Rutgers University Newark, New Jersey, United States
Background/Question/Methods
Species from distant regions are being transported through the agency of humans and are increasingly entering native biotic communities as non-native species. One of the consequences of the arrival and establishment of non-native species is a mixing of earth’s biota to the extent that today composition, structure, and function of biotic communities are altered almost everywhere, and novel communities are formed. In North America, biological invasion has a long history beginning with the ‘biotic Columbian exchange’ more than 500 years ago and since then many plant species has been added to the local flora. Here we explore the possibility and extend extent of re-assembly of plant communities that are dominated by species that share a common geographic origin. They re-assemble into foreign communities that potentially resemble and function similar as in communities in their original range. Concentrating initially on spontaneous vegetation on disturbed sites and extending it to less human-influenced areas, we investigate the degree of “foreignness” of such plant communities and analyze the contribution of non-native species to the resulting novel communities. To better understand such communities, we studied the interaction of species from similar origin and species that differed in their origin.
Results/Conclusions
We were able to identify communities dominated by plant species with a common origin, which therefore re-assembled into which what could be called “expatriate plant communities. A survey of spontaneous plant communities on disturbed sites in New Jersey demonstrates that it is possible to discern patches with such expatriate plant communities. Asian communities were predominately mostly found in disturbed forests and forested wetlands, European communities in post-industrial sites, while native communities were mostly found in post-agricultural sites. Less disturbed sites in arid and semi-arid regions of the American SW are today dominated by Old World annual grasses and forbs and form communities that resemble the ones typical to arid regions in the Old World. In urban and sub-urban northern New Jersey, we tested and confirmed that such assemblies were not merely the result of random combinations from a regional species pool that consist of native and non-native species. In some cases, these re-assembled expatriate plant communities appear to attract non-native herbivores (such as Spotted Lanternflies) that resemble in function the ones found in the region of origin of the new invaders. It remains to be investigated whether such multi-trophic, re-assembled communities resemble and function similar to original communities.
