MANITOU PARK -- Biologist Steve Tapia pointed to an open, park-like grove of mature 80-foot ponderosa pines with scorched trunks and blackened bunchgrasses beneath them, victims of the Hayman Fire. The trees are on the northwestern edge of the Manitou Experimental Forest, where tree-thinning and intentional burning have been practiced for 50 years to maintain forest health and to avoid catastrophic wildfires. On Tuesday, the Hayman Fire burned through the crowns of pines several miles to the west in the West Creek Range, killing large stands of trees. But when the wildfire got down onto the flats of Manitou Park and entered the experimental forest, it dropped to the ground. About one square mile of the 26-square-mile experimental forest burned, Tapia, the resident manager of the U.S. Forest Service research facility, said Thursday. Most of the burning occurred on the ground, killing grasses but sparing the fire-resistant ponderosa, which have a thick, corky bark. "This is what we need to be doing throughout our forests," Tapia said as he pointed out where the southeast edge of the fire crossed the experimental forest before continuing east into the Rampart Range. "Had this forest been denser, it would have gotten up into the crowns, and these would be dead trees -- like those on the ridge," Tapia said, pointing west to the matchstick remains of pines on the West Creek range. The Manitou Experimental Forest is bisected by Trout Creek, a small stream and tributary of the South Platte River. One of the oldest experimental forests in the country, the Manitou was established in 1936 and is used by researchers from across the country. Scientists come here to conduct long-term watershed studies and investigations into the growth and regeneration of ponderosa pines and their ecosystems. The forest is also home to a study of flammulated owls that began in the 1970s. Bill Shepperd, who administers the forest at the Rocky Mountain Research Station in Fort Collins, said the owl study is "one of the longest bird population studies in the world." The forest contains a 25-acre stand of old-growth ponderosa dating back 250 to 400 years. They were spared from the extensive logging that consumed many of the Manitou Park pines in the 1870s. The old-growth plot was saved from Tuesday's explosive eastern fire run, but eight long-term ponderosa regeneration plots were destroyed, Tapia said. In those 100-square-yard plots, researchers compared the growth rate of natural ponderosa seedlings to those that were planted. The experiment, which began 20 years ago, showed that it takes a naturally seeded ponderosa 13 years to reach a height of 18 inches. The slow growth rate is due to long, cold winters and hot, dry summers. "That experiment is over," Tapia said. "We can't collect any more data because we don't have anything more to measure." The experimental forest is 28 miles northwest of Colorado Springs and several miles north of Woodland Park, straddling Highway 67. The research station includes six pink limestone buildings raised by the Works Project Administration during the Depression. Bulldozers have been used to protect the buildings and the forest experiments, and a fire crew is stationed at the limestone structure during the Hayman Fire. Manitou Park itself was a destination tourist attraction in the late 1800s. The founder, Dr. William Bell, built three hotels, a fish hatchery, a logging operation and a dude ranch. All the hotels eventually burned to the ground, Tapia said.