Fire has been a key factor in shaping the ecology of the Greater Yellowstone Area. Native plant species evolved adaptations so that they survive and in some cases flourish after periodic fires. Fire influences ecosystem processes and patterns, such as nutrient cycling and plant community composition and structure. Fire regimes in the western United States changed with the arrival of European and American settlers, whose livestock removed grassy fuels that carried fires and whose roads fragmented the continuity of fire-carrying fuels. Fires that did break out were suppressed to the extent possible. A goal of the National Park Service is to restore fire’s role as a natural process in parks when and where this is feasible.