hardwoods in the Northeast
USDA-NRCS: Forest Management and Forest Stand Improvement Fact Sheet
USDA-NRCS: Forest Stand Improvement Overview
USDA-NRCS: Forest Stand Improvement Standard

References

USDA-NRCS (2022). Conservation Practice Standard Document, Forest Stand Improvement, Code 666. https://www.nrcs.usda.gov/sites/default/files/2022-11/666-NHCP-CPS-Forest-Stand-Improvement-2022.pdf
USDA-NRCS (2022). Conservation Practice Overview, Forest Stand Improvement, Code 666. https://www.nrcs.usda.gov/sites/default/files/2022-11/666-NHCP-PO-Forest-Stand-Improvement-2022.pdf
Zhang, H., Liu, S., Yu, J., Li, J., Shangguan, Z., & Deng, L. (2024). Thinning increases forest ecosystem carbon stocks. Forest Ecology and Management, 555, 121702.
D'Amato, A. W., Bradford, J. B., Fraver, S., & Palik, B. J. (2013). Effects of thinning on drought vulnerability and climate response in north temperate forest ecosystems. Ecological Applications, 23(8), 1735-1742.
Dieler, J., Uhl, E., Biber, P., Müller, J., Rötzer, T., & Pretzsch, H. (2017). Effect of forest stand management on species composition, structural diversity, and productivity in the temperate zone of Europe. European Journal of Forest Research, 136(4), 739-766.
Janowiak, M., Connelly, W. J., Dante-Wood, K., Domke, G. M., Giardina, C., Kayler, Z., et al. (2017). Considering forest and grassland carbon in land management. General Technical Report, Washington Office, 95.
Ontl, T. A., Janowiak, M. K., Swanston, C. W., Daley, J., Handler, S., Cornett, M., et al. (2020). Forest management for carbon sequestration and climate adaptation. Journal of Forestry, 118(1), 86-101.
Swanston, C., Brandt, L. A., Janowiak, M. K., Handler, S. D., Butler-Leopold, P., Iverson, L., et al. (2018). Vulnerability of forests of the Midwest and Northeast United States to climate change. Climatic Change, 146(1), 103-116.
Wang, Y., Ma, W., Farlee, L. D., Jackson, E. A., Shao, G., Ochuodho, T., et al. (2021). Assessing the benefits and economic feasibility of stand improvement for central hardwood forests. Forest Science, 67(3), 297-311.

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Forest Stand Improvement photo 1 — Photo 1: Blodgett Experimental Forest in California following mechanical thinning nine years prior.

Photo provided by USDA-FS.

Forest Stand Improvement photo 2 — Photo 2: Stanislaus-Tuolumne Experimental Forest in California, following thinning and a prescribed burn nearly a decade earlier.

Photo provided by USDA-FS.