Long-term data sets are rare but highly valued in ecological sciences. They can provide valuable insight into environmental processes that occur over long-time periods; a perspective not often available with other methods. By comparing historical on-the-ground oblique photos with modern images of the same locations, scientists are able to measure how current environments have either changed or persisted in a similar state over multiple decades, even when there is no official written record for what the landscape looked like in the past. This set of photos was mostly taken by the National Park Service (or acquired from outside visitors) from the early 1900s onward, photographed in and around the four National Parks and Monuments within southeastern Utah. Efforts to recapture the images as closely as possible have been periodically made in the decades since.
Researchers in the National Park Service (NPS) and United States Geological Survey (USGS) have examined the photos taken to start to answer questions about how both natural and human environmental impacts such as drought, grazing, and land preservation have impacted a variety of drylands ecosystems. With photos from as early as the 1910s and as recent as 2015, this collection has documented individual tree growth or death, grasslands turning to shrublands, and the presence of new or invasive species for the locations represented. The visual information within these photos can then also be linked to outside data, such as records of drought years or land ownership changes, so that scientists can piece together an idea of what environmental and other processes may have driven the changes or similarities visible in the photos. This knowledge then can be used to determine how current or future changes in climate and land management may continue to affect the drylands of southeast Utah.