Skip to main content
ARS Home » Northeast Area » Washington, D.C. » National Arboretum » Floral and Nursery Plants Research » Research » Publications at this Location » Publication #378031

Research Project: Evaluation and Genetic Improvement of Woody Ornamental Landscape Plants

Location: Floral and Nursery Plants Research

Title: Yield and biomass quality of shrub willow hybrids in differing rotation lengths and spacing designs

item Gouker, Fred
item FABIO, ERIC - Cornell University
item SERAPIGLIA, MICHELLE - Cornell University
item SMART, LAWRENCE - Cornell University

Submitted to: Biomass and Bioenergy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/17/2021
Publication Date: 2/2/2021
Publication URL:
Citation: Gouker, F.E., Fabio, E., Serapiglia, M., Smart, L. 2021. Yield and biomass quality of shrub willow hybrids in differing rotation lengths and spacing designs. Biomass and Bioenergy. 146:105977.

Interpretive Summary: Willow biomass produced in short rotation coppice systems can be used as biomass feedstock in the United States, Europe and Canada. However, most researchers focus on data from the first harvest rotation only, whereas multiple rotations have been rarely investigated. The aim of this study was to evaluate the effect of 10 pre-commercial cultivars, planting design (single-row vs double row), and harvest cycle (two-year vs four-year) on biomass yields during 10 consecutive years. Quantifying these changes is important when modeling production and cash flow of these perennial systems. During the 10-year period, yields were higher after the first harvest in the two-year rotation. This implies that high biomass yields can be obtained after the first harvest rotation if willows are cultivated with the two-year, single-row spacing and rotation design producing greater yields overall. Additionally, a newly bred triploid hybrid, produced the greatest yield regardless of planting design or harvest cycle. Results from this study suggest a shorter cutting cycle may increase annual productivity. Cultivar performance from this study also adds to the growing evidence that interspecific triploid hybrid cultivars tend to outperform diploids.

Technical Abstract: To study the effects of planting design and harvest cycle on shrub willow bioenergy crops, 10 hybrid shrub willow cultivars were established in a split-plot trial, with half the plots in a double-row design and the other half in a single-row design. Both double-row and single-row designs were established with the same stand density, ~14,000 plants ha-1. The single-row design was harvested four times on a two-year cycle from 2009-2018. The double-row plots were harvested twice on a four-year cycle. Biomass yield, growth parameters, wood composition, specific gravity, and calorific values were evaluated. Mean annualized yield over eight years from the single-row design was 9.98 Mg ha-1 yr-1 whereas mean annualized yield for the double-row spacing design was 9.32 dry Mg ha-1 yr-1. Cumulative biomass production averaged across all genotypes from four biennial, single-row harvests resulted in 79.9 Mg ha-1 compared with two quadrennial double-row harvests of 74.5 Mg ha-1. A triploid hybrid, LA970253, produced the greatest yield in both designs. In both planting designs, hemicellulose and cellulose content increased over time, while lignin and ash content decreased. Calorific values ranged from 17.62 to 19.02 MJ kg-1 with no significant differences between designs or genotypes. The results from this study suggest a shorter cutting cycle may increase annual productivity but may be dependent on cultivar.