Control of Invasive Japanese Climbing Fern (Lygodium japonicum) and Response of Native Ground Cover During Restoration of a Disturbed Longleaf Pine Ecosystem

Japanese climbing fern (Lygodium japonicum) is an invasive species prevalent through the southeastern United States that grows on, around, and intermingles with native groundcover in a variety of forest ecosystems. Management of this species can be problematic because herbicide control must also ensure minimal impact to native plants, particularly in ecosystems undergoing restoration and recovery from disturbance. We tested 3 herbicides (glyphosate, imazapyr, and metsulfuron methyl) at various rates, alone and in combination, to evaluate their efficacy for fern control and impacts to non-target, native groundcover in a longleaf pine (Pinus palustris) ecosystem subject to dormant season burns and hurricane and salvage logging disturbances. All herbicide treatments reduced Japanese climbing fern cover by 77-98% at 1 yr following treatment, but at 2 yr there was considerable re-growth on imazapyr and metsulfuron-methyl treated plots. Glyphosate applied alone as a 2 or 4% solution provided 91-98% fern control after 2 yr, and there was no significant improvement using combinations of glyphosate with other herbicides. Climbing fern cover increased by 70% in the untreated control. We found a significant correlation between reduction in fern cover and increase in other vegetation, though species composition changed minimally. Species richness at 2 yr after treatment increased by 2-3 species following application of glyphosate alone or in combination, and decreased on the untreated control. We recommend directed spray applications using 2% glyphosate solutions for efficient control. Using this approach on matted fern should result in little detriment to native groundcover, even with this broad-spectrum herbicide.