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The utility of seed addition to promote tree regeneration can be greatly limited by animals that consume seeds. Moreover, given that restoration often occurs in forests where invasive shrubs are abundant, and evidence that invasive shrubs can increase granivory, it is important to explore whether methods for reducing granivory work equally well in invaded and uninvaded habitats. We used a multi-site field experiment spanning 160 days to explore whether coating seeds of Prunus serotina with capsaicin extract leads to reduced granivory in habitats with or without invasive shrubs ( Rhamnus cathartica). Capsaicin-coated seeds were removed at a similar rate to uncoated seeds, but seeds in invaded plots had a 78.8% higher rate of removal compared to plots without invasive shrubs. Our findings suggest that managers seeking to encourage regeneration of native trees using direct seeding should consider invasive shrub removal as a top priority to limit the loss of seeds once sown.
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This content will become publicly available on March 21, 2026
Promoting acorn survival using capsaicin seed coatings is strengthened by the removal of invasive shrubs
Promoting regeneration of native trees, likeQuercusspp., is a priority for land managers given the ecological and economic importance of oak woodlands. Although direct seeding may promote recruitment ofQuercusspp., the effectiveness of direct seeding may be greatly reduced in environments where the activity of granivorous rodents is high. Importantly, the activity of granivorous rodents may be highest in environments where oak restoration is most desired, such as habitats invaded by non‐native woody shrubs. Implementing chemical deterrents to granivory should promote direct seeding success; yet it is essential to understand if those deterrents are effective in challenging restoration situations (e.g. areas with dense invasive shrub cover). Moreover, it is important to determine whether chemicals that deter granivory have undesired effects on beneficial ecological interactions, such as animal‐mediated seed dispersal. We used multi‐field site experiments in shrub‐invaded and shrub‐cleared forest plots to compare the removal and dispersal ofQuercus rubraacorns with seed coats treated with a pepper‐based capsaicin extract versus acorns treated with control solutions (i.e. water and ethanol). Seed removal was quantified for 37 days, and seed survival and dispersal were quantified by relocating nail‐tagged acorns after 8 weeks. We found that capsaicin‐treated seeds had a significantly higher probability of survival compared to seeds treated with control solutions; the presence of the invasive shrubRhamnus catharticaincreased post‐dispersal seed consumption regardless of seed‐coat treatment; capsaicin did not affect acorn dispersal distance; and the concentration of capsaicin coatings on acorns declined over time in the field.
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- Award ID(s):
- 2110031
- PAR ID:
- 10588984
- Publisher / Repository:
- Society for Ecological Restoration
- Date Published:
- Journal Name:
- Restoration Ecology
- ISSN:
- 1061-2971
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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