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Data from: Suppression of the invasive shrub Rhamnus cathartica using foliar herbicide and herbaceous revegetation depends on canopy openness and the number and timing of interventions

Schuster, Michael12; Kaul, Andrew3

Published Jan 30, 2026 on Dryad. https://doi.org/10.5061/dryad.zkh1893qc

Data files

Jan 30, 2026 version files 1.32 MB

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Abstract

Many invasive shrubs re-establish quickly following initial management by resprouting vigorously from surviving stems and germinating from remaining seeds. Foliar herbicide is commonly used to treat resprouts but may not suppress re-invasion in the long-term since a single application is rarely comprehensive and many invaders recruit readily from seed. We tested whether follow-up foliar herbicide or herbaceous revegetation can suppress Rhamnus cathartica (common buckthorn) by creating 28 experimental blocks across seven sites in Minnesota, USA. We imposed a factorial combination of revegetation seeding (sown in spring 2017 or left to passive restoration) using a mix of 32 graminoid and forb species and foliar herbicide (fosamine ammonium) application timing (conventional timing – applied in fall 2017 and again in 2019 – or delayed timing – applied in 2019). We measured vegetation height, cover of functional groups, and buckthorn stem densities by size class in each of 2017, 2019, and 2021. Conventional timing of foliar herbicide initially reduced buckthorn density by 77 % and nearly extirpated buckthorn once completed, leaving only 0.6 % cover of buckthorn after two applications. Seeding increased the efficacy of herbicide such that seeded plots using conventional herbicide timing had the lowest cover of buckthorn and greatest amount of native vegetation. In delayed herbicide plots, seeding did not effectively reduce buckthorn cover or density. Abundance of herbaceous understory plants increased with canopy openness, especially with native seed addition. Using both repeated application of foliar herbicide and revegetation resulted in the lowest cover and density of buckthorn, therefore reducing needs for future interventions.