Processes regulating the invasion of European buckthorn (Rhamnus cathartica) in three habitats of the northeastern United States

Abstract

Invasion by exotic plants often is restricted by processes, such as seed predation, acting on early life-history stages; however, the relative importance of these processes might vary among habitats. Modern human land use has created a mosaic of habitats in many landscapes, including the landscape of the northeastern United States. European buckthorn (Rhamnus cathartica) is an exotic plant that has achieved varying success in North American habitats. We studied dispersal, seed survival, germination, and seedling survival of buckthorn populations at four plots in each of sugar maple (Acer saccharum) forests, old fields, and abandoned conifer plantations in central New York State. Dispersal was low in maple forests, as evidenced by low collection rates of R. cathartica seeds in seed traps. Rates of post-dispersal seed predation were highest in maple forests and lowest in old fields, suggesting greater use of maple forests by granivorous rodents. Germination rates did not vary among seeds planted in soils of these habitats when studied in the laboratory despite differences in soil pH. Survival of transplanted seedlings was low in maple forests relative to old fields and plantations. Buckthorn invasion of old fields and abandoned plantations was not strongly constrained by factors we considered, and the buckthorn populations in these habitats were large. A combination of low dispersal by frugivores, low seed survival due to predation, and low seedling survival due to dim light conditions apparently prevents R. cathartica from invasion of intact maple forests of our area. Native fauna and canopy closure may act synergistically to reduce success of invasive plants in natural habitats.

From pest data to abundance‐based risk maps combining eco‐physiological knowledge, weather, and habitat variability

“…Spatially explicit maps or exhaustive data of buckthorn distributions do not exist for Wisconsin, but information about some habitat preferences of R. cathartica (common buckthorn) are known (Knight et al. , McCay and McCay ). The common buckthorn colonizes mainly deciduous forest edges, wetlands, and shrublands, and is rare or absent in coniferous forests and on acidic soils (Gassmann , Kurylo et al.…”

Using revegetation to suppress invasive plants in grasslands and forests

“…Consequently, the assemblages of native species that best suppress reinvasion by IPS may often be distinct from the perceived historic, un‐invaded state. For example, stands of the tree Acer saccharum (Sugar maple) can create exceptionally heavy shade and be resistant to invasion of R. cathartica in northeastern North American (McCay & McCay, ). In the same region, stands of oak trees ( Quercus spp.)…”

Forest dynamics at Minnesota's prairie-forest border driven by invasive buckthorn (Rhamnus cathartica) and native bur oak (Quercus macrocarpa)1

“…Heimpel et al (2010) describe R. cathartica as a foundational species in an ''invasional meltdown'' involving 11 linked Eurasian species. Published studies of resource requirements and microsite utilization by R. cathartica, however, remain sparse Graves 2006, Knight et al 2007) though see Grubb et al (1996), Harrington et al (1989) and McCay et al (2009). We know of no research on the performance of R. cathartica at the western (dry) end of its range.…”