Jen Sheldon is an ecologist who has spent a lot of time in Yellostone National Park. Her idea is to develop benchmark metrics for ecological systems using an intact ecological system like Yellostone as a benchmark that would allow us to measure the properties of any ecosystem and compare the observations to the standards and objectively assess the health of the ecosystem.
Animals are good proxies for the health of ecosystems. Animals concentrate information about an ecosystem because they are at the top of the food chain. In the example, Jen used antelope densities and modeled the ecosystem with a stack of layers. BY punching through at various locations she could create a table or spreadsheet of layer properties at that point. Compiling all these data points allows high and low points to be computed and correlated with observed animal densities. Essentially it makes it possible determine where it's good to be an antelope.
If you run a road through the ecosystem, you can now objectively quantify the impact. In other words you now have a quantifative impact model.
Yellowstone is the first benchmark ecosystem. Yellowstone is a good place to use to create these reference standards because it is an intact ecosytem that has been relatively untouched by human development..