Although wildfire is a natural part of the ecosystem of western forests, fire suppression began to be widespread in the late 19th century just as land-use patterns (e.g. intensive grazing) limited the cover that had formerly sustained and been sustained by low-intensity ground fires. High-density stands of small trees and thick underbrush permitted a natural periodic ground fire to leap into a high-intensity crown fire. There followed a century of fire suppression, during which large fires occurred on the Pajarito Plateau about every 20 years: an 1896 fire, several fires in the 1920s, a fire in 1946, the 1954 Water Canyon Fire, the 1977 La Mesa Fire, and the 1996 Dome Fire.