Ecologist Steven Carpenter to speak at St. Olaf

Lecture by world-renowned limnologist and ecologist Steve Carpenter: "Early Warnings of Big Changes in Ecosystems"

Many important changes in ecosystems involve regime shifts in which an ecosystem crosses a critical threshold. Examples are collapse of exploited populations of fish or wildlife, eutrophication, epidemics, colonization by invasive species, desertification, conversion of rangeland to shrubland and many others. Ecological thresholds are sometimes difficult to measure, and consequently the precise location of ecological thresholds is highly uncertain. In management, crossings of ecological thresholds often come as surprises. If a critical threshold is approached gradually, however, there are early warnings of the impending regime shift. The status of research on early warning indicators, and their strengths and weaknesses, will be discussed.