Observing Physical and Biological Change Through Historical Photographs
BLM has published several technical references to aid its field personnel in managing the 269 million acres of public lands and resources for which it is responsible. Many of these technical references emphasize the need to collect and analyze historic information in order to better assess the potential of ecological sites. The purpose of this technical reference is to provide resource specialists with the basic information, concepts, and procedures associated with using historical photographs to analyze changes that have occurred on specific ecological sites in relationship to possible change agents.
This document supplements technical references 1737-7, Procedures for Ecological Site Inventory-with Special Reference to Riparian-Wetland Sites (Leonard et al., 1992); 1737-9, Process for Assessing Proper Functioning Condition (Prichard et al., 1993); 1737-10, The Use of Aerial Photography to Manage Riparian-Wetland Areas (Clemmer, 1994 ); and l 737~ 11, Process for Assessing Proper Functioning Condition for Lentic Riparian-Wetland Areas (Prichard et al., 1994).