Last month, we talked about how to establish a windbreak, but what about restoring or replacing an existing windbreak?

Windbreaks may need renovation and/or replacement for a number of reasons. They may be damaged or destroyed due to extreme weather (i.e., tornadoes, straight winds, heavy ice or wet snow), or the trees and shrubs in an existing windbreak may be reaching their normal life span, and need to be removed and replaced with younger plants.

If storm damage is the culprit, here are some simple but important steps to take:

1. Assess the damage. Does the windbreak need cleaning up and light pruning, or are the trees heavily damaged and not salvageable? Focus on individual trees. Some may have fared better than you think. If there is less than a third (33%) crown damage, the tree may recover. Also, look for tree root failure evidenced by raised mounds of soil.

2. Remove downed material. Clearing away debris will give you a better picture of windbreak condition. Watch for hanging limbs and trees lodged in other trees. These can be very dangerous, and could cause injury or even death if they were to fall the wrong way. Be sure to remove hazardous trees next to buildings, machinery or livestock areas.

3. Consider replacement or restoration. If total replacement is required, this is a good time to reassess the windbreak in terms of location, function and species diversity. You might even consider relocating or enlarging the windbreak. Is the windbreak for protection, or is wildlife habitat, erosion control, farmstead and livestock protection, or snow distribution important? Different objectives call for different planning and windbreak designs.

If restoration is in order, examine how much density or amount of solid material is present, along with the arrangement of solid material. Plant diversity, size and growth rate are very important. Combinations of hardwoods, evergreens and low-growing shrubs can provide the right combination for effective windbreak function, density and longevity.

If the existing windbreak plants are stagnant due to tight spacing, thinning of individual trees or rows may be appropriate. Candidates for removal include stunted, overtopped and poorly formed trees, hazards, and dead trees. If you are encouraging woodpeckers or cavity-nesting birds, you may want to leave a dead tree or two.

Aggressive sod-forming grasses (i.e., smooth brome, Kentucky bluegrass, quack grass) compete with woody plants for water and nutrients. If 50% or more of the understory is grasses, then weed control may be required.

Windbreak restoration is an important conservation measure, and assistance may be available. Most conservation programs only cover costs incurred after the request and not activities taken prior to application for assistance.

Be sure to consult with local experts for advice. Regardless of the design, remember you are planning for decades of growth and benefits from your windbreak, so plan carefully.

Miller is a horticulture professor at Joliet Junior College in Joliet, and a senior research scientist in entomology at The Morton Arboretum in Lisle. Email your tree questions to him at [email protected].