Chapter 3: Changes to the Wyoming Basins Landscape from Oil and Natural Gas Development

Oil and natural gas have been produced in Wyoming since the late 1800s although the rate of extraction has increased substantially in the last two de- cades. Well pads, roads, and infrastruc- ture built to support resource develop- ment alter native vegetation configuration; however, the rate and effect of land cover change resulting from oil and gas extrac- tion has not been quantified across the region. We used a Geographic Informa- tion System (GIS) to model development through time and assess change to native vegetation at two spatial extents (field and subbasin) within the Wyoming portion of the Wyoming Basins Ecoregional Assess- ment (WBEA) area. Since 1900, a mini- mum of 1,703 km 2 of native vegetation in the WBEA area has been replaced by well pads or roads. Shrublands were, and con- tinue to be, the dominant land cover class and the cover type most affected by oil and gas extraction. Average shrubland patch size has decreased by approximately 10% at the subbasin extent in the WBEA. Core area (60 m from edge) size declined by 13% as road development fragmented for- merly continuous patches. To date, the ma- jority of land cover change has occurred in formally identified oil and gas fields, which cover about 1% of the WBEA in Wyo- ming. Approximately 7.5% of shrubland within oil and gas fields has been convert- ed to well pad or a road supporting a well, and shrubland patch size has declined by 45%. Resource reserves, especially natu- ral gas, have been identified outside tradi- tional fields, and development will likely expand as resource development becomes more cost-effective. Revegetation guide- lines are in place for development areas addressed by Environmental Impact As- sessments although no quantitative data are available to assess how well restora- tion efforts are restoring landscapes and connecting fragments.