The land use practices that accompanied settlement across central North America changed the structure and function of the North American tallgrass prairie landscape. Tallgrass prairie vegetation has experienced the largest areal reduction compared to other North American vegetation types. Euro-American settlement over the past 150 years is reported in historical records providing the data to study land use modification in the tallgrass prairie. The decline or loss of tallgrass prairie habitat was also accompanied by habitat fragmentation, a change in the spatial configuration of the original landscape. Land use practices that lead to the loss and fragmentation of tallgrass prairie include conversion to monoculture row crop production, introduction of non-native forage crops, woody plant encroachment, overgrazing, and urban expansion.

This dissertation research used qualitative and quantitative methods to understand how modification in land use from the pre-settlement period to 2008 has altered the tallgrass prairie. In the first chapter I conducted a review of historical agriculture reports to determine when and why the non-native grass tall fescue (Schedonorus phoenix) was introduced into Oklahoma tallgrass prairies. I found that the two primary reasons for introduction were for prevention of soil erosion and to increase forage production, therefore increasing farm profits. In chapter two I used historical spatial data obtained from the General Land Office to determine land use practices that initially altered the tallgrass prairie landscape following settlement. I used spatial data and historic records to reconstruct the tallgrass prairie landscape in northeastern Oklahoma at the time of the Public Land Survey. I determined that the main drivers for loss and fragmentation of the tallgrass prairie vegetation was initiated by opening Indian Territory to railroads and settlers, the invention and widespread use of barbed wire fencing, which allowed for enclosure of, and an increase in cultivated fields, and the allotment of native lands. The third chapter quantified the areal loss and fragmentation of the tallgrass prairie vegetation by comparing tallgrass prairie land cover from pre-settlement, to 1896, to 2008. Landscape metrics were calculated to measure the degree of fragmentation. I found that 85% of the original tallgrass prairie landscape had been lost through land use changes. The tallgrass prairie that remained on the landscape was remnant patches maintained as either rangeland or hay meadows. Hay meadows represent traditional landscapes maintained to produce native prairie hay. These traditional landscapes harbor high species diversity and require little input of labor, fuel or chemicals to maintain them, compared to non-native monoculture pastures. This dissertation project studied land use changes by applying concepts and methods from the fields of geographic information science, biogeography, historical ecology, landscape ecology and conservation biology. The knowledge gained from this dissertation research can be used for the conservation and/or restoration of landscapes fragmented from land use modification.