The Human Footprint in the West

Humans have dramatically altered wildlands in the western United States over the past 100 years by using these lands and the resources they provide. Anthropogenic changes to the landscape, such as urban expansion, construction of roads, power lines, and other networks and land uses necessary to maintain human populations influence the number and kinds of plants and wildlife that remain. We developed the map of the human footprint for the western United States from an analysis of 14 landscape structure and anthropogenic features: human habitation, interstate highways, federal and state highways, secondary roads, railroads, irrigation canals, power lines, linear feature densities, agricultural land, campgrounds, highway rest stops, land fills, oil and gas development, and human induced fires. We used these input layers to develop seven models to estimate the total influence of the human footprint. These models either explored how anthropogenic features influence wildlife populations via changes in habitat (road-induced dispersal of invasive plants, oil and gas developments, human induced fires, and anthropogenic habitat fragmentation) or predators densities (spatial distribution of domestic and synanthropic avian predators). The human footprint map is a composite of these seven models. The final map consists of a 180 meter resolution raster data set with 10 human footprint classes.