Kristina Blennow

To meet climate targets, expanding Populus spp. tree cultivation is proposed as a potential biomass feedstock, especially on agricultural land that does not come into conflict with food production. However, biomass potential assessments typically overlook landowners' perspectives, risking a gap between theoretical potentials and realisation. Here, we test empirical consequences of two hypotheses based on a survey targeting southern Swedish farmers: 1) Relying exclusively on agricultural land cover data to identify abandoned agricultural land leads to an overestimation of the total agricultural land that can be utilised for future biomass production from Populus spp. feedstocks. 2) The absence of data on farmers' intentions to cultivate fast-growing tree species on agricultural land leads to overestimation of the potential biomass supply from Populus spp. in biomass assessments. Findings suggest that less than 50 % of farmers with unsubsidised arable land, which is often assumed to be abandoned, would consider cultivating these tree species on this type of land (26 % [7–48]). Furthermore, only 11 % [6–17] would consider cultivating Populus spp. on agricultural land overall during 2021–2030, indicating a generally low level of interest among farmers. However, higher rates were observed in forested areas. The projected near-future cultivation potential of 2.0 kha [1.1–3.0] suggests an at least threefold overestimation in previous theoretical assessments. This study highlights a disparity between biophysical land data and producer perspectives, showing that neglecting farmers’ perspectives risks overestimating the biomass supply, potentially leading to misguided expectations and inefficient policies. Our findings support targeted policy recommendations.