Rachel Johnson
Invasion by non-native plants into early successional areas, especially human-disturbed sites, is well-documented. Less well studied, however, is the invasion by exotic plants into established forests. At least 24 woody species have invaded forest sites in the eastern United States, and experimental studies suggest that these invaders may have negative effects on the forest ecosystem. One woody forest invader that has not been well studied is Euonymus alatus (winged euonymus, burning bush), which can grow in a variety of soil and light conditions, including full shade. E. alatus usually occurs in separated, patchy populations. Five populations of E. alatus were characterized by density, age structure, and size structure. Physical and biological site variables, including light, soil features, topography, browse, and associated vegetation were described. This research tests the relative roles of seed dispersal versus physical and biotic factors in controlling population structure. Dispersal may limit the spread of Euonymus alatus in the study area if presence and size distribution show no relationship to light levels, edaphic characteristics, topography or vegetation. In contrast, a strong positive correlation between any of the measured physical or biological variables and the observed distribution and abundance of Euonymus alatus in the study areas will indicate that these populations are possibly constrained by physical or biological site-related factors. The presence of all-aged populations with high juvenile abundance suggests that populations will persist on site; if populations are single aged and dominated by older plants, then persistence is unlikely or dependent on disturbances that allow establishment.
Keywords: BURNING BUSH, EUONYMUS ALATUS, INVASIVE SPECIES, NEW ENGLAND FORESTS
