Crosstimbers Oak Forest and Woodland

This vegetation type is a relatively uncommon component of the system, generally occurring in the eastern Crosstimbers on calcareous substrates. Overstory is dominated by Quercus fusiformis (plateau live oak), with Quercus stellata (post oak), Ulmus crassifolia (cedar elm), Prosopis glandulosa (mesquite), and Juniperus ashei (Ashe juniper) also present as minor components of the canopy. In some areas it may be difficult to distinguish occurrences of this vegetation type from occurrences of Edwards Plateau Limestone Savanna and Woodland (CES303.660) representing outliers of that system.

Distribution Map

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Public Land Occurrence

• None.

Sites co-dominated by Juniperus species (Juniperus virginiana (eastern redcedar) to the north and east, and Juniperus pinchotii (redberry juniper) and Juniperus ashei (Ashe juniper) elsewhere are frequently encountered. Such sites, thought to result from disruption in the fire regime, may have Quercus stellata (post oak) and Quercus marilandica (blackjack oak) as co-dominants in the canopy. The dense canopy cover by cedars often results in limited light penetration and the consequent reduction in herbaceous cover. In central and southern portions of the Crosstimbers, areas over limestone substrate that are mapped as this type may be dominated by Quercus buckleyi (Texas oak), Quercus fusiformis (plateau live oak), and Juniperus ashei (Ashe juniper). Ulmus crassifolia (cedar elm) and Celtis laevigata (sugar hackberry) may also be important canopy species.

Distribution Map

Photos

Public Land Occurrence

• Caddo National Grasslands – Lake Fannin: US Forest Service
• Hagerman National Wildlife Refuge: U. S. Fish and Wildlife Service
• Ham Creek Park: City of Blum
• Lake Whitney Recreation Area: US Army Corps of Engineers
• Ray Roberts Lake Wildlife Management Area: Texas Parks & Wildlife Department

This vegetation type represents the typical occurrence dominated by the usual Quercus stellata (post oak) and Quercus marilandica (blackjack oak), with other canopy species such as Carya texana (black hickory), Ulmus crassifolia (cedar elm), Quercus fusiformis (plateau live oak), Juniperus virginiana (eastern redcedar), and Celtis laevigata (sugar hackberry) present. The overstory may be relatively closed, resulting in reduced herbaceous cover. In some situations, Prosopis glandulosa (mesquite) may be relatively dense. Grass species, particularly Schizachyrium scoparium (little bluestem), are present in the understory, and may form prairie openings in the woodland.

Distribution Map

Photos

Public Land Occurrence

• Aquilla Lake Recreation Area: US Army Corps of Engineers
• Fort Worth Nature Center: Tarrant County
• Grapevine Lake Recreation Area: US Army Corps of Engineers
• Hagerman National Wildlife Refuge: U. S. Fish and Wildlife Service
• Lake Lewisville Recreation Area: US Army Corps of Engineers
• Lake Mineral Wells State Park: Texas Parks & Wildlife Department
• Lake Whitney Recreation Area: US Army Corps of Engineers

This is a primarily herbaceous vegetation type, representing the graminoid dominated component of the savanna as it occurs within this system. Occurrences tend to occur on tighter soils (such as on Clay Loam, Clayey Upland, Claypan Prairie, and Claypan Savanna ecoclasses), but are often dependant on appropriate land management (such as prescribed fire and/or brush control) that ensures reduced woody cover. Woody canopy represents less than 25% cover. Historically, Schizachyrium scoparium (little bluestem) likely dominated these grasslands, but current composition may be largely determined by landuse history and grazing pressure. In the east, where precipitation is greater, tallgrass species such as Andropogon gerardii (big bluestem) and Sorghastrum nutans (Indiangrass) may be important components. In the drier west, shortgrass species such as Buchloe dactyloides (buffalograss) become more conspicuous. Other graminoid species that may be present include Schizachyrium scoparium (little bluestem), Nassella leucotricha (Texas wintergrass), Paspalum setaceum (fringeleaf paspalum), Sporobolus compositus (tall dropseed), Bouteloua curtipendula (sideoats grama), Bouteloua hirsuta (hairy grama), Bouteloua rigidiseta (Texas grama), Bothriochloa laguroides ssp. torreyana (silver bluestem), and Aristida spp. (threeawn). Non-native species such as Cynodon dactylon (bermudagrass), Bromus arvensis (Japanese brome), Bromus tectorum (cheatgrass), and Bothriochloa ischaemum var. songarica (King Ranch bluestem) are often significant components. It may be difficult to distinguish occurrences of this vegetation type from occurrences of Southeastern Great Plains Tallgrass Prairie (CES205.685) to the east and Central Mixedgrass Prairie (CES303.659) to the west. Prosopis glandulosa (mesquite) is a common shrub in this type, and some areas have fairly dense mesquite cover.

Distribution Map

Photos

Public Land Occurrence

• Aquilla Lake Recreation Area: US Army Corps of Engineers
• Fort Worth Nature Center: Tarrant County
• Hagerman National Wildlife Refuge: U. S. Fish and Wildlife Service
• Lake Lewisville Recreation Area: US Army Corps of Engineers
• Ray Roberts Lake Wildlife Management Area: Texas Parks & Wildlife Department

This is a very minor component of the system, occupying slopes greater than twenty percent and dominated by Juniperus ashei (Ashe juniper), Juniperus virginiana (eastern redcedar), or less commonly, Juniperus pinchotii (redberry juniper). This vegetation type is mapped in the southern part of the Western Crosstimbers, where it is frequently associated with slopes on calcareous substrates. These occurrences might be more appropriately considered outliers of Edwards Plateau: Ashe Juniper Slope Forest.

Distribution Map

Photos

Public Land Occurrence

• Lake Mineral Wells State Park: Texas Parks and Wildlife Department
• Lake Whitney Recreation Area: U. S. Corps of Engineers

Forests occupying slopes greater than twenty percent with canopies co-dominated by deciduous hardwood species (such as Quercus stellata (post oak), Quercus buckleyi (Texas oak), Quercus marilandica (blackjack oak), Ulmus crassifolia (cedar elm)) and juniper species (including Juniperus pinchotii (redberry juniper), J. virginiana (eastern redcedar), or J. ashei (Ashe juniper), depending on the site). On some mesic slopes on limestones or chalks of the northern Crosstimbers, and into the Blackland Prairie, Quercus shumardii (Shumard oak) and Quercus muehlenbergii (chinkapin oak) may become the co-dominants in the vegetation type. The overstory canopy tends to be more closed than the upland counterparts, and shrub and herbaceous cover is consequently reduced. Occurrences of this type in the southern part of the Western Crosstimbers frequently occupy slopes on calcareous substrates and may be more appropriately considered as Edwards Plateau Slope forest.

Distribution Map

Photos

Public Land Occurrence

• Lake Mineral Wells State Park: Texas Parks and Wildlife Department
• Lake Whitney Recreation Area: US Army Corps of Engineers

These relatively closed canopy forests on slopes (greater than twenty percent) are dominated in the overstory by deciduous species, primarily oaks such as Quercus stellata (post oak), Quercus muehlenbergii (chinkapin oak), Quercus marilandica (blackjack oak), Quercus buckleyi (Texas oak). Ulmus crassifolia (cedar elm), Sideroxylon lanuginosum (gum bumelia), Celtis laevigata (sugar hackberry), and/or Celtis laevigata var. reticulata (netleaf hackberry) may also be common in the canopy. These slopes are frequently associated with the Sandstone Hill, Bouldery Hill, or Rocky Hill ecoclasses, with the substrate often derived from underlying sandstones. Evergreen species such as Quercus fusiformis (plateau live oak) and Juniperus spp. (juniper) may be present, but relatively minor components. On some calcareous slope in the northern part of the Crosstimbers, and into the Blackland Prairie region, Quercus shumardii (Shumard oak) and Quercus muehlenbergii (chinkapin oak) may dominate or co-dominate, with Quercus muehlenbergii (chinkapin oak) tending to dominate drier sites and Quercus shumardii (Shumard oak) dominating more mesic sites. On such mesic sites dominated by Quercus shumardii (Shumard oak), subdominants may include Quercus muehlenbergii (chinkapin oak), Quercus macrocarpa (bur oak), Celtis spp. (hackberry), and Ulmus rubra (slippery elm). 

Distribution Map

Photos

Public Land Occurrence

• Fort Worth Nature Center: Tarrant County
• Grapevine Lake Recreation Area: US Army Corps of Engineers
• Lake Brownwood State Park: Texas Parks & Wildlife Department
• Lake Lewisville Recreation Area: US Army Corps of Engineers
• Lake Mineral Wells State Park: Texas Parks & Wildlife Department
• LBJ National Grassland, Cross Timbers Research Natural Area: US Forest Service
• Ray Roberts Lake Wildlife Management Area: Texas Parks & Wildlife Department

This vegetation type represents system occurrences that occupy particularly sandy sites (typically Deep Sand, Sand Hill, and perhaps some Sandy ecoclasses), often associated with Paluxy and Antlers Sand or alluvial or eolian deposits. Differentiation of this vegetation type is currently theoretical in anticipation that these sites may be sufficiently distinct to require a separate vegetation type, however field data is largely lacking. These sites are likely dominated by Quercus stellata (post oak) and Quercus marilandica (blackjack oak). Quercus margarettae (sand post oak) may be present in this vegetation type, and sites should be sampled to verify, especially in Eastland and Comanche counties on Antlers Sand or sandstone members of the Twin Mountains Formation. Carya texana (black hickory), Ulmus crassifolia (cedar elm), and Celtis laevigata (sugar hackberry) may be well-represented in the overstory.

Distribution Map

Photos

Public Land Occurrence

• Fort Worth Nature Center: Tarrant County
• Lake Whitney State Park: Texas Parks and Wildlife Department
• LBJ National Grassland, Cross Timbers Research Natural Area: U. S. Forest Service