Establishment of willows using the novel DeValix technique: ecological restoration mats designed for phytotechnologies

Abstract

Successful willow (Salix spp., hybrids and cultivars) establishment is a major determinant of their effectiveness when grown for phytotechnologies. Vertically-planted hardwood cuttings have been shown to produce adequate willow growth and survival, although site conditions at phytoremediation installations can make vertical planting methods unsuitable. The DeValix willow mat restoration technique was designed and tested as an alternative horizontal planting method that can be installed by hand in a variety of environmental applications. The DeValix technique was evaluated by testing five willow clones (“Millbrook”; “Sherburne”; “SX61”; “SX67”; “Tully Champion”) grown at two phytoremediation sites (Ontonagon, MI; Manitowoc, WI) for the 2019 growing season. Differences in survival and growth were tested among sites, genotypes, and their interactions. Stem height, diameter, and number of stems per mat were compared to identify clones with greater establishment success and higher phytoremediation potential. Results demonstrated significant effects of site (p < 0.0001) and clone (p < 0.0001) on shoot number. Additionally, the site × clone interaction significantly affected stem height (p = 0.0045) and diameter (p = 0.0166). Stem density ranged from 95,000 to 212,000 stems per hectare, indicating the DeValix technique is a viable establishment method for environmental applications, including phytoremediation and shoreline stabilization.

Novelty statement

This research analyzes the establishment success of the DeValix technique, a novel horizontal planting method for willow cultivars, and evaluates the DeValix technique as an alternative to other horizontal techniques and traditional vertical planting methods currently used in environmental applications. Results from this study add to the current knowledge of planting techniques and assesses the use of the DeValix technique for planting willow cultivars that are currently being tested in several phytotechnology systems.

Keywords:

• Biomass
• horizontal planting
• phytoremediation
• Salix
• Shoreline Stabilization
• Short Rotation Willow

Acknowledgments

The findings and conclusions in this publication are those of the authors and should not be construed to represent any official USDA or United States Government determination or policy. In addition, we are grateful to Ed Bauer, Faythe Erdmann, David Karlsson, Aleksander Peqini, and Molly Wagler for technical support in the field and greenhouse, as well as Dr. Mohamed Bayati and Mr. Ed Bauer for reviewing earlier versions of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was funded by the Great Lakes Restoration Initiative (GLRI; Template #738 Landfill Runoff Reduction). We are grateful to Karen Dorow, Dan Koski, and Kathleen McDaniel (City of Manitowoc, Wisconsin) and Dave Henderson (AECOM Technical Services, Inc.) for information about and access to the Manitowoc testing site, as well as Bob Pliska (Waste Management of Michigan, Inc.) for information about and access to Ontonagon.