Thinking Locally for Urban Forest Restoration: A Simple Method Links Exotic Species Invasion to Local Landscape Structure

Abstract

Restoring urban forests often involves eradicating exotic species and diligently guarding against future invasions. Understanding how landscape structure contributes to the distribution of exotic species may inform these management efforts. To date, the distribution of exotic species in forested patches has been correlated with the type of development surrounding the patch, with those surrounded by agricultural or urban development often more highly invaded. Yet, previous studies have categorized land use types and have not examined more local-scale changes in land use. These local changes may be particularly important in urban areas where forested patches are immediately surrounded by diverse land use types. Our study examined how two key aspects of landscape structure, patch size and adjacent land use, may influence patterns of exotic species invasion of riparian buffers within Raleigh and Cary, North Carolina, United States. We found that large patch size alone, in our case, wide riparian buffers, does not protect against exotic species invasion. Patches surrounded by higher canopy-cover landscapes (e.g., forests and older residential developments with mature canopy) were more likely to be invaded than those surrounded by less canopy cover (e.g., shopping malls and other commercial development). We attribute these results, in part, to increased pressure from exotic propagules from adjacent forests. When restoring urban forests, attention should be paid to local land use to better plan for successful, long-term eradication of exotic species.

Provincial and cosmopolitan: floristic composition of a dryland urban river

“…Many of these cultivars have been repeatedly introduced in cities or villages throughout the world, facilitating a Bspillover effect^and spread beyond their planting zones (Reichard and White 2001). As is often the case where managed and natural landscapes abut, several of the landscape plants have become naturalized within the urban riparian forest (Richardson et al 2000;Vidra and Shear 2008;Blitzer et al 2012;Litteral and Wu 2012). Genetic studies would be useful to confirm that the Phoenix urban plantings were indeed the source of the naturalized riparian populations along the Salt River (Vardien et al 2013).…”

Growth evaluation of native tree species planted on post coal mining reclamation site in East Kalimantan, Indonesia

“…Assisted reclamation of ex-mining areas recover faster than nonassisted ones, both in the rate of topsoil accumulation and biomass increase of plants (Pietrzykowski 2008). In the beginning of revegetation, plant's growth must be assisted from cosmopolitan alien species that are able to survive in unfavorable environmental conditions, in order to create a favorable ecosystem (Herrick et al 2006;Vidra and Shear 2008). The presence of recolonizing species which are more adaptive and mostly invasive might disrupt the growth of local plant species in the reclamation area.…”

The influence of urban land use on seed dispersal and wetland invasibility

“…However, while many studies of sites along urban-to-rural gradients have documented higher amounts of invasion in the urban than in the rural sites in both existing vegetation (Moffatt et al 2004;Borgmann and Rodewald 2005;Loewenstein and Loewenstein 2005) and in seed rain and seed banks (Kostel-Hughes and Young 1998;Honu and Gibson 2008;Lin and Cao 2009), comparisons of sites within developed regions have demonstrated that there is great variability in the degree of invasion among such sites, often correlated with differences in the surrounding types of urban land use (Ehrenfeld 2008;Oneal and Rotenberry 2008;Vidra and Shear 2008). Although these studies document the range of invasion found in urban regions, the mechanisms generating differences in invasion among urban land uses remain unknown.…”