Impacts of removing Chinese privet from riparian forests on plant communities and tree growth five years later

An invasive shrub, Chinese privet (Ligustrum sinense Lour.), was removed from heavily infested riparian forests in the Georgia Piedmont in 2005 by mulching machine or chainsaw felling. Subsequent herbicide treatment eliminated almost all privet by 2007. Recovery of plant communities, return of Chinese privet, and canopy tree growth were measured on removal plots and heavily invaded control plots in 2012 approximately five years after complete removal of privet. Plant communities were also measured on three 'desired future condition' plots which were never heavily infested with privet. These areas provided a goal condition for plant communities on removal plots. Approximately 7% of mulched plots and 3% of felling plots were re-infested by Chinese privet. In contrast, non-privet herbaceous plants covered 70% of mulched plots and 60% of felling plots compared to only 20% of untreated control plots and 70% in desired plots. Both mulched and felled plots had more plant species than the control plots, and mulched plots had more species than felled plots. Analysis of similarity (ANOSIM) and non-metric multidimensional scaling (NMS) ordination indicated that control, removal, and desired future condition plots had three distinct plant communities but the methods used to remove privet did not result in different communities. There was no difference in growth of canopy trees in removal and control plots five years after removal. Removing Chinese privet from riparian areas is beneficial to plant communities, promoting biodiversity and secondary succession while progressing toward a desired condition regardless of the method used to remove it. Chinese privet, Ligustrum sinense Lour. (Oleaceae), was first introduced as an ornamental plant in 1852 (Dirr, 1983). By the 1930s, it had escaped cultivation and was widely established in floodplains across the Southeastern U.S. (Small, 1933). It is now estimated to inhabit 1 million ha in the southeast (Miller et al., 2008). These estimates are misleading however, due to the underestimated area that privet inhabits in cities, towns, and along roadsides. Privet is common in riparian areas, possibly because they are similar to its native habitat in China (Langeland and Burkes, 1998). These areas also appear to be susceptible to invasion (Stroh and Struckhoff, 2009), probably due to the same factors that contribute to the overall increased biodiversity that occurs in them (Planty-Tabacchi et al., 1996; Hood and Naiman, 2000). Favorable habitat combined with less herbivory on privet and greater fruit production, when compared to native shrubs of the same family (Morris …