Iowa needs a Windbreak Renaissance!
The Iowa wind never ceases to impress me! My recent travels across the state have made one thing clear – Iowa is in desperate need of a windbreak renaissance. Windbreaks and shelterbelts act as critical farm infrastructure – providing energy savings, livestock growth gains, timber and non-timber forest products, wildlife habitat, odor and dust control, aesthetics, and privacy. However, Iowa’s aging windbreaks are simply not functioning as they should be, due to general decline, storm damage, and insect and disease issues. Also, I “see” non-existent windbreaks in locations where they could have incredible value. To help guide recovery and resilience, consider the following tips for three common windbreak scenarios.
Scenario 1: Spotty/isolated decline or damage
Here, start by assessing the status of individual impacted trees. Snapped or split stems and/or loss of >50% of the canopy may warrant removal. Consider, however, that interplanting or replacement of individual trees will be tough, as most Iowa windbreak species (especially conifers) are shade-intolerant (i.e., they don’t grow well in shade). Assess the size and spacing of the residual trees and gaps, and ask yourself whether neighboring trees have capacity to fill the voids. If so, removal of damaged trees and proper pruning of residuals to prevent disease and decay may be the best strategy.
Scenario 2: Large gaps, row additions needed
If large gaps exist (or will be, following removals), functionality is severely compromised (Photo 1). In this scenario, neighboring trees will not be able to fill gaps, and it’s time to consider adding new rows. Number of row additions will depend on current windbreak design and your objectives. Often, folks decide to keep residual large trees for aesthetics and structural diversity, then remove once new rows have attained functional height and crown closure.
Photo 1. Growth from residual trees will be unable to fill large gaps such as this. Situations such as these may warrant addition of new rows to restore functionality. Photo credit Mark Vitosh, IDNR.
Scenario 3: Complete replant/establishment of new windbreak
In many cases, damage or decline is so severe that starting over from scratch is required. Design (e.g., number of rows, spacing) and species selection will depend heavily on your site conditions and objectives, thus no cookbook recipe exists. However, it is essential to match species to soil and site conditions. Selecting the right species will encourage a long-lived, vigorous, and functional windbreak. Second, go for species diversity! Windbreaks comprised of one or two species are more vulnerable to insects, disease, storms, and other stressors. Monocultural planting of non-native blue, white, and Black Hills spruce, for example, has led to widespread loss of functionality within Iowa windbreaks (Photo 2). Selecting conifers for Iowa windbreaks is tough, as our state has only a handful of native evergreens. Conifers that perform best in Iowa windbreaks include: eastern redcedar and white pine (both native to Iowa), and northern white cedar, Norway spruce, and white fir (all non-native to Iowa, but hardy).
Photo 2. Non-native spruce in severe decline due to needle cast fungus. Non-native conifers like blue, white, and Black Hills spruce, frequently exhibit low vigor and are prone to disease issues. Photo credit ISU Plant and Insect Diagnostic Clinic (PIDC).
Lastly, consider wildlife and pollinators during your design and species selection. Incorporating rows of native shrubs and hardwood trees with varying mature sizes will add critical structural diversity, cover, and food to benefit a range of species. In working landscapes, windbreaks often represent invaluable oases of critical habitat.
Timing and Resources
As spring is the recommended season to establish conifers, late summer through winter is the prime planning period for windbreak renovation and establishment. Natural Resources Conservation Service (NRCS) staff provide windbreak renovation and establishment technical service, and should be an initial point of contact. Cost share programs exist as well, notably the Environmental Quality Incentives Program (EQIP) and the Resource Enhancement and Protection (REAP) program. Professional foresters with the Iowa Department of Natural Resources, as well as private forestry consultants, are other valuable resources. Get with these pros and start the renaissance!
Four “Windbreak School” programs will be held in-person across the state this winter - three Crop Advantage Series events: Ankeny (1/12), Cedar Falls (1/13), and Atlantic (1/20), and a more in-depth workshop in Tama County on 2/8 (free event, open to all). If unable to attend in person, watch for the forthcoming CropsTV! “Windbreak School” webinar that will be available in late winter on our archived video page. Check the “Upcoming Forestry Events” page on the ISU Extension Forestry website for details on this series, and other Extension Forestry events.