An Experimental Study of Biological Invasions in Forests of the Eastern United States.

EPA Grant Number: R828900
Title: An Experimental Study of Biological Invasions in Forests of the Eastern United States.
Investigators: Gurevitch, Jessica , Lerdau, Manuel
Institution: The State University of New York at Stony Brook
EPA Project Officer: Hiscock, Michael
Project Period: September 20, 2001 through February 19, 2004 (Extended to September 19, 2005)
Project Amount: $451,553
RFA: Exploratory Research to Anticipate Future Environmental Issues (2000) RFA Text |  Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Water , Ecosystems


One of the major environmental problems facing the United States in the 21st century is the invasion of native ecosystems by exotic species. These invasive species have the potential to reduce biodiversity, disrupt ecosystem function, and cause severe economic and social problems. Two challenges are paramount for ecologists regarding the issue of biological invasions; one is to try and understand why some communities and ecosystems are able to resist invasion while others are very susceptible so that strategies for preventing invasions can be developed. The second challenge is to understand the mechanistic bases for these often dramatic ecosystem effects so that efforts may be made to ameliorate them. This research addresses both of these challenges: exploring experimentally those aspects that are linked to resistance/susceptibility; and studying the mechanisms and dynamics by which invasions alter ecosystem processes.


We will test the hypothesis that three principal factors limit invasibility of forest ecosystems in the eastern United States. We propose that litter depth on the forest floor limits invasive species during the establishment phases and that nitrogen and calcium availability limit the growth of invasive species after they have established. We will experimentally test this hypothesis by examining the impacts of these factors and others (e.g., light and dispersal) in replicated plots across invaded and uninvaded ecosystems in New York State. In these plots we will manipulate light, calcium, and nitrogen availability singly and in combination. We will plant native and invasive species and measure their critical growth parameters. We will experimentally manipulate litter and study the establishment of both native and invasive species. We will also test the hypothesis that the myriad ecosystem impacts of invasions stem from initial differences in the dynamics of mass and nutrient loss between native and invasive species. We will measure these loss dynamics for each of the species under study and for the different ecosystem types, invaded and uninvaded, in which they are found. We propose that invasive species will have higher rates of mass and nutrient loss than natives, and that these differences will swamp site-specific effects.

Expected Results:

This study represents the first experimental study of factors regulating invasibility of forest ecosystems. In addition, this study is among the first to combine community and ecosystem approaches to invasion dynamics in forests of the eastern United States. The results from this research will enhance our understanding of the factors regulating susceptibility/resistance and increase our ability to protect forest ecosystems from invasions. Our exploration of mass and nutrient loss will improve our ability to measure rapidly the impacts of invasions, determine the potential threats posed by different invasive taxa, and derive strategies to mitigate these effects.

Publications and Presentations:

Publications have been submitted on this project: View all 35 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 2 journal articles for this project

Supplemental Keywords:

Forests; Eastern United States; Ecosystem Services; Invasion Prevention; Invasion Mitigation; Ecological Impacts; Nitrogen Deposition; Calcium Loss; Anthropogenic Changes; Global Change., RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Ecosystem/Assessment/Indicators, Ecosystem Protection, Forestry, Monitoring/Modeling, Ecological Effects - Environmental Exposure & Risk, 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, forests, invasive species, rainfall, ecological dynamics

Progress and Final Reports:

  • 2002 Progress Report
  • 2003 Progress Report
  • 2004 Progress Report
  • Final Report