Soil seed banks predict future forest composition
Future forest composition can be predicted using soil seed banks. Years of deer overbrowsing in some eastern forests have resulted in understories lacking in species variety and incapable of regeneration. Seed bank studies often show a lack of correspondence between the existing vegetation and the seed bank; nonetheless, many late-successional species have been documented in more pristine forest seed banks. In West Virginia, Forest Service scientists and partners compared the soil seed banks of sites: (1) invaded by the exotic Ailanthus altissima; (2) dominated by the native Robinia pseudoacacia (black locust), an early successional site; (3) containing both Ailanthus and black locust, a mixed site; and (4) composed of a native trees in a mature forest. Soil samples were collected from under 10 trees at each site. The mixed Ailanthus and black locust sites had the most species-rich seed banks and the mature forest seed banks had the least. The Ailanthus-dominated sites had the highest exotic to native species ratio, and the black locust-dominated sites had the lowest. The mature forest seed banks contained about the same number of Ailanthus individuals as the Ailanthus-dominated sites. If ever harvested, these mature forests may follow a successional trajectory similar to that of the Ailanthus sites, and the Ailanthus sites are the least likely to recover after removal of existing invasive species.
Forest Service Partners