Many changes in nature are slow and gradual, but sometimes extensive changes happen fast. Droughts, losses of production from rangelands, collapse of fisheries, toxic algae blooms, and outbreaks of disease or invasive species can occur rapidly, with significant impacts on living resources and large costs to society. Such big changes are difficult to forecast. Recent theoretical advances suggest that certain indicators can help foresee and manage big changes in resources before they occur. Like leading economic indicators, these leading ecological indicators can be observed before a big shift. So far these theories have not been tested in the field. This project will test potential indicators by experimentally inducing massive changes in the food chain of a lake, while monitoring the lake before, during and after the changes using modern sensor and signal processing technology. The research will evaluate the sensitivity of the indicators and whether they can be used to detect a large change in advance.
The project will assess leading indicators that could potentially be used to manage a wide range of living resources, while at the same time testing new theory about rapid extensive changes in nature. We will present a workshop and field trip on rapid environmental change for journalists at the Society of Environmental Journalists meeting in Madison in fall 2009. The project will train graduate and undergraduate students and contribute teaching materials for courses at the Institute of Ecosystem Studies, St. Norbert College, and University of Wisconsin-Madison.
While many ecological and environmental changes are moderate and gradual, some changes occur over relatively short periods of time and are dramatic. These unusually large changes, termed "regime shifts", may be irreversible or reversed only at great cost. Regime shifts have been identified as a frontier in ecosystem research because they can cause losses of key ecosystem services that can sometimes have severe consequences for human well being. Scientists are not yet able to predict when a regime shift is likely to occur in a given ecosystem. The ability to make such predictions could allow managers to intervene before the change occurred. Recent theory suggests that regime shifts are preceded by observable increases in variability of system components. We tested this theory with a whole lake experiment that altered food webs by adding a new top predator. We measured the variability of many components of the ecosystem (e.g. algal biomass) in both the manipulated lake and an adjacent non-manipulated reference lake. We used standard daily sampling methods and high-frequency (every 5 minutes) sensor methods. Modern signal processing approaches were used to detect change. We observed increases in the variability of several components of the ecosystem a year or more prior to the completion of the regime shift. These results supported the theory that there are statistically detectable indicators of ecological regime shifts. Our project is among the first large-scale field tests of theory and methods to anticipate regime shifts prior to their occurrence. Our results indicate that monitoring the statistical properties of indicators within an ecosystem may provide early warnings of regime shifts. These signals could allow ecosystem managers the opportunity to either prevent unwanted regime shifts or reduce the worst effects of regime shifts that cannot be prevented.
