Potential Reinvasion of Lonicera maackii after Urban Riparian Forest Restoration

Abstract

The invasive shrub, Lonicera maackii, is known to change forest ecosystem communities and functions; however, few have studied the potential for this prolific invader to return after forest restoration. We studied the forest understory, canopy, seed bank, and incoming L. maackii seed rain in a riparian urban forest five to nine years after L. maackii removal and restoration efforts. We found the restored areas maintained a native canopy, but by nine years post-management efforts, L. maackii was becoming more important along multiple transects due to many small individual seedlings. The restored areas had greater herbaceous cover and species richness when compared to the control area (L. maackii-dominated). Lonicera maackii was not common in the seed bank during the study but was more prevalent in the seed rain of the restored forest with a tree canopy than in the restored open field without a tree canopy. While our results support the premise that removing L. maackii returns the community to a more native state, the study also shows that the native state would not last without additional minor intervention. Monitoring beyond ten years post-removal will be key to telling the whole reinvasion story, but management efforts every five to ten years could suffice to keep a restored forest dominated by native species.