By Dan Eskelson
A properly designed windbreak has a profound effect on the physical and economic well-being of both humans and animals. Research has shown that heating costs can be reduced by up to 40 percent, since reduced wind velocity results in reduced air infiltration in homes and outbuildings. The shelter created by a windbreak provides a safer and more pleasant outdoor work and play area.
A five year study in Iowa indicated that cattle sheltered from the wind gained an average of 80 pounds more per year and consumed 129 pounds less feed per hundredweight of gain than cattle not sheltered. Other animals, including game, find food and habitat within the windbreak, especially if diverse species of plants are used. Windbreaks also block blowing and drifting snow, reduce soil erosion and provide a pleasant visual barrier throughout the year.
Strategies and techniques used in the creation of windbreaks vary depending on site specific conditions and the owner’s requirements. Given adequate resources and sufficient area, a multi-row windbreak with a lot of plant diversity is ideal (see Fig. 1). Rows should extend well beyond the width of the area to be sheltered, and spacing between rows should account for mature plant width and maintenance practice between rows.
Placement of the windbreak should allow for the blockage of the most severe winter winds; in much of the country this would be to the north or northwest of the homestead. In areas where troublesome winds come from more than one direction, the windbreak can be planted in a “V” or “L” shape. Recommendations for the distance from windbreak to homestead (“D” in Fig. 2) vary from state to state, but average from five to seven times the height of the tallest mature trees. That distance should be measured from the row of tallest evergreen trees to the center of the protected area.
So if the tallest trees reach 30 feet at maturity, distance would be 150 to 210 feet. Though the five row system will provide very efficient shelter, even a one row windbreak will provide significant benefit. If limited to just one row, evergreen trees should be specified. In the northern Plains states, however, windbreaks should be planted with five or more rows to block the extreme high winds and blowing snow.
Though it is best if no roads or work trails penetrate a windbreak, if absolutely necessary these paths should proceed through at an angle rather than parallel to the wind direction. Even at an angle, a path is susceptible to heavy snow buildup, and if close to parallel to the wind direction, the path will allow a funnel of strong wind to penetrate.
Diversity of species, even within the row, is important both from cultural and aesthetic perspectives. Culturally, diversity will provide some level of insurance if one species comes under attack from insect or disease. Aesthetically, diversity provides more interest in the landscape, especially during long, visually bleak winter months. In addition to the above, diversity in plant selection can provide food and habitat for a wide variety of birds and animals. Plant selection should be made with full knowledge of soil types, which may vary even within the site.
Two rows of evergreens, of different height as indicated in Fig. 1, will provide better protection than one row, and each additional row will contribute to further improvement of the windbreak. Though exact choice of plants should be made on a site-specific basis, at least some of the following suggestions will work for most sites. Consult with local soil conservation or county extension agents for plant suggestions based on specific soil type, hardiness zone, topography, exposure, etc.
Windbreaks Rows 1 and 5
Highbush Cranberry, Forsythia, Spirea, Honeysuckle, Barberry, Privet, Sumac, Redtwig Dogwood, Lilac, Currant, Chokecherry, Winterberry, American Plum, Caragana
Windbreaks Row 2
Redcedar, Arborvitae, Rocky Mountain Juniper, Serbian Spruce, Dwarf Blue Spruce, Jack Pine
Windbreaks Row 3
White Pine, Douglas Fir, Norway Spruce, Shortleaf Pine, Austrian Pine, Red Pine, White Fir, Concolor Fir, Ponderosa Pine
Windbreaks Row 4
Pin Oak, Honeylocust, Hackberry, Red Oak, Black Walnut, Black Locust, Beech, Russian Olive, Siberian Elm, Silver Maple, Green Ash
Note that in a multi-row system the evergreens should be on the windward side of the deciduous trees, and the best wind deflection occurs with a rising plant height as shown in Fig. 1. Aside from the aesthetic and wildlife food values of the small shrub rows, these faster growing plants will provide some measure of wind and snow protection long before the slower growing trees.
In addition to the above mentioned benefits of windbreaks, wise tree placement can also provide energy savings and greater creature comforts in summer months. As shown in Fig. 2, trees can be used to funnel summer breezes toward living areas; both evergreen and deciduous trees will serve this function, but for aesthetic purpose a combination of both may provide the best design solution.
The establishment of a windbreak is undoubtedly a major investment, but considering the long term economic, aesthetic and social returns, it is an investment that will benefit several generations.