Non-native species in new habitats may out-compete native species, decreasing the diversity and ecosystem function of the plant community. Hypericum perforatum (St. Johnswort) is a weedy perennial native to Europe that has become particularly problematic in pastures and waste places in the central and western United States and Australia. H. perforatum can spread aggressively by vegetative reproduction of its extensive root system and also produces a large seed bank that can remain in the soil for up to 30 years. An understanding of the soil seed bank may lead to a better understanding of the spread and establishment of invasive plant. The seed bank provides some insight into what species may have existed in the community in the past, what species may exist in the future, and what species may exist in nearby communities. Because the seeds of invasive species must arrive in the soil before they are able to establish in the plant community, the seed bank can show potential invaders before they are present in aboveground vegetation. The seed bank also offers a reserve for new recruitment in the vegetation after a disturbance and can play a major role in community restoration.
Results/Conclusions
We examined the relationship between the soil seed bank and the aboveground vegetation in managed meadows on the Prescott Peninsula in the Quabbin Reservoir watershed near Shutesbury, Massachusetts during the summer of 2007. The native species Hypericum punctatum has similar habitat requirements as H. perforatum, yet it was missing from the vegetation where H. perforatum was present. We also collected soil samples from our vegetation plots and used a method of greenhouse germination to examine the soil seed bank. Preliminary germination results have indicated H. perforatum seeds in plots where the species was not present in aboveground vegetation. Although no H. punctatum has appeared in the germination tests, other native species are present in the seed bank. Using herbarium data we have mapped the distribution of H. perforatum, H. punctatum, H. ellipticum, H. virginicum, H. mutilum, H. canadense, and H. majus in Massachusetts since the 1800s.