Repeat photographs of Saguaro National Monument East (now Saguaro National Park), Rincon Mountain District, Tucson, AZ, 1935 and 2010
A repeat photographic series of Saguaro National Monument (now Saguaro National Park) East, Rincon Mountain District. The earliest photo, courtesy of the National Park Service (NPS; public domain image) was taken in 1935 of the abundant 'cactus forest' of saguaros (Carnegiea gigantea). According to NPS and USGS research in this area, in 1935 foothills paloverde (Parkinsonia microphylla) and velvet mesquite (Prosopis velutina) trees were scarce since they were harvested during that time period.
The later photograph by Dr. Ray Turner, USGS, taken in 2010 at this same location shows the return of those tree species. Paloverde and mesquite act as 'nurse trees' to young saguaros, providing protection from cold in winters and shade in summer, thereby enabling a stronger chance of saguaro survival during early growth. SBSC Southwest Repeat Photography Collection stake (camera point) s0013.