Central Texas Plateau Habitat Paper.

Russell B. Fox

5/8/99

Location

The Edwards plateau region of Texas occurs between 98 degrees and 103 degrees west longitude and 29 degrees and 32 degrees north latitude in the southwest portion of Texas. This region is bound on the west by the Pecos River. To the north, northwest, and northeast by physical limits of the cretaceous rocks. To the east by the Blackland prairies. The Balcones fault borders it on the south and the southeast. The Rio Grande River helps form the southwestern boundary in Texas of this formation. (Taylor and Smeins, 1997)

The Edwards Plateau region of Texas has been a tall to mid grass prairie that evolved under a fire and drought regime (Taylor and Smeins, 1997). Rough canyon walls provided fire proof breaks for juniper seedlings that could become established in these areas and helped prevent erosion in these highly susceptible to erosion sloped areas. The suppression of fire and an over utilization of the prairies provided for a woody plant invasion by junipers, mesquites, and oaks which quickly propagated the shallow soils covering the limestone base of the plateau (Taylor and Smeins, 1997).

The oaks enlarged their former area into the grasslands providing cover and acorns for the wildlife and the domestic species alike. The mesquites provided cover and beans for forage as well. The junipers are also utilized by animals for forage and cover. The juniper forage value is limited due to chemicals produced in their leaves that make them less conducive to ruminant gut function but their seeds are readily eaten by numerous species of animals. (Charles A. Taylor per personal conversation)

One of the woodland types found on the plateau that has caused the most change in species composition is the juniper woodland (Rollins and Armstrong). There are two main types of juniper found on the plateau, redberry (juniperus pinchotii Sudw. ) and blueberry (ashe) juniper (juniperus ashei). Redberry is the most difficult to control due to its ability to resprout after being top killed (Ueckert et al.).

Redberry juniper occurs from west-central Texas, southeastern Oklahoma, eastern New Mexico, and Coahuila, Mexico (Sullivan,FEIS).

Blueberry juniper occurs in the largest proportion on the Edwards Plateau of west-central Texas but it is also found in southwestern Missouri and Arkansas, the Arbuckle Mountains of southern Oklahoma and in Coahuila, Mexico (Sullivan,FEIS).

Climate of the Edwards Plateau

A representative county in the middle of the plateau is Sutton county Texas.

The only town in the county is Sonora. The county was named after a confederate officer and Texas Ranger, John S. Sutton. Sutton county averages 18 inches of precipitation that falls primarily in rapid cloudbursts in thunderstorms. Due to the intense rainfall of these thunderstorms, runoff and subsequent erosion is common. The yearly average rainfall is highly variable from less than 10 inches in a year to nearly 40 inches in others. Most rainfall occurs from May through October. Precipitation falls as snow, rain, sleet, and in combinations of these with tornadoes being unheard of. All streams in Sutton county are intermittent except for 5 miles of the Llano River, which is feed by springs. Sutton county has 117 days of 58 degrees Celsius (90 degrees F) or higher and 44 days of 0 degrees Celsius (32 degrees F) or less in an average year.

(Wiedenfeld, pages 24, and 30)

Some of the dominant plant species of Sutton county

Of the eight different range sites occurring in Sutton county. These are only a portion of the plant species naturally possessed by the Edwards plateau:

Grasses

1. sideoats grama (Bouteloua curtipendula) 2) little bluestem (Schizachrium scoparium) 3) green sprangletop (Leptochloa dubia) 4) plains lovegrass (Eragrostis) 5) Texas wintergrass (Stipa leucotricha) 6) plains bristlegrass (Setaria macrostachya) 7) tall dropseed (Sporobolus) 8) Nealley grama (Bouteloua) 9)Canada wildrye (Elymus canadensis L.) 10) vine mesquite (Panicum obtusum) 11) indiangrass (Sorghastrum avenaceum) 12) fall witchgrass (Leptoloma cognatum) 13) slim tridens (Tridens muticus) 14) curly mesquite (Panicum obtusum) 15) hairy grama (Bouteloua Hirsuta) 16) perennial threeawn (Aristida purpurascens).

Forbs

1) Englemanndaisy (Engelmannia pinnatifida) 2) Indian mallow (Abutilon Mill.) 3) brush sunflower (Helianthus L.) 4) orange zexmenia (Zexmenia) 5) rough menodora (Menadora H. & B.) 6) gaura (Gaura L.).

Woody Plants

1. live oak (Quercus virginiana) 2) shin oak (Quercus Havardii) 3) skunkbush (Ptelea trifoliata) 4) hackberry (Celtis L.) 5) bumelia (Bumelia Sw.) 6) kidneywood (Eysenhardtia H.B.K.) 7) redbud (Cercis L.) 8) wildplum (Prunus Munsoniana) 9) grape (Vitis L.) 10) flameleafsumac (Rhus L.)

Invaders

1. red grama (Bouteloua trifida) 2) hairy tridens (Tridens R. & S. 3) purple threeawn (Aristida) 4) mealycup sage (Salvia farinacea) 5) silverleaf nightshade (Solanum elaeagnifolium) 6) hoarhound (Marrubium vulgare L.) 7) evax (Evax Gaertn.) 8) sixweeks fescue (Vulpia octoflora) 9) cedar (juniper) trees (Juniperus ashei & Juniperus erythrocarpa) 11) mesquite trees (Prosopis L.)

(Wiedenfeld, pages 10, 11, and 12)

Game Animals of the Edward Plateau

The historical game animals that occurred in the Edwards Plateau were deer, turkeys, squirrels, javelinas (peccaries), quail and pronghorns. Due to the current state of the plateau from lack of a fire regime and overgrazing, pronghorn antelope no longer reside in any great number. Deer, turkey, javelinas, and squirrels are more numerous now than before the settlement of the area. The deer have benefited from the increased cover from the woodlands encroachment that brings with it live oak, cedar thickets, mast-bearing trees and shrubs, and the small clearings in between the thickets. The turkeys enjoy the increased mast-bearing plants and tall trees for roosting that occur along the drainages. Turkeys also need dense ground cover for nesting, which is provided by the brush. The livestock water tanks and stock ponds have also aided the wildlife. Squirrels also benefit from the large trees in the riparian (stream bank) areas and extra acorns. Feral hogs also claim this habitat as well.

(Wiedenfeld, pages 12 and 13)

Non-Game Wildlife of the Edward Plateau

Raccoons, ring tailed cats, bobcats, coyotes, opossums, diamond back rattlesnakes, armadillos, skunks, and road runners find more than adequate food, cover, and space in the Edwards plateau due to the wide variety of grasses, forbs, shrubs, and trees.

(Wiedenfeld, pages 12 and 13)

Just a few of the birds that appreciate the junipers of the Edwards plateau are robins, cedar waxwings (top), cardinals, the endangered golden-cheeked warbler (middle) and black-capped vireo (bottom).

(Rollins and Armstrong)

Dominant land uses of the Edwards Plateau

Historically, man has been using this area for 11,000 years before present as a hunting and gathering society. The native Americans ground and cooked acorns here, burned the range to draw the game to the burn area as well as to drive game past their marksman and into traps. The Spanish explored it and left the natives the horse. The Comanches and Kiowas became the best horseman here and for 200 years dominated the plateau. The horse was their weapon, their mobilization and their currency to buy wives. For the last 150 years the ranching industry has been the driving economy of the plateau with petroleum products being a boost to the economy. Now more that ever before, the wildlife resources are holding the rancher’s heads above water in current drought coupled with livestock process comparable to the great depression. Hunters are bringing bigger amounts of money back into the Edwards Plateau.

(Taylor & Smeins)

Game managers are putting in high fences to grow artificial deer behind and fixing holes in that fence pushed through by feral hogs that enjoy a seasonal diet of acorns, roots, kid goats, lambs, fawns and snakes (Mungall and Sheffield, page 70).

Mungall, Elizabeth Cary, and William J. Sheffield. "Exotics on the Range: A Texas Example." College Station: Texas A & M University Press, 1994.

Rollins, D. and B. Armstrong. 1994. Cedar Through the Eyes of Wildlife. Symp. Juniper pp. 53-60.

Sullivan, Janet. 1993. Juniperus Ashei. In: Fischef, William C., compiler. The Fire Effects Information System (Data base). Missoula, MT:U.S. Department of Agriculture. Forest Service, Intermountain Research Station. Intermountain Fire Science Laboratory. Magnetic Tape reels; 9 track;1600 bpi, ASCII with Common LISP present.

Sullivan, Janet. 1993. Juniperus erythrocarpa. In: Fischef, William C., compiler. The Fire Effects Information System (Data base). Missoula, MT:U.S. Department of Agriculture. Forest Service, Intermountain Research Station. Intermountain Fire Science Laboratory. Magnetic Tape reels; 9 track;1600 bpi, ASCII with Common LISP present.

Taylor, C.A. and F. E. Smeins. 1994.A history of the Land Use of the Edwards Plateau and It’s Effects on the Native Vegetation. Symp. Juniper pp1-8.

Wiedenfeld, C.C. and J.D. Mcandrew.1968. Soil Survey of Sutton County, Texas. United States Department of Agriculture publication.

Ueckert, D. N., S. G. Whisenant, and M. K. Owens 1994. Juniper Control and Management. Symp. Juniper pp. 61-67.

Central Texas - Edwards Plateau