Национальный парк Великие песчаные дюны Колорадо

American national park in Colorado, United States

Great Sand Dunes National Park and Preserve is an American national park that conserves an area of large sand dunes on the eastern edge of the San Luis Valley, and an adjacent national preserve in the Sangre de Cristo Range, in south central Colorado, United States. A boundary change and redesignation as a national park and preserve was authorized on November 22, 2000, and then established on September 24, 2004. The dunes cover an area of about 30 square miles (78 km2) and are estimated to contain over of sand. Modern American Indian tribes were familiar with the area when Spaniards first arrived in the 17th century. The traditional Ute phrase for the Great Sand Dunes is Saa waap maa nache (sand that moves). Jicarilla Apaches settled in northern New Mexico and called the dunes Sei anyedi (it goes up and down). Blanca Peak, just southeast of the dunes, is one of the four sacred mountains of the Navajo, who call it Sisnaajini (White Shell Mountain). These various tribes collected the inner layers of bark from ponderosa pine trees for use as food and medicine. The people from the Tewa/Tiwa speaking pueblos along the Rio Grande remember a traditional site of great importance located in the valley near the dunes: the lake through which their people emerged into the present world. They call the lake Sip'ophe (Sandy Place Lake), which is thought to be the springs or lakes immediately west of the dune field.—established a ranch and homestead along Medano Creek in 1875, using the old Medano Pass Road to travel to and from their home. The modern unpaved road follows the old route and is open only to four wheel drive, and high clearance vehicles as it passes through deep sand, rises to Medano Pass, and continues east into the Wet Mountain Valley. The Herards grazed and bred cattle in the mountain meadows, raised horses, and established a trout hatchery in the stream. Other families homesteaded near the dunes as well, including the Teofilo Trujillo family whose sheep and cattle ranch in the valley later became part of the Medano–Zapata Ranch, owned by the Nature Conservancy since 1999. The Trujillo's extant homestead and the ruins of a destroyed one were declared a National Historic Landmark in 2004. Frank and Virginia Wellington built a cabin and hand dug the irrigation ditch that parallels Wellington Ditch Trail located south of the park campground. from the floor of the San Luis Valley on the western base of the Sangre de Cristo Range. The dunes cover an area of about 30 square miles (78 km2) and are estimated to contain over of sand. The creation of the San Luis Valley began when the Sangre de Cristo Range was uplifted in the rotation of a large tectonic plate. The San Juan Mountains to the west of the valley were created through extended and dramatic volcanic activity. The San Luis Valley encompasses the area between the two mountain ranges and is roughly the size of the state of Connecticut. Sediments from both mountain ranges filled the deep chasm of the valley, along with huge amounts of water from melting glaciers and rain. The presence of larger rocks along Medano Creek at the base of the dunes, elsewhere on the valley floor, and in buried deposits indicates that some of the sediment has been washed down in torrential flash floods. In 2002, geologists discovered lakebed deposits on hills in the southern part of the valley, confirming theories of a huge lake that once covered much of the San Luis Valley floor. The body of water was named Lake Alamosa after the largest town in the valley. Lake Alamosa suddenly receded after it broke through volcanic deposits in the southern end of the valley. The water then drained through the Rio Grande, likely forming the steep Rio Grande Gorge near Taos, New Mexico. Smaller lakes still covered the valley floor, including two broad lakes on the northeastern side of the valley. Large amounts of sediment from the volcanic San Juan Mountains continued to wash down into these lakes, along with some sand from the Sangre de Cristo Range. Climate change later significantly reduced these lakes, leaving behind the sand sheet. Remnants of these lakes still exist in the form of sabkha wetlands. Magnetite is an oxide of iron which is heavier than the surrounding particles of sand. When overlying sand is removed by wind, magnetite deposits stay in place and are visible as dark patches in the dune field.

Great Sand Dunes National Park and Preserve is located in Saguache and Alamosa Counties, Colorado at approximately 37.75° north latitude and 105.5° west longitude. The national park is located in the San Luis Valley while the national preserve is located to the east in an adjacent section of the Sangre de Cristo Range of the Rocky Mountains. Elevations range from 7515 feet (2291 m) in the valley west of the dunes, to 13604 feet (4146 m) at the summit of Tijeras Peak in the northern part of the preserve. The dunes cover an area of about 30 square miles (78 km2) while the surrounding relatively flat sand sheet which feeds the large dunes is actually the largest component of the entire dunes system, containing about 90% of all the sand in the park. The Rio Grande National Forest is located to the north and southeast while the remaining forested slopes directly to the east of the dunes were redesignated the Great Sand Dunes National Preserve. The San Isabel National Forest is located to the east of the preserve just beyond the ridge of the Sangre de Cristo Range. Private property abuts most of the southern boundary of the park. The San Luis Lakes State Wildlife Area lies adjacent to the southwestern corner of the park, while the Rio Grande flows through the valley farther to the southwest. The Baca National Wildlife Refuge lies adjacent to the west, and the slopes of the San Juan Mountains begin at the western edge of the valley. Private property of the Baca Grande subdivision of Crestone lies adjacent to the northwest. The nearest towns are Crestone to the north, Mosca and Hooper to the west, Blanca and Fort Garland to the south, and Gardner to the east. Colorado Springs and Denver are located a few hours away by car to the northeast. while the mountainous preserve's climate type is warm summer humid continental (Dfb), at an average elevation of 3343.66 m. Summer high temperatures are moderate with an average high temperature slightly above in July, which is the warmest month. The park's large spread between high and low temperatures, about , is typical of a high desert climate. Low temperatures during winter nights can be extremely cold, with average low temperatures well below and record low temperatures below from November through April. Precipitation is very low on the dunes, averaging just of rainfall per year. A high evaporation rate on the dunes qualifies the area as a desert, even though precipitation exceeds
Spring conditions vary greatly, from mild and sunny to cold and snowy, with occasional high winds in the afternoon. March is the snowiest month, though some days are above In late spring, when Medano Creek usually has its peak flow, snow, and high winds are still possible. In summer, daytime high temperatures average ; however, sand surface temperatures can soar to on sunny afternoons. Summer nights are cool—the park is located 8200 feet (2499 m) above sea level—with nighttime temperatures often dropping below Afternoon thundershowers are common in July and August with cool winds, heavy rain, and lightning. Fall is generally mild, with Indian summer days when temperatures reach or exceed , but nighttime temperatures drop below freezing. Occasional fall storms bring icy rain or snow. Cold temperatures well below freezing are typical in winter, although the sunshine is generally abundant and the dry air does not feel as cold as more humid areas. The average winter high temperatures are just above freezing even in January, which is the coldest month.

The four primary components of the Great Sand Dunes system are the mountain watershed, the dune field, the sand sheet, and the sabkha. The mountain watershed receives heavy snow and rain which feeds creeks that flow down from alpine tundra and lakes, through subalpine and montane woodlands, and finally around the main dunefield. Sand that has blown from the valley floor is captured in streams and carried back toward the valley. As creeks disappear into the valley floor, the sand is picked up and carried to the dune field once again. The recycling action of water and wind, along with a 7% moisture content below the dry surface holding the sand together, contributes to the great height of the dunes. Among the flowering plants are alpine phlox, dwarf clover, alpine forget me not, fairy primrose, alpine aven, paintbrush flowers, lousewort, blue purple penstemon, aspen daisy, western paintbrush, elephantella, snow buttercups, scurfpea, Indian ricegrass, blowout grass, prairie sunflower, Rocky Mountain beeplant, rubber rabbitbrush, speargrass, small flowered sand verbena, narrowleaf yucca, prickly pear cactus, Rocky Mountain iris, and white water buttercup. More than 2000 bison are ranched within park boundaries on private land, owned by The Nature Conservancy, that is closed to the public. More than 250 species of birds have been documented in the park and preserve. Many species nest in the mountains, forests, grasslands, or wetlands during the summer. From higher to lower elevations, and dependent on season, some of the bird species include the brown capped rosy finch, white tailed ptarmigan, red breasted nuthatch, peregrine falcon, mountain bluebird, northern pygmy owl, dusky grouse, hummingbird (four species), western tanager, burrowing owl, bald eagle, golden eagle, sandhill crane, American avocet, and great blue heron. Various reptiles live in the park, such as the short horned lizard, fence lizard, many lined skink, bullsnake, and garter snake. Fish living in the park's streams include the Rio Grande cutthroat trout, Rio Grande sucker (Catostomus plebeius), and fathead minnow. Amphibians include the tiger salamander, chorus frog, northern leopard frog, spadefoot toad, Great Plains toad, and Woodhouse's toad. The park harbors several endemic insects including the Great Sand Dunes tiger beetle, a circus beetle (Eleodes hirtipennis), Werner's (Amblyderus werneri) and Triplehorn's (Amblyderus triplehorni) ant like flower beetle, as well as undescribed species of clown beetle, noctuid moth, and robber fly. More than a thousand different kinds of arthropods have been found at the Great Sand Dunes.

Alpine tundra is the highest elevation ecosystem at Great Sand Dunes where the conditions are too harsh for trees to survive, but wildflowers, pikas, yellow bellied marmots, ptarmigans, and bighorn sheep thrive. The tundra begins about 11700 feet (3566 m) and continues upward to the highest peaks in the park. At subalpine elevations near the tree line grow krummholz (meaning "crooked wood")—trees that are stunted and twisted due to high winds, snow, ice, short growing seasons, and shallow, poorly developed soils. The transition zone between the subalpine forest and alpine tundra is an important refuge during storms for some mammals and birds who primarily live in the tundra. Bristlecone and limber pines grow at an extremely slow rate, with small statures that belie their true ages as some are more than a thousand years old. Medano Creek, which borders the east side of the dunes, never finds a permanent and stable streambed as fresh sand falls in the creek. Small underwater sand ridges that act like dams form and break down, creating surges of water that resemble waves. The surges occur at an average interval of about 20 seconds. In a high water year, the surges can be as high as The "surge flow" mainly occurs during the peak flow period from late May to early June in most years. Big Spring Creek is a unique spring fed creek formed by an unconfined aquifer that creates wetlands that support rare species and plant communities in a generally arid area. The creek was designated a National Natural Landmark in 2012.

The dunes and surrounding area were designated a national monument in 1932 after a bill—sponsored by the P. E. O. Sisterhood and widely supported by local residents—was signed into law by President Herbert Hoover. In 1976, the U. S. Congress designated the Great Sand Dunes Wilderness—a wilderness area encompassing within the monument. This wilderness is the only one in the U. S. that protects a saltbush greasewood ecosystem and includes the entire dune field as well as much of the area west of the dunes. Congress also designated the Sangre de Cristo Wilderness in 1993, which contains a total of of mountainous terrain. Most of the Sangre de Cristo Wilderness is managed by the U. S. Forest Service while the National Park Service manages the area that has since been designated a national preserve. Mechanized transport and motorized equipment or vehicles are not permitted in wilderness areas, while ATVs are not permitted anywhere in the national park and preserve. Both of the wilderness area designations exclude the existing road corridors that pass through them, specifically the paved park road and the unpaved Medano Pass Road. In 1999, the Nature Conservancy purchased surrounding state owned land. The land is within the Medano–Zapata Ranch, located to the west and south. Some of the ranch lands are located within the current national park boundary in its southwestern corner, The objective of the Nature Conservancy, as well as the federal and state governments, is to combine conservation and sustainable use of the ecosystem, like the protected area mosaic recommended in the early 1980s for parts of the Yukon in Canada. The eventual redesignation as Great Sand Dunes National Park and Preserve was authorized on November 22, 2000, when President Bill Clinton signed the Congressionally approved Great Sand Dunes National Park and Preserve Act. The act directed the Secretary of the Interior to "establish the Great Sand Dunes National Park when sufficient land having sufficient diversity of resources has been acquired to warrant its designation." The new designation as a national park and preserve was made official in September 2004 after sufficient land had been acquired, quadrupling its size. In 2002, the Nature Conservancy purchased the Baca Ranch—an area of —for $31.28 million. Financing was provided by the Department of the Interior, the Colorado State Land Board, and private donors. The Baca Ranch had property located in the valley and the adjacent mountains, ranging in elevation from 7500 feet (2286 m) west of the dunes to the 14165 feet (4317 m) summit of Kit Carson Peak. The purchase approximately tripled the size of the monument. The ranch was split into three sections: the Sangre de Cristos section east of Crestone became part of the Rio Grande National Forest; the section west of the dunes was designated the Baca National Wildlife Refuge and managed by the Fish and Wildlife Service; the section east of the dunes was transferred first to the Rio Grande National Forest and later redesignated a national preserve in 2004 managed by the National Park Service. The national preserve remains open to regulated seasonal hunting, as it was when designated national forest land, but is protected from logging and mining activities which are generally permitted in national forests. In 2016, the federal government began negotiations toward purchasing of the Medano–Zapata Ranch from the Nature Conservancy. The plan is to complete the park, making it fully accessible to the public, by acquiring the final piece of privately held land located within the current park boundaries. The land includes the area presently occupied by the bison herd, as well as adjacent meadows and wetland areas.