Fragmentation of habitat is widely acknowledged as detrimental to wildlife and plant species. Landscape analysis is a proven method to identify fragmentation and other agents of change in a given area. Yet landscape analysis is seldom completed prior to initiation of oil and gas projects, despite considerable evidence that oil and gas extraction and transmittal are likely to cause wide-ranging disturbances in the landscape.
We conducted a pilot analysis of the landscape of the existing Big Piney-LaBarge oil and gas field in the Upper Green River Basin of Wyoming, a region where more than 3,000 oil and gas wells have been drilled. We measured the degree of habitat fragmentation of the field using three metrics: linear feature density (primarily roads and pipelines), habitat in the infrastructure effect zone, and the amount of habitat in core areas (interior habitat that is remote from infrastructure).
Our results indicate an overall density of 8.43 miles of roads and pipelines per square mile. This is at least three times greater than road densities on national forests in Wyoming, South Dakota, and Colorado and is “extremely high” based on ratings in the Interior Columbia Basin Ecosystem Management Project.
The overall area of oil and gas infrastructure (roads, pipelines, pads, waste pits, etc.) at Big Piney-LaBarge covers 7 square miles of habitat, or 4% of the study area. But the effect of that infrastructure is much greater. The entire 166-square-mile landscape of the field is within one-half mile of a road, pipeline corridor, well head, retention pond, building, parking lot, or other component of the infrastructure. One hundred and sixty square miles—97% of the landscape—fall within one-quarter mile of the infrastructure. With respect to core area, only 27% of the study area is more than 500 feet from infrastructure, and only 3% is more than one-quarter mile away.
Our results, combined with a review of the scientific literature, suggest that there is no place in the Big Piney-LaBarge field where the greater sage-grouse—a potential candidate for the endangered and threatened species list—would not suffer from the effects of oil and gas extraction. And the vast majority of the study area has road den- sities greater than two miles per square mile, a level estimated to have adverse impacts on elk populations.
Because our results clearly show that oil and gas drilling and extraction cause signif- icant fragmentation of habitat, we recommend that similar spatial analyses be incor- porated into the evaluation and monitoring of the ecological impacts of proposed oil and gas projects.
We also recommend the following standards for incorporation into assessments of all future oil and gas production sites on public lands.
• Generate infrastructure scenarios prior to field development.
• Assemble regional habitat-use data.
• Generate landscape metrics for all infrastructure.
• Integrate results into management plans.
