Established Short‐Rotation Willow ( Salix spp.) as an Effective Facilitator of Native Hardwood Tree Regeneration in New York State, USA

Abstract

Abstract

ABSTRACT Afforestation of former agricultural land is increasingly prioritized as a natural climate solution, yet tree establishment is inhibited by herbaceous competition, browsing pressure, limited seed dispersal, and planting costs. Short‐rotation willow ( Salix spp.) crops could provide renewable biomass for multiple rotations and subsequently transition to forest by facilitating hardwood establishment through rapid canopy closure, suppression of competing vegetation, and improvement of site conditions. This potential, hardwood regeneration within nine willow fields in New York State was assessed using two sequential studies. In study 1, a rapid point‐quarter survey quantified seedling density, height, and spatial gradients relative to seed sources. In a follow‐up study, fixed‐area plots were established across these gradients to quantify seedling densities and evaluate stand, soil, and seed‐source proximity attributes. Hardwood regeneration was dominated by wind‐disseminated species, primarily Fraxinus and Acer spp., with mean densities reaching 30,000 seedlings ha −1 in some locations. Regeneration was spatially structured, declining with increasing distance from seed sources; densities typically fell below 2500 seedlings ha −1 beyond 40–75 m from forest edges. The point‐quarter method underestimated fixed‐plot densities but reliably distinguished areas of high and low regeneration. Logistic regression indicated that regeneration exceeding thresholds associated with successful forest establishment (1500 and 2500 seedlings ha −1 ) was positively related to proximity to seed sources and higher willow survival, whereas other soil and stand properties were not associated with seedling density. These findings suggest that short‐rotation willow systems could function as a hardwood nurse crop and integrate biomass production with afforestation.