Windbreak Renovation Techniques

Joe Zeleznik

NDSU Extension Forester

The first phase of a windbreak thinning project was recently completed at the Carrington Research Extension Center. The single-row field windbreak is about 150 yards long and was planted in the 1960’s with golden willow. The trees are approximately 40 feet tall and were overhanging into the nearby fields, disrupting planting, tillage and harvesting operations. There was a thick understory consisting of chokecherry, boxelder, green ash, red-osier dogwood and honeysuckle. Many dead and broken trees were cluttering the stand. The NDSU Extension Forester began a project to clean up the windbreak, beginning the process of regenerating the willow trees and allowing easier access to the adjacent fields.

The thinning was completed in late April and early May 2004, just as the trees were showing leaves and flowers. The majority of understory trees and shrubs and most of the standing dead trees were cut. Any stems or large branches leaning far out into the fields were cut. This reduced the windbreak density substantially.

Because of the clumped growth habit of willow, some of the remaining trees had as many as five individual stems remaining. In those spots, one or two of the live trees were harvested with the goal of encouraging sprouting from the stumps and roots. Felling and pruning the trees took approximately 17 hours of labor. The slash (cut tops and stems) was chipped right back into the windbreak. These chips will act as a mulch, increasing available soil moisture for the remaining trees and keeping out weeds. As the chips decay, they will add organic matter back into the soil, allowing further moisture retention and encouraging nutrient cycling.

The windbreak will be monitored for the next few years for regrowth. Ideally, the cut trees will begin to sprout from the stumps or roots. As these new trees become established, the overstory trees will be thinned again, encouraging more sprouting and further creation of the next stand of trees. Once regeneration is firmly established, then the final overstory trees will be removed. This process will take as many as 5-10 years for completion. However, following these methods, we hope to regenerate a new stand of trees while still keeping protection for the adjacent fields and roads.

This collaborative project presents a variety of benefits. Because thinning and establishing natural regeneration are not common practices in North Dakota windbreaks, this venture offers a great opportunity to demonstrate two powerful renovation techniques. For the Carrington REC, it allows much easier access to fields and a healthier windbreak.