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Talking all things horticulture, ecology, and design.
Welcome to the Good Growing Podcast. I am Emily Swihart, horticulture educator with the University of Illinois Extension, coming to you today from Milan, Illinois with a Gardenbite. On this week's Gardenbite, we are going to talk about a topic that may seem simple and familiar, but contributes to environmental conservation, boosts our economy, and improves the health of communities. Today, we are talking about windbreaks. Traditionally, windbreaks are linear plantings layered with trees and shrubs that protect the land from the often relentless midwestern winds by intercepting the wind and thereby reducing wind speeds.
Emily Swihart:Also known as shelterbelts, windbreaks have the potential to provide expansive benefits, such as creating wildlife habitat, improved biodiversity, soil protection, energy savings, shade, visual screening, and more. Windbreaks are utilized as critical components of agriculture around the world and have been for centuries. But hang on. Communities are not to be left out of our discussion. But first, let's take a look at the origin of windbreaks in the Midwest.
Emily Swihart:In the Midwest, shelter belts hold ecological and historical significance. The landscape was once dominated by native prairies with the occasional woodland, riparian area, and transition zone of a savanna. This was the North American landscape for 1000 of years until European settlers arrived, and the prairie was plowed and soils were exposed to eroding winds. Over time, the problem of wind erosion compounded. By the 19 thirties, it was clear that land management practices needed to change.
Emily Swihart:Dust storms devastated millions of acres of farmland causing environmental and human health problems. In 1934, at the height of the dust bowl, president Franklin Delano Roosevelt included in the new deal resources for the strategic planting of windbreaks on farms, where the reduced wind speeds would also reduce the severe soil erosion and dust storms of the era. Many of us are familiar with the Civilian Conservation Corps or CCC and Works Progress Administration, WPA, as employment programs created through the new deal to help address the severe economic challenges of the 19 thirties. Accomplishments of these programs include creating and expanding the accessibility and accommodations of state and national parks, protecting lands against wildfire, building flood barriers, and planting over 200,000,000 trees throughout the Midwest in the form of windbreaks. From 1935 to 1942, the young men involved in planting trees became known as Roosevelt's Tree Army.
Emily Swihart:And to this day many of these projects remain although many are in need of restoration and rejuvenation so how do wind breaks work? Functioning wind breaks reduce wind speed by intercepting airflow and causing a change in velocity as the wind is interrupted by plant material the air is diverted over around and through the plant material at lower speeds the efficacy of a wind break is influenced by orientation plant height planting length, and continuity. The most effective windbreaks are planted perpendicular to the prevailing winds. In the Midwest, we are generally trying to intercept cold winter winds from the northwest. So windbreaks are typically planted on the north and west sides of a property.
Emily Swihart:Plant height greatly influences how much impact a windbreak will have and is used to predict how far downwind the impact will be felt. The downward side of a windbreak, the area where the wind speeds are reduced, is known as the wind shadow. The extent of this protected area is approximately 10 to 15 times the height of the tallest plant in the windbreak. So the wind shadow of a 30 foot tree may extend up to 450 feet downwind. A 50 foot tall windbreak may produce a wind shadow of up to 750 feet.
Emily Swihart:The length of the planting determines how much land the trees will protect, and having a continuous stretch of the windbreak will minimize the risk of wind tunnels or areas where the wind will be funneled through the narrow opening in the windbreak, creating the potential for an increased velocity. The optimal windbreak design includes multiple rows of plant material of multiple species. 2 or 3 rows of conifers on the windward side, a few rows of deciduous trees on the interior, and a few rows of shrubs on the leeward side is recommended. Traditionally, windbreaks are represented in graphics as a straight row planting along the edge of a property, and this form can be seen throughout the Midwestern landscape. However, groups of trees in any configuration or at any size can provide some level of protection and windbreak benefit.
Emily Swihart:The style of windbreak described here is reminiscent of those found in rural farmsteads, but the benefits of a windbreak can be achieved in an urban environment. Communities that prioritize and manage an urban forest will experience reduced wind speeds. Conifers are most impactful as windbreak species, but a dense canopy of deciduous trees will interrupt wind speeds. Managing an urban forest so that windbreak benefits can be achieved includes planting tree species that will reach a large mature size, providing adequate space and protection for trees so that they will be able to grow large over time, and funding and implementing a maintenance plan that will help promote tree health and vigor. The cumulative impact of trees in an urban environment can act as a windbreak to help reduce winter chill.
Emily Swihart:They also provide the benefits of summer shade, helping to manage stormwater, producing clean air, and creating more livable communities. So whether it's preserving rural land, increasing biodiversity, or enhancing communities for the human inhabitants, windbreaks are powerful tools for resilience and conservation. And I hope as you get outside and enjoy the variety of landscapes available to us throughout Illinois, You will pay a bit more attention to the tall trees at the edge of a farmstead or the large majestic trees that also call our communities home and give them a little thanks for the help that they provide in reducing wind speeds along with all of the other benefits they provide. Well, that's all I've got for you during this week's Gardenbite. The Good Growing Podcast is a production of the University of Illinois Extension.
Emily Swihart:Listeners, thank you for doing what you do best and listening. Or if you're watching on YouTube, watching. And as always, keep on growing.