Introduction: A Brief History of Repeat Photography

Robert H. Webb, Raymond M. Turner, and Diane E. Boyer

Repeat photography is a valuable tool for evaluating long-term ecological and/or geological change in landscapes. Its practitioners conduct repeat photography projects by acquiring historical and current images, matching those images, and then cataloging and archiving the imagery for long-term storage. The roots of repeat photography lie in the Alps of central Europe, but its uses have spread worldwide, as illustrated throughout this book. Originally developed as a means for documenting changes in glaciers, repeat photography now is used to document all manner of landscape change and ecosystem processes.

Most repeat photography projects have been ad hoc efforts to meet specific needs, such as documenting ecological change in a national park (Meagher and Houston 1998) or a larger ecoregion (Turner et al. 2003). Few efforts have attempted to collate images for collective current or future research use (Bierman et al. 2005). The Desert Laboratory Repeat Photography Collection, named for the Desert Laboratory research facility in Tucson, Arizona, is the largest such collection in the world (Webb et al. 2007a), with over 4,900 camera stations located throughout the southwestern United States, northern Mexico (fig. 1.1), and Kenya. We present a general history of repeat photography as well as a more detailed one of the Desert Laboratory Collection to illustrate the development of this technique and some future trends in its application.

History of Repeat Photography

In its infancy, photography had a documentary purpose, whether it was to record news events, capture the brutality of war, or preserve images of famous people. Scientific photographic documentation in the western United States began with surveys used to determine appropriate routes for the ;transcontinental railways (Bell 1869), to illustrate geological features of landscapes (Powell 1895), or to show the condition of lands prior to development (e.g., George Roskruge; see Turner et al. 2003). The imagery of many of these initial photographic surveys was preserved in archives, making it available to future generations for the study of landscape change.

The Initial Science Applications

A Bavarian mathematician with a geological interest took the first steps in the development of repeat photography as a scientific tool. In 1888, Sebastian Finsterwalder began conducting ;photogrammetric surveys of mountain glaciers in the Tyrolean Alps. He returned to his established camera stations the following year, obtaining repeated images of the same view. By comparing the old and new images, and using rudimentary photogrammetry, Finsterwalder documented change to the glaciers over time (HatterslySmith 1966). In doing so, he pioneered the technique of repeat photography involving deliberate and careful matching of older photographs with newer photographs from the same camera station (Rogers et al. 1984). Following Finsterwalder, early glaciologists in the Canadian Rockies (Cavell 1983), the Sierra Nevada in California (Gilbert 1904), and Alaska (Molnia, chapter 6) used repeat photography as well, establishing the groundwork for a technique that has grown in importance in glaciology (Molnia, chapter 6; Fagre and McKeon, chapter 7).

In addition to its use in glaciology studies, repeat photography soon was used to document plant populations and landscape change. As early as 1905, ecological texts recommended using matched photographs on research quadrats as an aid to plant population measurements (Clements 1905). One of the earliest studies documented decline in rangeland species between 1903 and 1913 on the Santa Rita Experimental Range south of Tucson (Wooten 1916; see McClaran et al., chapter 12). Forrest Shreve, a pioneering desert ecologist, used repeat photography to document changes in vegetation plots at the Desert Laboratory in Tucson between 1906 and 1928 (Shreve 1929). Before the 1940s, only a few studies used repeat photography to document ecological changes in the southwestern United States (Rogers et al. 1984); most of these were narrowly focused and published in scientific journals or monographs.

In the 1940s, repeat photography became a technique frequently used to document landscape change, particularly changes induced by land use. For example, in 1946, repeat photography was used to demonstrate an increase in Prosopis velutina (velvet...