Smithsonian Environmental Research Center

Ecologists Dennis Whigham, Donald Weller, and Thomas Jordan
have been working on new ways to rapidly assess ecosystem health on a grand scale.

Natural systems, like wetlands and forests, are much larger and much more complex than even the largest of man-made gardens. Evaluating the condition of such systems is an enormous task that involves assessing the density and diversity of organisms as well as the flow of water, nutrients, and animals through the system and between neighboring environments. This kind of evaluation has traditionally required large field studies in which researchers sample conditions at many locations within an ecosystem. Because of the amount of work involved, such assessments have traditionally been limited to small areas.

But SERC researchers Donald Weller, Dennis Whigham, and Thomas Jordan have taken a new approach that could change the way landscape ecologists do business. "One of our goals was to determine if available geographic data could be used to assess individual wetlands or the overall condition of wetlands in the watershed without having to do site-specific assessments based on field sampling," says Whigham.

By comparing field-based observations of wetlands with satellite data from satellite imagery and aerial photographs, the SERC researchers determined that certain features in the remote data corresponded to certain conditions observed in the field. That enabled them to create a statistical model through which they can now assess a large area using the remote data. Such rapid assessment over large areas was nearly impossible with traditional field-based studies.

As land managers and policy makers are continually asked to assess the health of the natural systems in their jurisdictions and to make decisions based on the health of those ecosystems, this kind of rapid assessment will become increasingly important.

"Rapid assessment methods for evaluating the functioning and biodiversity status of wetlands are mostly carried out at the scale of individual wetlands," said Whigham, "There is an increasing need for evaluating the condition of wetlands at the watershed scale." And that is exactly what this tool is designed to do.

The researchers do not expect their model to replace traditional field-based assessments, but their model extends the reach of ecologists by allowing them to study more space more quickly and effectively than ever before. "There is enough variability in the model that you wouldn't want to rely on the evaluation of one point to declare the condition of that specific spot," says Weller, "but if you evaluate many locations over a large area, the variability averages out and you get a very good understanding of the overall condition of a large area. And that's something that has eluded scientists limited by traditional field methods."

Results of their study and a description of the modeling tool were published in an article titled Assessing the ecological condition of wetlands at the catchment scale in a special issue of Landschap (Journal for landscape ecology and environmental sciences in The Netherlands).

Read an introduction and the abstract of this article here. For more information, visit the home pages of collaborating SERC researchers
Plant Ecology lab home page
Ecological Modeling Lab home page
Nutrient Lab home page

or contact
Dennis Whigham SERC plant ecologist and
WLO chair on landscape ecology at the Section of
Landscape Ecology, Department of Geobiology
Utrecht University.