The authors compare past distribution data from historical records, and current data from Brooklyn Botanic Garden’s New York Metropolitan Flora Project to determine changes in distribution over the past century. They further compare these changes between native and introduced species within the same genus, such as Celastrus scandens, American bittersweet (native) and Celastrus orbiculata (or C. orbiculata), Oriental bittersweet (introduced, and invasive), or Lonicera sempervirens, Trumpet honeysuckle (native) and Lonicera japonica, Japanese honeysuckle (introduced, and invasive).

We statistically analyzed 100 years of herbarium specimen data for woody plants in the New York metropolitan region in order to measure the floristic changes of this area. Change Index values were computed for 224 of the region’s 556 woody species to provide a specific measure of whether these species are expanding, contracting, or stable. The results show that, in general, nonnative invasive species are spreading rapidly in the region, while native species are in slight decline.
– The Changing Flora of the New York Metropolitan Region

Links

The Changing Flora of the New York Metropolitan Region, Urban Habitats, Volume 3, Number 1, Fall 2005, Brooklyn Botanic Garden, 1000 Washington Avenue, Brooklyn, NY 11225