Exotic Plant Inventory, Landscape Survey, and Invasiveness Assessment: Roosevelt-Vanderbilt National Historic Sites, Hyde Park, NY

An exotic plant cultural landscape inventory, area wide survey, and natural resource area invasiveness assessment was conducted in 2002 at the Roosevelt-Vanderbilt (ROVA) National Historic Sites (NHS) in Hyde Park, NY. At the species level, 40% of 90 assessed landscape species had not escaped cultivation, 44% had escaped and invaded natural resource areas, and 16% were categorized as migratory invaders. The most prolific introduced woody trees and vines at ROVA are members of the trumpetvine, bittersweet, pea, buckthorn, quassia, and grape families (Bignoniaceae, Celastraceae, Fabaceae, Rhamnaceae, Simaroubaceae, and Vitaceae, respectively). Shrub species occurring with more frequency in the natural areas than other escapes are the introduced native atlantic nine bark (Physocarpus opulifolius), burning bush (Euonymus alatus), forsythia (Forsythia sp.), japanese barberry (Berberis thunbergii), morrow’s honeysuckle (Lonicera morrowii), tatarian honeysuckle (Lonicera tatarica), and mock orange (Philadelphus sp.). For the subset of assessed woody vines, shrubs, and tree species found in cultivation for at least 50 to 67 years (the ‘‘50 plus club species’’), slightly more had escaped from cultivation for the Vanderbilt Mansion (VAMA) and Eleanor Roosevelt (ELRO) estates but for the Franklin Delano Roosevelt (FDR) collection the numbers were equivalent. The approach used in this study illustrates with data the ‘‘movement’’ of exotics over a significant period of time and underscores the importance of site-specific and species-specific assessments. This assessment also emphasizes the value of understanding the history (e.g., cultivated, cultivated escaped, or migratory invaders), purpose (e.g., aquatic, crop garden forb, groundcover, ornamental, or weed), and management over time (e.g., long since abandoned, recently abandoned, or still maintained, etc.) of the geographic area under consideration and the use of available exotic invasive plant lists to conduct such assessments.