Pawnee National Grassland
Pawnee National Grassland is a United States National Grassland located in northeastern Colorado on the Colorado Eastern Plains. The grassland is located in the South Platte River basin in remote northern and extreme northeastern Weld County between Greeley and Sterling. It comprises two parcels totaling largely between State Highway 14 and the Wyoming border. The larger eastern parcel lies adjacent to the borders of both Nebraska and Wyoming. It is administered in conjunction with the Arapaho-Roosevelt National Forest from the U.S. Forest Service office in Fort Collins, with a local ranger district office in Greeley. The  grassland is in an especially depopulated area of the Great Plains. It saw limited cultivation in the early 20th century but was withdrawn from farming after the Dust Bowl. The communities of Keota and Purcell are located within the grassland. The town of Grover is located directly between the two large parcels of the grasslands near Crow Creek. Briggsdale sits at the southern end where State Highway 14 and State Highway 392 meet. State Highway 71 traverses the eastern unit north of Stoneham. The eastern unit is drained by Pawnee Creek, a tributary of the South Platte. The western unit  is largely drained by Crow Creek. Recreation and access. Camping is available at the Crow Valley Recreation Area northwest of Briggsdale. The grassland contains several hiking trails, including one that allows foot access to the Pawnee Buttes, the most notable geologic feature of the grasslands. Bird watching is a popular recreational activity for day hikers, especially at the Chalk Bluffs, a raptor nesting site. Recreational activities on the Pawnee Grasslands have been somewhat curtailed over the last 10 years due to the discovery of extractable oil and natural gas. According to the US Forest Service, there are 63 active vertical  oil and natural gas wells, and less than 3,000 acres of the 193,060 acres is protected from drilling. Geology. The grasslands is a joining of two soil types. In the east are prairie soils that are deep, and dark or reddish. From the west are chernozems of a chestnut, becoming brown. The chestnut soils are the dominant type across the areas. These soils develop in semiarid climates with of rain annually. They are associated with buffalo grass and blue grama. Around the buttes, the soils are most likely brown soils which are characteristic of cool, semiarid condition and are evidenced  by short grasses and shrubs. Water is available from a Cretaceous period aquifer. Three springs are in the vicinity of the buttes: Nelson Ranch ( north), old Linglebach Homestead ( south), and an arroyo ( west). The main access to the aquifer is by windmill pumps. The aquifer is recharged from the west and flows eastward. There are Tertiary and Quaternary aquifers which are recharged by precipitation and seepage from streams. The Brule Formation, where available provides a large quantity of water. Shortgrass prairie. The grassland is a part of the short grass plains of North America. The best example of this ecosystem  are preserved around the Pawnee Buttes where grazing and intensive agriculture have had less impact. There are eleven vegetation zones represented with the most unique being the scarp woodlands on the north face of the buttes. Typical of higher elevations, there are limber pines and relicts of an ice-age forest. The wildlife of the grasslands is best represented near the buttes, with pronghorn, deer, bison, prairie dog, wolves, coyotes, rabbits, and numerous rodents. Nesting birds include the golden eagle and prairie falcons . Flora. Wildflowers bloom from April through September. The best locations for viewing wildflowers are near rocky outcrops  or wet potholes, such as are found near the Pawnee Buttes.