Lyndon B. Johnson National Grassland NEON / CLBJ

Caddo – Lyndon B. Johnson National Grasslands (CLBJ) is a terrestrial NEON field site located in the Great Plains region of north-central Texas, about 50 km (30 mi.) northwest of Denton. CLBJ occupies approximately 80 km² (20,000 acres) of public lands managed by the U.S. Forest Service. NEON samples 41.9 km² (10,300 acres) of area at CLBJ. The site has fairly flat terrain and consists of a mosaic of oak-dominated forests and grasslands. CLBJ is part of NEON's Southern Plains Domain (D11), which stretches over the central sections of Texas and Oklahoma and includes portions of southern Kansas and southern New Mexico. D11 has three other NEON field sites, including one additional terrestrial and two aquatic sites, located in Texas and Oklahoma. CLBJ is colocated with the Pringle Creek (PRIN) aquatic field site. [1] [3]

The climate of CLBJ is typical of Northeast Texas, with hot, humid summers and cool, windy winters. Mean annual temperature is 17.5°C (63.5°F) and mean annual precipitation is 898 mm (35.4 in.), falling mostly from mid-April to late June. Violent thunderstorms over the southern plains - some of which produce high winds, hail, and tornadoes - provide much of the region’s spring rainfall. [6] [7]

The underlying geology of CLBJ is primarily interbedded sandstone and siltstone of the Antlers Sand Formation; some residuum and colluvium are derived from calcareous limestone of the Walnut Clay Formation and local alluvium. The region’s topography rolling and hilly due to differential erosion, becoming more rugged in the west. [2] [4] [5]

CLBJ soils are Udic Paleustalfs, according to the USGS Mineral Resources Database Duffau, Weatherford, Keeter, Pidcoke, Wise and Windthorst soils are all present at the site; Duffau and Windthorst are the most common, although Windthorst is considered transitional between Duffau and Weatherford. High-clay soils can inhibit tree growth due to low permeability. [4] [5]

The Caddo-LBJ National Grasslands has fairly flat terrain and consists of a mosaic of oak-dominated forest and grasslands. The dominant canopy species at CLBJ are post oak (Quercus stellate) and blackjack oak (Q. marilandica). Important grass species include little bluestem (Schizachyrium scoparium), big bluestem (Andropogon gerardi), Indiangrass (Sorghastrum nutans), and switchgrass (Panicum virgatum). [1] [8]

CLBJ’s grasslands provide a diverse habitat for a variety of species, including white-tailed deer (Odocoileus virginianus), coyotes (Canis latrans), bobcats (Lynx rufus), red fox (Vulpes vulpes), bobwhite quail (Colinus virginianus), and turkey. The grasslands also host numerous small mammals, songbirds, and waterfowl, including the endangered Least Tern (Sternula antillarum athalassos). The threatened timber rattlesnake (Crotalus horridus) and Texas horned lizard (Phrynosoma corunutum) can also be found in the region. [3] [9] [10] [11]

Historically, the Caddo – LBJ National Grasslands were a large woodland area bordered by open prairie to the east and west. European settlers moved into the area in the 1800s under a variety of "Homestead Acts." The settlers fragmented and cleared the land for agricultural activities including grazing, ranching and growing crops. After a prolonged period of drought in the 1920s and 1930s, the U.S. government purchased homesteads experiencing soil erosion problems and returned them to public land status. In the 1950s, these lands were assigned to the U.S. Forest Service, which was tasked with managing and restoring the lands. To prevent further erosion, the U.S. Forest service built water retention levees and dams, creating many small ponds throughout the landscape. Originally, the grasslands were called the "Cross Timbers National Grassland," however, the grasslands were renamed the "Lyndon B. Johnson National Grasslands" in 1974 after the former president. Since that time, the U.S. Forest Service has a focused on "promoting better utilization of the land, providing work in the depressed area, and developing water-oriented recreation facilities." [12] [13] [14]

The Caddo-LBJ National Grasslands is a popular recreation area for hiking, hunting, fishing, and horseback riding. Cattle are grazed on parts of the site. Current management of the grasslands and the surrounding area uses prescribed burn to encourage the growth of natural plant communities and manage the composition of forest stands. Timber harvesting is limited to encourage regeneration; the Forest Service’s current management plan adds approximately 3 km² (700 acres) of regeneration per year. [1] [5]

Plots were established at CLBJ in April 2016. In July 2016, the site underwent a sampling readiness review, and terrestrial observations and sampling began on July 29, 2016.