Steve Hallgren Department: Natural Resource Ecology and Management 008 Ag Hall Oklahoma State University Stillwater, OK 74078 steve.hallgren@okstate.edu
The LBJ National Grassland (LBJ) is one of two recommended core wildland sites for the Southern Plains domain (Domain #11). The LBJ Grasslands cover 20,313 acres in north central Texas. They were purchased by the federal government in the late 1930s and they have been managed by the USDA Forest Service since 1955. The primary vegetation of this area is Cross Timbers Forest which is a mosaic of of tallgrass prairie, oak savannah and forest. The dominant forest trees are Quercus stellata Wang. and Q. marilandica Muenchh.. Important grass species include Andropogon scoparius Michx, Andropogon gerardi Vitman, Sorghastrum nutans (L.) Nash, and Panicum virgatum L. Climatically, the LBJ is located near the center of the climate space described for the domain (Figure 1), which is characterized by steep, orthogonal gradients of temperature and precipitation.
The LBJ grasslands are located in a central geographic point within the domain as well, allowing for ready access by scientists from both Texas and Oklahoma. Located near the rapidly growing metroplex of Dallas/Fort Worth, there is ready access to the site. In addition, the Cross Timbers vegetation defines the ecotone between grasslands and forests in the domain which represents a zone that is sensitive to pending climate change. Further, the soils found on the LBJ are in the two dominant soil types found within the entire domain (Alfisols and Mollisols).
The LBJ represents one of the few high quality natural areas that exist within a domain dominated by private land ownership. There is a rich legacy of land use and ecological data, as well as records of prescribed fire and grazing. Fire and grazing have historically been an integral part of these grasslands and savannas so their continued occurrence is necessary to maintain grassland and savanna vegetation and the associated fauna. Thus, these disturbance regimes maintain the wildland characteristic of this site rather than diminishing it.
There are no naturally occurring lakes within the boundaries of the Southern Plains domain. Therefore hydrological research must include work on man-made reservoirs and ponds. There are a number of lakes and ponds on the LBJ of different sizes. The largest are all enclosed by Federal land and are used primarily for recreational fishing. In addition, there are no permanent low-order streams in the area. Many of those streams can dry during severe droughts, including the one experienced during the past 2 years. However, immediately downstream from the dams of these larger lakes, there is permanent stream flow and hydrological research can occur in these areas. In addition, the site is underlain by substantial groundwater resources.
The landscape of the LBJ consists of gently rolling hills typically found in the Red Bed Plains region of Oklahoma and Texas. There are a number of flat, open spaces upon which BioMesoNet towers can be placed. There is ready access to power, but there are no existing buildings for housing or laboratories. Long-term special use permits with the USDA Forest Service can assure long-term access and use of the site by NEON with little or no conflict with current land usages in the area.