Repeat Photography in the Ancient Cross Timbers of Oklahoma, USA

The Cross Timbers form the broad ecotone between the eastern deciduous forest and the grasslands of the southern Great Plains. Forests in the Cross Timbers are dominated by low stature, non-commercial oaks that have not been systematically logged and may be one of the least disturbed forest types in the eastern United States. Here we used long-term repeat photography to document 20th century landscape change in the Cross Timbers, highlighting the persistence of old-growth forest on steep uplands. We repeated 23 historical (1902-1934) landscape photographs of the Oklahoma Cross Timbers from the U.S. Geological Survey's photographic archive in this study. We also investigated the modern forest conditions to identify the presence of old growth. The four photographic pairs presented here do not fully represent the 20th century history of vegetation change in Oklahoma, but these figures vividly illustrate some of the major landcover changes in this forest prairie ecotone: (1) many pre-settlement old-growth forest remnants survive on rugged escarpments in this region, (2) large reservoir projects on the Arkansas, Cimarrón, Canadian, and other rivers have inundated vast areas of farm and rangelands, and (3) some range grasslands are being invaded by woody plants. This repeat photography study provides compelling visual evidence for the survival of ancient forest remnants in the Cross Timbers of Oklahoma.