The Changing Forests of Central Oklahoma: A Look at the Composition of the Cross Timbers Prior to Euro-American Settlement, in the 1950's, and Today

Prior to Euro-American settlement, the Cross Timbers of the Southern Plains marked the edge of “civilization,” beyond which lay a prairie ecosystem ruled primarily by Plains Indian tribes. War, trade, and pasture for cattle brought an increased Euro-American presence by the middle of the 19th century. In the early 1870s a large portion of what was to become the state of Oklahoma was surveyed by the General Land Office (GLO). Although these surveys were not conducted for ecological purposes, they have provided information on pre-settlement vegetation that has been  invaluable for researchers seeking to reconstruct the historical landscape. Perhaps the most beneficial information for historical ecologists and  biogeographers comes from data on bearing trees recorded by GLO  surveyors, which have given present-day researchers a good idea of the species composition of Cross Timbers forests during this time. When  compared to modern studies of the Cross Timbers, it documents a change in species composition over time, believed to be the result of fire suppression and perhaps the beginning of a wetter climate cycle. In central Oklahoma, this has meant a shift from forests dominated by Quercus marilandica and Quercus stellata (with the former being more abundant) to forests containing an equal abundance of these two species, and an  increase in Carya texana, Juniperus virginiana, and other mesophytic and invasive woody species.