Speaker: Dr. Jessica Gurevitch
Affiliation: Stony Brook University
Seminar Title: Landscape demography and a different perspective on biological invasions
Abstract: This talk will consist of three parts. I will introduce the concept of landscape demography, illustrate its application in a study of the invasion of Centaurea stoebe, spotted knapweed, in New York State and briefly discuss the results of a systematic review and field synopsis of the literature seeking to explain the success of biological invasions.
Demography, the study of the dynamics of populations and the underlying factors determining those dynamics, is central to understanding many ecological phenomena and to answering both fundamental and applied questions about organisms in nature. Most studies of plant and animal demography have been carried out a local level on one or a few populations, although some of the most critical ecological processes occur at intermediate spatial scales, across landscapes and regions. Landscape demography (LD) focuses on patterns in the dynamics of multiple populations of a species at landscape scales. This approach is relevant to a range of important phenomena, including biological invasions, declines in threatened or endangered species, range shifts of native or invasive species in response to climate change, and natural fluctuations in numbers and distributions of populations of native species over time. Landscape demography differs from meta-population ecology in important ways, in that LD focuses on patterns of variation in demographic parameters (e.g. fecundity and survival), drivers of correlations in those parameters across scattered populations at landscape scales, and on the consequences of this variation for heterogeneity in the growth rate of populations across larger spatial scales. I illustrate this approach with an ongoing study of the landscape demography of Centaurea stoebe on Long Island and in the Adirondack Mountains. C. stoebe is a major noxious invader in grassland systems in the western U.S., and is becoming highly invasive in the northern Great Lakes. It has been widely naturalized in the eastern and Midwestern U.S. and is showing signs of being on the cusp of rapid population increase in New York State. Our goal is to develop a picture of the early stages of invasive population increase of C. stoebe at a landscape scale. Finally, I present the results of a broad systematic review of >2000 studies seeking to explain the success of biological invasions across a wide range of organisms, systems and geographic regions.