Grantee Research Project Results
2003 Progress Report: An Experimental Study of Biological Invasions in Forests of the Eastern United States.
EPA Grant Number: R828900Title: An Experimental Study of Biological Invasions in Forests of the Eastern United States.
Investigators: Gurevitch, Jessica , Howe, Katherine , Hyatt, Laura , Lerdau, Manuel
Current Investigators: Gurevitch, Jessica , Lerdau, Manuel
Institution: The State University of New York at Stony Brook
EPA Project Officer: Packard, Benjamin H
Project Period: September 20, 2001 through February 19, 2004 (Extended to September 19, 2005)
Project Period Covered by this Report: September 20, 2002 through February 19, 2003
Project Amount: $451,553
RFA: Exploratory Research to Anticipate Future Environmental Issues (2000) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Water , Aquatic Ecosystems
Objective:
The invasion of native ecosystems by nonnative plants and animals is a major problem facing the United States in the 21st century, as well as being an enormous environmental problem globally. Invasive species can cause enormous detrimental effects to natural systems and have enormous economic costs. A major objective of this research project is to test specific hypotheses about what makes different natural communities more or less likely to become invaded by exotic species. We are conducting experiments in a range of protected forests in eastern Long Island, New York. These forests vary in species composition, soils, and the degree to which they are invaded by nonnative species. Although some forests are invaded heavily by alien plants, some hardwood forests and nearly al pitch-pine-dominated pine barrens appear to resist the establishment of nonnative species. We are carrying out experiments to test the effects of propagule (seed) availability, light, nitrogen, and calcium availability on factors hypothesized to limit forest invasibility. A second objective of this research is to examine ecosystem impacts of invasion by measuring the dynamics of litter decomposition (mass and nutrient loss) from leaves of native and invasive species. We predict that invasive species will have higher rates of mass and nutrient loss (i.e., faster decomposition) than natives and that these effects would be greater than site-specific effects. This is the first experimental study to test specific factors regulating the invasibility of forests and bring ecological community and ecosystem approaches together to better understand invasion in these ecological systems.
Progress Summary:
Responses to gaps were strongest for invasives in hardwood forest sites; responses of both invasives and natives to gaps in the pine barrens were smaller. Gaps consistently had far greater effects on plant performance than did nutrient manipulations. Invasive species did not grow faster than natives on average, but invasive plants had a greater positive response to gaps. Invasives allocated more biomass to shoots than did natives; natives shifted allocation in response to site differences and nitrogen addition, but invasives did not. Decomposition rates of both native and exotic taxa were accelerated in invaded hardwood forest communities compared to uninvaded hardwood forests, and all species decomposed more slowly in the pine barrens than in hardwood forest sites. Litter decomposition rates and nutrient release rates of exotic taxa were faster than those of closely related native taxa, despite similar macrodecomposer communities. Our results suggest that gaps created in the pine barrens are unlikely to facilitate invasions, but gaps in these hardwood forests likely are to increase invasion strongly. In addition, our litter decomposition experiments suggest that invasive plant taxa may have large effects on ecosystem processes that may facilitate further invasion.
This research has confirmed some of our hypotheses and offered some surprises that give numerous insights into the process of invasion of exotic species in forests. It has suggested fruitful avenues for future research that promises to extend our understanding of the interaction between invasive species and the ecological communities and ecosystems they invade.
Future Activities:
We are continuing our experiments on testing factors regulating forest invasibility in the eastern United States and investigating the impacts of differences in litter decomposition between native and invasive species and in invaded and uninvaded sites.
Journal Articles:
No journal articles submitted with this report: View all 35 publications for this projectSupplemental Keywords:
forest invasion, invasibility, exotic plants, decomposition, pine barrens, Long Island, northeastern US, experimental manipulation, field experiments, invasion ecology, water, land, soil, ecological effects, population, susceptibility, nitrogen oxides, ecosystem, terrestrial, habitat, public policy, conservation, biology, ecology, northeast, midatlantic, New York, NY, forestry,, RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Ecosystem/Assessment/Indicators, Ecosystem Protection, Forestry, Ecological Effects - Environmental Exposure & Risk, Monitoring/Modeling, Ecological Risk Assessment, Biology, Exp. Research/future, Futures, emerging environmental problems, extinction risk, ecological exposure, biodiversity, endangered species, forest, biopollution, runoff, shrubland, Eastern U.S., exploratory research, invasive species, forests, ecological dynamics, rainfallProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.