Prairie Willow Research, I-94 Roadside

Summary

This project aims to evaluate the performance of prairie willow plants in roadside conditions. Prairie willow (Salix humilis) is an underutilized native shrub willow. With a natural ability to grow in diverse environmental conditions, prairie willow appears to be incredibly adaptable. However, this adaptability has never been formally tested. In collaboration with the MnDOT’s Environmental Planning and Design Unit, we have identified a potential project on I-94 near the Franklin Avenue Bridge to supplement a negotiated maintenance contract that MnDOT is currently designing. By establishing a roadside plot of prairie willows, this work will assess whether this plant is capable of tolerating the harsh conditions characteristic of a roadside environment, specifically regarding soil moisture and salt. Prairie willow encompasses two naturally occurring botanical varieties- Salix humilis var. humilis (prairie willow) and Salix humilis var. tristis (dwarf prairie willow). The dwarf variety grows to ~ 3 ft tall at maturity whereas the non-dwarf variety can reach ~ 10 ft in height. Both botanical varieties are quite dense, capable of lateral spread, and can be coppiced/cut back routinely for management purposes. This project will evaluate any differences between the two varieties in terms of adaptability and capacity to survive in roadside conditions. Due to prairie willows' natural adaptability and personal observations, it is hypothesized that prairie survival, plant dimensions, a subjective appeal rating for each plant, chlorophyll content, and the collection of representative stem from each plant to measure leaf dimensions and leaf area. Plant growth data would be collected once at the end of the first growing season (August 2026), twice in the second growing season (June and August 2027), and twice in the third growing season (June and August 2028). willow plants will thrive in the roadside environment- maintaining high survival rates and adequate growth and vigor. To formally assess prairie willow performance, data on site conditions and plant growth will be collected. Site data includes a soil pH, soil compaction, and light exposure (collected during planting). Plant survival and growth data include percent survival, plant dimensions, a subjective appeal rating for each plant, chlorophyll content, and the collection of representative stem from each plant to measure leaf dimensions and leaf area. Plant growth data would be collected once at the end of the first growing season (August 2026), twice in the second growing season (June and August 2027), and twice in the third growing season (June and August 2028).