Windbreaks are plantings of trees, shrubs or a combination of the two, that reduce wind speed in an agricultural area. They can:
- Reduce energy costs around farmsteads.
- Mitigate livestock odors.
- Reduce wind stress on crops and livestock.
- Manage snow.
- Provide wildlife habitat and timber products.
What are windbreaks?
- Windbreaks integrate woody plants and crops for greater and more diversified use of resources.
- Both the woody and crop components of windbreaks can provide economic benefits.
- Purposes of windbreaks include: wind protection, controlling blowing and drifting snow, wildlife habitat establishment, energy saving, living screens, odor abatement and more.
Windbreaks are plantings of single or multiple rows of trees or shrubs that are established for one or more environmental purposes. They gained popularity in America during the droughts and soil erosion of the Dust Bowl in the 1930s. Projects, such as those by the Civilian Conservation Corps, planted windbreaks to reduce soil erosion on farmland.
The effectiveness of a windbreak depends on suitable tree and shrub selection as well as planting density and spacing. We've provided information on tree and shrub species to consider in Minnesota windbreak plantings and a list of resources for technical and financial assistance.
Benefits and challenges of planting windbreaks
Reduce energy costs around farmsteads
- Planting windbreaks around rural homes and farmsteads can reduce energy costs from heating and cooling.
- On average, well-designed windbreaks have reduced energy costs for rural homes in the northern U.S. and Canada by 10 to 20 percent.
Reduce odors around livestock operations
- Windbreaks can intercept and disperse odors before they accumulate and become a nuisance downwind of a livestock operation.
- Studies have shown that windbreaks can reduce downwind odor concentration by 6 to 33 percent.
Reduce wind stress on crops and improve growing conditions
- Wind can physically damage plants through abrasion and leaf tearing, which can hinder plant growth. By reducing wind speed, windbreaks can reduce this damage to downwind crops.
- Reduced wind speed in the lee of a windbreak can also increase humidity as well as air and soil temperatures for crops.
- Studies have indicated that these favorable growing conditions were, on average, associated with a 6 to 44 percent increase in crop yield.
Protect livestock from wind stress
- Like crops, microclimate conditions for livestock grazing can also be improved by windbreaks.
- Studies have shown that livestock tend to prefer grazing areas sheltered by windbreaks over open areas during cold and windy conditions.
Manage snow around roads and farmsteads.
- Blowing and drifting snow on roadways pose considerable costs to transportation industries and risks to motorists.
- Living snow fences — windbreaks planted next to roads to trap upwind blowing snow — are a cost-effective solution to reducing snow removal costs and preventing accidents.
- Well-designed living snow fences around farmsteads can reduce snow removal time and hassle, as well.
Manage snow on croplands
- Moisture from snow can be an important water resource for crop production in northern, semiarid areas.
- As much as one-third of the snowfall in these areas can be blown off open fields or lost to the atmosphere via sublimation (solid snow particles to water vapor).
- Windbreaks planted to trap snow on fields can add to soil moisture in the spring. Studies have shown this effect to increase crop yields by 15 to 20 percent.
The Minnesota Department of Transportation has a living snow fence program and guidelines for farmers and landowners.
Ecosystem services are benefits humans receive from ecosystems, such as clean air and water. Ecosystem services provided by windbreaks include reducing wind erosion on farmland, which benefits soil fertility, structure and moisture.
Windbreaks also sequester carbon dioxide from the atmosphere into their woody biomass above and below the ground. This can play a role in reducing rising atmospheric carbon dioxide concentrations, as well as adding carbon — an important component of soil fertility and structure — to the soil via leaf and root litter from trees and shrubs.
Wildlife is another benefit of windbreaks. Windbreaks can often provide structural habitat for birds and insects, some of which may be valuable for the control of crop pests. They can also attract game species such as pheasants and quail and improve hunting opportunities.
- Windbreaks planted with valuable timber species can be harvested in the future and provide the farmer with additional income.
- Wood from the windbreaks can also be harvested for building material or firewood.
- Increasingly, fast-growing shrubs and trees, such as willows and poplars, are being considered for sources of biofuels from woody biomass. If these are incorporated into windbreak plantings, they could be harvested on short rotations and sold to a bioenergy facility.
- Lastly, windbreaks can provide economic outputs in the form of fruits and nuts or floral products.
Windbreaks need to be maintained for weeds and moisture in the first years of establishment.
Proper site preparation, which may include application of pre-emergent herbicides or mulch, can reduce the amount of time and effort spent on these issues.
Windbreaks may also compete with crops in their direct vicinity for water, soil nutrients and light.
- To reduce competition, select trees that grow deeper roots than crops or prune roots of trees and shrubs.
- In some cases, loss in crop yields near windbreaks can increase crop yields farther downwind of the windbreak due to improved microclimate conditions.
Effectiveness of a windbreak depends on how well it is designed. Height, density and length are the three main design elements to consider for any windbreak.
When wind encounters a windbreak, some of it goes through the windbreak while some of it travels up and over the windbreak. How far wind has to travel up and over the windbreak is one component in determining the zone of reduced wind speed downwind of the windbreak.
This zone of reduced wind speed is typically defined as a length in reference to the windbreak's height, denoted by the letter H.
- As a rule of thumb, windbreaks typically reduce downwind wind speed for a length of 10H to 30H.
- For example, a windbreak with a height of 10 feet will reduce downwind wind speed for a distance of 100 to 300 feet.
- Windbreaks will also offer some distance of reduced upwind wind speed.
- This typically extends to a distance of 2H to 5H upwind.
Windbreak density controls how much wind goes through a windbreak. One way to observe windbreak density is to face the windbreak perpendicularly and look through it. The harder it is to see through it, the denser it is.
Different levels of windbreak density are used for different purposes.
- For example, when managing snow for crop moisture, windbreaks that are less dense will distribute snow over a greater downwind length than windbreaks with higher densities.
- Higher densities can be helpful for living snow fences.
- Highway right-of-ways have a limited width and require short and deep snow drifts downwind of a fence.
- The desired density of a windbreak will influence the species of plants used and their spacing in a windbreak.
- For example, spruce planted at a close spacing will provide a very dense windbreak, whereas poplar planted at a wide spacing will be less dense.
In addition to passing through and over a windbreak, wind also travels around a windbreak.
Because of this, the length of the windbreak should be oriented perpendicular to the prevailing wind direction for maximum wind reduction. The more closely a windbreak is oriented to the prevailing wind direction, the more easily wind will flow around the windbreak and reduce the zone of protection.
Since wind flows around the ends of a windbreak, the length of the windbreak should be at least ten times as long as its height (10H) to reduce this end effect.
This end effect can be particularly pronounced for living snow fences.
- Living snow fences should have a length of at least 25H.
- Snow fences with lengths less than 25H will have rounded drifts at their ends, extending in about 12H.
Selecting trees and shrubs for windbreaks
Choosing trees and shrubs is extremely important to make sure a windbreak is effective and long-lasting. Plants need to be winter hardy and should have a positive history of plantings in the area suitable for the site and soils.
Select several different species of trees and shrubs, so if there is a failure in a row, the windbreak is still effective. We recommend a mix of deciduous and coniferous plants based on the purpose of the planting.
Many plants can offer potential income benefits such as edible fruits and nuts, materials for decorative crafts, and specialty woods.
Consult with area or county Soil and Water Conservation Districts or National Resources Conservation Service, Department of Natural Resources and Extension staff to get a recommended list of plants suitable for your area.
See Selecting trees and shrubs for windbreaks for recommendations on specific plants hardy to Minnesota.
Brandle, J.R., Hodges, L., Tyndall, J., & Sudmeyer, R.A. (2009). Windbreak practices. In: Garett, H.E. (ed.) North American agroforestry: an integrated science and practice, 2nd ed. American Society of Agronomy, pp 75-104.
Brandle, J.R., Hodges, L., Zhou, X.H. (2004). Windbreaks in North American agricultural systems. Agroforestry Systems 61-62:65-78.
Gullickson, D., Josiah, S.J., Flynn, P. (1999). Catching the snow with living snow fences. University of Minnesota Extension, St. Paul, MN.
Johnson, R.J., Beck, M.M., Brandle, J.R. Windbreaks and wildlife. University of Nebraska Extension EC 91-1771-B.
Streed, E., Walton, J. (2001). Producing marketable products from living snow fences. University of Minnesota Extension, St. Paul, MN.
Reviewed in 2020