Physiognomy and Structure: This group includes spontaneously formed exotic tree-dominated stands, with irregular structure, or abandoned forest plantations, which may still show some evidence of row planting. Dominant trees may be hardwood or conifer.

Floristics: The tree layer is dominated (>80% cover) by exotic tree species. Understory shrub and herb species may be a mix of exotic species and native generalists. Dominant exotic tree species include Albizia julibrissin, Broussonetia papyrifera, Triadica sebifera (= Sapium sebiferum), and Maclura pomifera. Maclura pomifera is a native species in a narrow region of the eastern U.S., but is so widely planted outside of its range that it is effectively exotic. Minor native associates conifer Pinus taeda, and hardwoods Catalpa bignonioides, Catalpa speciosa, Liquidambar styraciflua, Liriodendron tulipifera, Maclura pomifera, and Quercus nigra.

Dynamics:  Exotic tree species may initiate establishment before natives or outcompete natives. Canopy cover may be as low as 10%, but eventually stands may have more-or-less continuous canopy, leading to a shift to a more shade-tolerant ground layer. The successional stages of this type have been described in many studies, particularly the early stages of tree invasion into old fields (e.g., Singleton et al. 2001). See also Wright and Fridley (2010) for the biogeographic variation among stands of this type. This type may also form in other ways. First, exotic forest plantation stands (tracked in 7. ~Agricultural & Developed Vegetation Cultural Class (CCL01)$$)) could become exotic ruderal stands if not intensively managed and the planted trees begin to die out. But because exotic planted trees only rarely regenerate on sites where they are planted, these stands more typically are invaded by native generalist trees and succeed to ~Eastern North American Native Ruderal Forest Group (G030)$$. Second, native forest stands that have not been plowed or planted may be stressed to the point where the characteristic native combination of species is altered (Curtis 1959). These stands are probably best tracked as altered variants of native types until the overstory itself is substantially altered to the point where exotics tree species are dominant.