Shrub willow (Salix spp. and hybrids) is a biomass crop well adapted to the northeastern United States. We assessed the biomass productivity of six willow cultivars in a 14.5‐ha field in Pennsylvania through two rotation cycles of 3 yr each, comparing the realized and biophysical yield potential. We also evaluated the relationship of yield with plant density and the harvest efficiency. The realized yield of the best cultivars was about 8 Mg ha^–1 yr^–1, well below the calculated harvestable potential of 14 Mg ha^–1 yr^–1. Uniform stands of willow without planting gaps may maximize yield with 8 × 10³ plants ha^–1, but upright cultivars may benefit from higher densities. Harvest is relatively slow at 1 ha h^–1 or 20 Mg h^–1 in the longest rows with optimal ground conditions, which makes the harvest cost per hour high. Biotic stresses built up gradually during the 7 yr of the experiment affecting two cultivars severely. The cultivar S. miyabeana × S. viminalis ‘Preble’ was defoliated by a growing population of willow leaf beetle (Plagiodera versicolora), whereas the cultivar S. purpurea ‘Fish Creek’ was affected by two fungal diseases and suffered a major stand loss in the winter of 2019/2020. Both examples justify breeding for insects and diseases resistance. The moderate harvestable yield and high harvest cost imply that in the northeastern United States, the viability of willow for bioenergy with carbon capture and storage as a tool to reduce CO₂ emissions may depend on the provision and monetization of additional ecosystem services.

中文翻译：

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美国东北部柳树生物量生产的半商业案例研究

灌木柳（柳柳属和杂种）是一种非常适合美国东北部地区的生物量作物。我们通过两个分别为3年的轮作周期，评估了宾夕法尼亚州14.5公顷田地中六个柳树品种的生物量生产力，比较了已实现的和生物物理的产量潜力。我们还评估了产量与植物密度和收获效率之间的关系。最佳品种的已实现产量约为8 Mg ha ^–1  yr ^–1，远低于计算得出的14 Mg ha ^–1  yr ^–1的可收获潜力。没有种植间隙的均匀柳树架可以使8×10 ³公顷ha ^-1的植物最大化产量，但密度较高的直立品种可能会受益。在地面条件最佳的最长行中，收获相对较慢，为1 ha h ^–1或20 Mg h ^–1，这使得每小时的收获成本很高。在实验的7年中，生物胁迫逐渐建立，严重影响了两个品种。该品种Ş。宫be × S。viminalis'Preble '被越来越多的柳叶甲虫（Plagiodera versicolora）剥落，而S品种。purpurea'Fish Creek'受到两种真菌病的影响，在2019/2020年冬季遭受了严重的林分损失。这两个例子都证明了抗虫和抗病育种的合理性。适度的可收获产量和高收获成本意味着在美国东北部，柳树以碳捕集和封存作为减少CO ₂排放的工具的生物能源生存能力可能取决于其他生态系统服务的提供和货币化。