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Ecology and Management of Invasive Species and Forest Ecosystems

Tools for Understanding Biological Invasions

Biological invasions can be broken down into four distinct population processes: arrival, establishment, spread, and impactArrival is the process by which individuals are transported to new areas outside of their native range.  Rising levels of world trade and travel have resulted in an ever-increasing arrival of alien species; however, most of them have failed to establish. Establishment occurs when populations grow to sufficient levels that extinction is highly unlikely.  The establishment phase thus represents a critical period. Founder populations typically are small and consequently are at great risk of extinction. Generally, the smaller the founder population, the less likely is establishment.  Spread of a nonindigenous organism is a process by which the species expands its range from a habitat it currently occupies to new habitats or areas. It can be described in several ways, but most often we estimate spread as an increase in range radius over time, and there can be considerable variability in the spread rates for various species of invading insects.  Only after the non-native species is widespread and abundant does it cause some sort of ecological or economic harm and become “invasive.”  This fourth stage is labeled the impact stage.


Within the northeastern and midwestern U.S., non-native species occur in all stages.  Understanding the biology, ecology, and impacts of invasive species is necessary to develop appropriate management strategies.  Different management approaches and tactics are used at different phases of invasion and under different situations.  We conduct research to improve our understanding of the biology and ecology of invasive species and of the ecology and dynamics of the invasion process.  Our research covers all four phases of the invasion process, including analysis of pathways and risk of arrival; factors that influence establishment; modeling spread of invasive species; and development of management tools to mitigate impacts after establishment.

Our Research