NAC | Working Trees for Carbon: Windbreaks in the U.S.

Working Trees for Carbon:
Windbreaks in the U.S.

Windbreaks are used throughout the U.S. to accomplish a multitude of objectives. Among these are the reduction of crop water stress to improve yield and quality, reduction of soil erosion, snow management, livestock protection, odor control, wildlife habitat provisions, and energy conservation around farmsteads.

If society is looking for places to store carbon, windbreaks are an obvious choice. Since a large number of landowners already appreciate the value of a windbreak for the many benefits listed above, many are interested in discussing ways to get financial assistance for planting and maintaining a windbreak that was also designed to optimize carbon storage. The simple fact that many landowners are motivated to establish windbreaks for their own purposes, suggests that these plantings would remain in place for a long time. Due to the extensive agricultural land base, especially in the North Central U.S., large amounts of carbon can be stored by integrating more windbreak plantings into the agricultural landscape.

The following scenarios describe the potential for carbon storage in tree stems over a 20-year period. Roots are not included, but would likely add from 15 to 25 percent to the totals. In addition, windbreaks typically function effectively for 50 to 70 years and would continue to accumulate carbon over the life of the planting.

Field Windbreaks
Field windbreaks reduce evaporation and plant transpiration rates such that crop yields in a field are typically increased, even though a portion of the field has been converted to windbreaks. Research has estimated the optimal tree planting levels at between three and six percent of the cropped field area. There are 210 million cares of cropland unprotected by windbreaks in the North Central U.S. and of this, 30 million acreas are subjected to wind erosion in excess of the soil loss tolerance rate. Each million acreas of planted windbreak would respresent 200 million trees storing 21.2 metric tons fof carbon dioxide (CO₂) at age 20.

Within 20 years field windbreak storage could
exceed 215 million metric tons of CO₂

In addition to carbon stored in windbreak trees, the protection provided by the windbreak results in energy savings from reduced fuel use. In the case of field windbreaks, land removed from agricultural production results in less fuel use. Based on average of five gallons of diesel fuel per acre for most crops, planting 60,000 acres to windbreaks would reduce fuel consumption by 300,000 gallons annually.

Protecting the 210 million acres of exposed cropland in the North Central U.S. by planting five percent of the field area to windbreaks would sequester over 215 million metric tons of CO₂ in the first 20 years.

Farmstead Windbreaks
Of the more than 800,000 farms in the North Central U.S., over 300,000 have no wind protection. For farmsteads in cold climates, windbreaks have been shown to reduce home heating requirements by 10 to 20 percent. Assuming an averae home uses 2,350 gallons of propane per heating season, a 15 percent savings would reduced annual demand by 10.6 million gallons. While this benefit would not begin until the windbreak reached an effective height (about 10 years) it would continue throughout the remaining life of the windbreak, typically 40 to 50 years. Over this period fuel savings in excess of 290 million gallons could be expected.

Planting windbreaks around these 300,000 unprotected farms would result in
120 million trees (approximately 400 trees per home) storing
13 million metric tons of CO₂ within 20 years.

Living Snowfences
In North Dakota, South Dakota, Nebraska, Minnesota, and Iowa there are over 460,000 miles of roadway. Many of these would benefit from protection with a living snowfence. Properly designed living snowfences can dramatically reduce the need to plow and re-plow roadways. Assuming a 1/3 reduction in snow removal costs, fuel usage for every 1,000 miles of protected roads could be reduced by 320,000 gallons annually.

For each 1,000 miles of roads protected by windbreaks two million conifers
could be planted to store 175,000 metric tons of CO₂ within 20 years.

References

Adapted from "Opportunities to increase Tree Planting in Shelterbelts and the Potential Impcats on Carbon Storage and Conservation," Brandle, James; Wardle,Tom; and Bratton, gerald. Chapter 9, Forests and Global Change, Vol. 1 Edited by Sampson, R. Neil; and Hair, Dwight; American Forests, 1992.

The USDA National Agroforestry Center (NAC) is a partnership of the USDA Forest Service, Research & Development (R&D)(Rocky Mountain Research Station) and State & Private Forestry (S&PF) and the USDA Natural Resources Conservation Service. The Center's purpose is to accelerate the development and application of agroforestry technologies to attain more economically, environmentally, and socially sustainable land-use systems. To accomplish its mission, the Center interacts with a national network of cooperators to conduct research, develop technologies and tools, establish demonstrations, and provide useful information to natural resources professionals.

Contact Information: USDA National Agroforestry Center, East Campus-UNL, Lincoln, Nebraska 68583-0822. Phone: 402-437-5178. Web site:www.unl.edu/nac.

Last updated 03.07.2000.
Contact us.