nearby, relatively undisturbed settings, there is an increasing appreciation for the value of historical data from both documentary evidence and natural biotic and environmental archives (i.e., the proxy data described in Chapter 2) (e.g., Brenner et al., 1993; Brush, 1997). Indeed, for long-lived species such as trees, the long temporal framework provided by tree ring analysis is essential for understanding such important phenomena as fire frequency and migration rates (Swetnam et al., 1999). This historical approach to restoration has now matured to the point where techniques for reconstructing reference ecosystems and their historic range of variation are well established for a variety of terrestrial and coastal ecosystems (see Egan and Howell, 2001).

The application of historical ecology to issues of ecosystem restoration and management has enormous potential for both basic and applied research. In basic research, the integration and cross-calibration of observational, documentary, and proxy ecological data provides both a near-continuous and long-term ecological record as well as the opportunity to develop confidence limits for proxy indicators farther back in the geologic record. In applied research, the approaches of historical ecology demand close collaboration among biologists, geologists, and archaeologists engaged in ecosystem management and restoration—practical issues that are an increasingly important focus of the U.S. Geological Survey.