Smithsonian researchers develop models to assess wetl...(ically important and wetland-rich waters...)

During the first year of the project, the researchers visited wetlands of both types, taking field measurements and observations according to the HGM protocol at more than 100 sites. They used the data to formulate models to rate the condition of the sites, which ranged from nearly undisturbed to highly degraded. The sites were chosen according to a statistical procedure developed by the Environmental Protection Agency to ensure that they were representative of the entire landscape.

For a subset of the sites, the researchers took a closer look at one important ecological function of wetlands: the cycling of nutrients, particularly nitrogen. Many watersheds are overloaded in nutrients due to runoff from agricultural fields and other sources. The result is diminished water quality. But soils in healthy wetlands contain bacteria that remove excess nitrogen by a process called denitrification and can restore water quality.

We found that you can predict denitrification potential from some fairly easy-to-measure properties of the soil, such as percent organic matter or pH, said Jordan, who led this portion of the study.

As a final step, the researchers took the results of the field assessments and compared them with digital maps and remotely sensed data, such as satellite land cover images.

The idea was to develop statistical models that would successfully predict what was observed in the field, said Weller, whose lab performed the analysis. Once youve developed the models, you then can assess additional wetlands without having to go out and sample them, he added. While the models cannot predict the precise conditions at a given site, they can provide enough information to identify potentially degraded areas and help guide management priorities in a watersh
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