The predominant tree in Yellowstone, the lodgepole pine, fared poorly from the fires, except in areas where the heat and flames were very mild. The lodgepole pine is serotinous and often produces pine cones that remain closed and will not disperse seeds unless subjected to fire. Research of test plots established after the fires indicated that the best seed dispersal occurred in areas which had experienced severe ground fires, and that seed dispersal was lowest in areas which had only minor surface burns. Regions with crown fires sometimes had the highest rates of regeneration of lodgepole pine after 5 years. However, the rate of lodgepole regeneration was not uniform, with some areas seeing extremely high densities of new growth while other areas had less. Stands of dead lodgepole killed by the fires may persist for decades, rising above new growth and providing habitat for birds and other wildlife.