The ability of a damaged ecosystem to repair itself, if left alone. For example, clear-cutting all trees in a well-defined watershed, then leaving them lie in place was the basis for a simple yet important experiment in the Hubbard Brook watershed of New Hampshire conducted by Dr. Gene Likens, while he was a faculty member at Dartmouth University. The downed trees and under story were sprayed with a mild herbicide for three years after the initial cutting to discourage the growth of seedlings, and then the entire system was left alone and carefully monitored. It is still being studied today as part of a long-term ecological study plan initiated by the National Science Foundation. It was demonstrated that the leaching of nutrients from unprotected soil was accelerated during the first three years, then returned to normal. During the first three years, pioneer species of plants grew out and provided shade for the shade tolerant tree species and held soil in place at the same time. These activities are referred to as ecosystem services. Eventually the trees overshadowed the shade intolerant pioneer species and they died out leaving only the trees. The aquatic conditions of the Hubbard Brook returned to normal after the third year. Resiliency was the term used to describe these events. It was postulated that resiliency of the Hubbard Brook watershed was due to a variety of factors, not the least of which was the fact that tree seeds were long lived in the soil and germinated after the clear-cutting. These studies give hope for other ecosystems damaged by the heavy hand of commercial logging and other forms of encroachment. The intimate connection between river and forest cannot be emphasized enough.