Tamaulipan Savanna Grassland

Geology

On thinner eolian sands on the western side of the South Texas Sand Sheet, and other sandy sites such as those of the Eocene sands of the Carrizo, Queen City, and Sparta Formations. Also found associated with other formations, such as Oakville Sandstone and other formations producing sandy residuum.

Landform

Level to gently rolling sites.

Soils

Sandy to sandy loam sites, such as those of the Sandy, Loamy Sand and Sandy Loam Ecological Sites.

Parent Description

This system occurs on sandy soils, including sandy, sandy loam, and loamy sands. It is typically dominated by Prosopis glandulosa (honey mesquite) in the overstory, and the overstory may be sparse, giving the aspect of an open grassland, with scattered trees and shrubs. Or, more commonly, the system occurs as shrub-dominated patches within a grassy matrix, with an emergent canopy to about 6 or more meters in height of Prosopis glandulosa (honey mesquite) and sometimes other species, such as Ebenopsis ebano (Texas ebony) or Celtis ehrenbergiana (granjeno). Sometimes the overstory canopy is well-developed and would be considered woodland. These patches often coalesce to form significant expanses of shrubland. Sites with somewhat tighter soils tend to have a denser shrub stratum, while deep sands and sandy sites tend to be more open, often with sizeable areas lacking significant shrub cover and dominated by a primarily graminoid herbaceous layer. The shrub component of woody patches or shrublands is commonly dominated by species such as Zanthoxylum fagara (Colima), Condalia hookeri (brasil), Celtis ehrenbergiana (granjeno), Opuntia engelmannii var. lindheimeri (Lindheimer pricklypear), Diospyros texana (Texas persimmon), Colubrina texensis (Texas hogplum), Cylindropuntia leptocaulis (tasajillo), and Acacia farnesiana (huisache). Prosopis glandulosa (honey mesquite) is almost always present, and is often dominant to co-dominant and occupies the highest canopy position (sometimes sharing that position with few other species), sometimes to 6 m in height. Numerous other species may also occur in the shrub layer, including but not limited to Schaefferia cuneifolia (desert yaupon), Mahonia trifoliolata (agarito), Forestiera angustifolia (desert olive), Lycium berlandieri (Berlandier wolfberry), Aloysia gratissima (whitebrush), Salvia ballotiflora (shrubby blue sage), and Ziziphus obtusifolia (lotebush). The diversity of the shrub layer is significantly influenced by land use history, with recently cleared areas sometimes being represented by a near monoculture of Prosopis glandulosa (honey mesquite) in the overstory, Pennisetum ciliare (buffelgrass) in the herbaceous layer, and Opuntia engelmannii var. lindheimeri (Lindheimer pricklypear) as the most conspicuous component of the shrub layer. The herbaceous layer is typically dominated by graminoids and may be quite dense (60 to 100% cover). Grasses, such as Schizachyrium scoparium (little bluestem), Schizachyrium littorale (seacoast bluestem), Chloris cucullata (hooded windmillgrass), Paspalum monostachyum (gulfdune paspalum), Paspalum plicatulum (brownseed paspalum), Elionurus tripsacoides (Pan American balsamscale), Bouteloua rigidiseta (Texas grama), Urochloa ciliatissima (fringed signalgrass), Heteropogon contortus (tanglehead), Eragrostis secundiflora (red lovegrass), Bothriochloa laguroides ssp. torreyana (silver bluestem), Trichloris pluriflora (multiflower false Rhodes grass), Aristida spp. (threeawns), Sporobolus cryptandrus (sand dropseed), and/or Dichanthelium spp. (rosette grasses) commonly dominate or co-dominate the herbaceous layer. Forbs are also common, including species such as Gaillardia pulchella (Indian blanket), Eriogonum multiflorum (heartsepal wildbuckwheat), Croton spp. (croton), Cnidoscolus texanus (Texas bull-nettle), Aphanostephus skirrhobasis (lazy daisy), Rudbeckia hirta (blackeyed Susan), Verbesina encelioides (cowpen daisy), Clematis drummondii (old man's beard), Cynanchum barbigerum (bearded shallow-wort), Thymophylla pentachaeta (parralena), Justicia pilosella (hairy tubetongue), Nama jamaicense (fiddleleaf nama), Monarda punctata (spotted beebalm), Palafoxia texana (Texas palafoxia), Florestina tripteris (white palafoxia), Zornia bracteata (bracted zornia), Croptilon divaricatum (scratch-daisy), Rhynchosia americana (American snoutbean), and Wedelia texana (hairy zexmania), though some of these species are restricted to the sandiest sites.