The sustainability of purpose-grown biomass production on marginal lands in Canada is uncertain. In this study, an assessment of biomass yield and sustainability was performed for two poplar clones (Poplus deltoides × P. nigra, DN-34-PDN, and P. nigra × P. maximowiczii, NM-6-PNM) and two switchgrass cultivars (Panicum virgatum 'Cave-in-Rock'-SGC, and P. virgatum 'Nebraska'-SGN) on three marginal lands in Guelph (ON), Kemptville (ON), and Nappan (NS) in Canada. The differences in stem biomass across sites were not significant; however, differences in stem biomass among plants were statistically significant between poplar and switchgrass (p < 0.0001) and between poplar clones (p < 0.0001). The 2-yr stem biomass yield in PNM (15.27 ± 1.28 t ha −1 ) was significantly higher than those in PDN (7.02 ± 0.54 t ha −1 ), SGC (2.57 ± 0.28 t ha −1 ), and SGN (1.45 ± 0.22 t ha −1 ). Two sustainability indices based on macronutrients (MBSI) and nitrogen (NBSI), were developed to assess sustainability. Both indices show that the biomass production system of high-yielding poplar clone PNM depicts nutrient loss and may require external nutrient inputs via fertilization during the establishment phase. Higher index values for switchgrass SGC (1.47 ± 0.22, 1.11 ± 0.15) and SGN (1.37 ± 0.16, 1.17 ± 0.12) for MBSI and NBSI, respectively, indicate that despite low stem biomass yields, switchgrass biomass production is sustainable. These findings suggest that, from a nutrient perspective, sustainable biomass production systems can be established on marginal lands in Canada; however, there is a trade-off between high yield and long-term sustainability in purpose-grown biomass production systems.Key words: marginal lands, nutrient, poplar, sustainability, switchgrass.Résumé : On ignore dans quelle mesure la production de biomasse sur les terres marginales du Canada serait une activité durable. La présente étude évalue le rendement de la biomasse et la pérennité de deux clones de peuplier (Poplus deltoides × P. nigra, DN-34 -PDN, et P. nigra × P. maximowiczii, NM-6 -PNM) ainsi que de deux cultivars de panic raide (Panicum virgatum cv. Cave-in-Rock -SGC et Panicum virgatum cv. Nebraska -SGN) sur trois terres peu productives situées à Guelph (ON), à Kemptville (ON) et à Nappan (NS), au Canada. La biomasse des tiges n'a pas varié de façon significative aux trois endroits, cependant, l'écart entre la biomasse des peupliers et celle du panic raide est statistiquement significatif (p < 0,0001), de même que l'écart entre la biomasse des deux clones de peuplier (p < 0,0001). Le rendement en biomasse de PNM au cours des deux années de l'étude (15,27 ± 1,28 t par hectare) était sensiblement plus important que celui de PDN (7,02 ± 0,54 t par hectare), de SGC (2,57 ± 0,28 t par hectare) et de SGN (1,45 ± 0,22 t par hectare). Les auteurs ont élaboré deux indices pour évaluer la pérennité d'après la concentration de macronutriments (MBSI) et celle d'azote (NBSI). Les deux indices révèlent que la production de For personal use only.biomasse ...