Abstract: Conservation and management of Texas wildlife resources and land-use practices should be based on landscape ecology. Understanding the ecological regions of the state builds the best foundation upon which to base sound decisions. After a discussion of the biodiversity and biogeography of Texas, 1 2 ecological regions are described. Then, trends in land use affecting wildlife resources are discussed.
This introductory chapter is quite general in scope. The references at the end of the chapter will provide specific historical as well as biological information, some of which is extensive.
Texas is located at the crossroads of 4 major physiographic subdivisions of North America—Gulf Coastal Forests and Prairies, Great Western Lower Plains, Great Western High Plains, and the Rocky Mountain Region (Fig. 1). Topographically, with the exclusion of the Rocky Mountain Region west of the Pecos River, the state is a series of descending plains and prairies from northwest to southeast. There are 3 prominent geologic features: western mountains in the Trans-Pecos, the north-south Caprock Escarpment in the Panhandle, and the arcshaped Balcones Escarpment in the central area of the state. The 367 miles of coastline are extensive and diverse. Prior to the 1880's, the central 80% of the state was short to tall grassland, the western 10% across the Pecos River was desert grassland, and the eastern 10% was forest land.
Contemporary landownership patterns reflect the history of the state. Because Texas retained its public lands at the time it entered the United States, the proportion of federal ownership has remained low (1.4%). Political views of Texans have traditionally stressed rights of private landownership. However, in contemporary times, individual small landowners are being joined by large corporate landowners, including foreign investors.
The Texas economy was originally agricultural, major products being cotton, corn, and cattle. Oil discovery in the early 1900's and mineral production assumed an important economic role during the next decades. Agriculture, manufacturing, and mining diversification began about 1940 and led to a high degree of steady economic stability and growth. Shifts of population from rural to urban areas provided sufficient labor markets for industrial development as well as creating area markets. Texas is cited as having the best business climate in the nation and ranks among the top 3 or 4 states in most economic activities.
Texas is the second most populated state. It also ranks as one of the fastest growing states, having an annual growth rate more than twice that of the entire nation.
About 83% of the land in Texas is devoted to agriculture, mostly grazing (61%) and crop production (21%). Although mineral extraction is a major industry, the proportion of land devoted to this use is small. Commercial forestry is located primarily in the East Texas PineHardwood Forests. Texas is also a land of vast recreational opportunities because of its favorable climate and varied topography, vegetation, and wildlife, most of which is provided within the Texas State Parks System and the federal recreational lands of the National Park System, the Forest Service, National Wildlife Refuges, and reservoir lands controlled by the U.S. Army Corps of Engineers.
Texas has a greater variety of wildlife than any other state. However, public and private activities in the state have the potential to cause significant destruction of wildlife habitat, and general trends are evident. Among them are rapid population growth and continued exploitation of natural resources which include water resources development, agricultural practices, forestry practices, mineral and energy production, urban and industrial expansion, recreational or leisure developments, and transportation facilities.
Floral and Faunal Patterns
The great diversity of flora and fauna in Texas (Table I.1) and their patterns of distribution within ecoregions (frontispiece) correlate with a matrix of complex environmental factors involving geology, topography, climatic zones, rainfall belts, and soil types (Tables I.2-I.4). There are 4,834 species of vascular plants, of which 425 (8.8%) are endemic. Nearly half (523) of the grass species indigenous to the United States occur in Texas. There are 247 species of freshwater fishes (14 endemic, 5.7%) and 958 species of terrestrial vertebrates (16 endemic, 1.7%).
Unfortunately, 574 species of vascular plants are introduced (11.9%), as are 42 vertebrate species (3.5%). Fortunately, few species have become extinct or extirpated since the time of Anglo-American settlement (8 fishes, 4 birds, and 9 mammals), but many species are classified as threatened, endangered, or of special concern (Table I.1). Collectively, these include 56 vascular plants (1.2%) and 171 vertebrates (14.2%). See species lists in Appendix D.
The greatest number of species inhabit the Gulf Coast, Trans-Pecos, and eastern forest regions. The area of least diversity is the panhandle (High Plains and Rolling Plains). The largest number of endemic species (both statewide and local) occur in the Trans-Pecos, Edwards Plateau, and South Plains.
In general, species diversity tends to increase from areas of uniform elevation to areas of varied topography, i.e., from the relatively flat, uniform east to the relatively rugged, heterogeneous west. However, fish and amphibian species diversity increases from west to east in response to permanent water and moisture availability.
Maximum fish species diversity corresponds with the location of river drainages (Fig. 2), which, in general, flow from northwest to southeast. Except for the longest through-flow rivers and those of North Texas and the Trans-Pecos, most river systems are east or south of the Balcones Fault zone.
Amphibians reach maximum species diversity in East-central Texas, exceeded only in parts of the extreme southeastern United States. Amphibian diversity declines rapidly to the west.
Highest reptile species diversity for Texas and the United States occurs in Central Texas in the Austin area. Then, reptile diversity declines in all directions but is most pronounced to the northwest, in the panhandle region. Most turtles are dependent upon the availability of aquatic environments, whereas snakes and especially lizards seem to be more dependent upon the structural complexity of their environment.
The number of breeding bird species is highest in the western and southern regions of the state and declines eastward (matching continental trends). Mammal species diversity declines from west to east, most species being in the Trans-Pecos.
Although some species are widespread, having very broad ecological tolerances, there are 3 general patterns of vertebrate distribution in Texas.
- 1. East vs. West
- First, a major east-west discontinuity coincides with a north-south line from Fort Worth to Austin, San Antonio, and Corpus Christi. This faunal pattern corresponds to the abrupt elevational change along the Balcones Fault from Fort Worth to San Antonio. From there to the gulf, the line corresponds with soil (edaphic) differences. There are also climatic and floral correlations. West and south of the line the climate is xeric; to the east, mesic. Before Anglo-American settlement, the area to the east was tallgrass prairie and forest; to the west and south were plains (mixed and shortgrass prairies) and brushlands. Today, most of this area is cropland and grazingland.
- 2. North vs. South
- The second most prominent discontinuity occurs north and south of a line from Corpus Christi to San Antonio to Del Rio. As explained above, edaphic differences match the segment of the line from the gulf to west of San Antonio. From there to the Rio Grande, the boundary follows the Balcones Escarpment, which is a very rugged and abrupt topographic feature in this region.
- 3. Plains vs. Roughlands
- The third biogeographic pattern is another north-south interface occurring farther north. From east to west, the line connects Georgetown, San Saba, Brady, Eldorado, and Odessa. This boundary is less sharp than the others. It roughly corresponds to the irregular northern edge of the Edwards Plateau, the approximate southern limit of the Great Plains. To the south, the terrain is hilly, irregular, and more rocky. This is the region of the roughlands of the Edwards Plateau and Trans-Pecos, which are the eastern extension of the plateaus, deserts, and mountain ranges of the Southwest.
There are 4 regional trends in Texas biogeography. These occur at a lower distinction level than the 3 general trends but, nevertheless, are evident.
- 1. Eastern Forest vs. Oakwoods and Prairies
- This east-west segregation corresponds to a climatic gradient, primarily moisture, as well as edaphic (soil) factors that separate eastern pine-hardwood forests from western mixtures of oak woodlands and tallgrass prairies.
- 2. Edwards Plateau vs. Trans-Pecos
- These 2 roughlands are separated by an ecotonal area, the Stockton Plateau, which divides the hilly, more mesic Edwards Plateau to the east from the more xeric deserts and mountains of the Trans-Pecos to the west. Although the shift is not abrupt, the plateau is generally lower than the lowest basin elevation in the Trans-Pecos.
- 3. High Plains vs. Rolling Plains
- The north-south Caprock Escarpment of the panhandle forms an abrupt elevational separation of the high and low plains. The High Plains of the west are considerably higher and relatively flat and were uniform shortgrass prairie until converted to cropland and grazingland. The Rolling Plains to the east are more varied in topography and vegetation.
- 4. Coastal Zone vs. Inland Regions
- The influence of the marine environment as it interfaces with land along the Gulf Coast creates a unique, ever-changing, dynamic coastal zone that defines a narrow region that contrasts markedly with inland regions.
Based upon physiography and vegetation, Texas can be divided into 12 ecological regions (frontispiece). This biogeographic analysis of landscape ecology is very important, because this approach could improve the probability of long-term, effective land-use decisions in the best interest of economic and ecologic considerations. Unfortunately, we are far from achieving an integrated biogeographic approach. Most people not only are unaware of the landscape ecology in the area of their residence but do not know or understand how land-use decisions in other areas also affect them as well as the state as a whole.
1. East Texas Pine and Hardwood Forests
These timberlands are also known as the Pine Belt or "Piney Woods" because of the predominance of pine trees throughout much of the region. This area is part of the Southern Mixed Forest that extends westward into Texas from the Red River to within 25 miles of the Gulf Coast.
Physiognomy is medium to tall forest of broad-leaved deciduous and needle-leaved evergreen trees. Dominant vegetation is oak-hickory-pine-beech-sweetgum-magnolia. Plant community sites range from dry sandylands to permanent wetlands. There are 16 plant community types in this region, more than in any other region except the Trans-Pecos. Four community types are unique or rare (pine-oak woodlands, sphagnum shrub swamps, sandstone seeps) and 2 are threatened (American beech-southern magnolia, longleaf pine-tall grass). Three plants are endangered (white bladderpod, Texas trailing phlox, Navasota ladies'tresses). Several factors, especially the early effects of timber industries, complicate definition and subdivision of the region. However, there are 3 definite subregions, each recognized by the dominant species of pine, all of which are fire adapted.
The northern subregion is the largest and is characterized by shortleaf pine. Islands of this subregion occur in Red River and Leon Counties in the northwest and southwest, respectively. The central, eastern subregion is dominated by longleaf pine. It includes most of the "Upper" Big Thicket, i.e., that portion in which American beech is present. The southern subregion is characterized by loblolly pine. It includes a small portion of the "Upper" Big Thicket and the "Lower" Big Thicket, i.e., that portion in which American beech is absent. Islands of "lost" loblollies also occur westward in Bastrop, Fayette, and Caldwell Counties in the southern Post Oak Savannah.
The largest oil fields in the state are located in this region, and the value of the timber industry is second only to oil. This region also has the greatest variety of farming. Until 1945, farms were family or tenant operated and comparatively small, and livestock was commonly permitted to range freely in many localities. Since 1930, there has been a decline in the number of farms and a precipitous decrease of farms operated by tenants.
In former years, the practice of uncontrolled burning caused heavy losses of young timber and damage to wildlife habitats. Today, controlled burning is recognized as a useful tool in local rather than extensive management of both timber and wildlife.
Most timberland has been cut, and the sites are now producing the 4th generation of managed timber, primarily pines. Overcutting for saw and paper mills was once widespread in East Texas except on large private lands and on state and federal forests. Slash pine was introduced as a commercial species, and the most abundant grass, bermuda, also an introduced species, has become so thoroughly naturalized as to be popularly considered a native plant.
This region is also known as the land of "lakes," i.e., manmade reservoirs that inundate much of the original bottomland forest and associated wetlands that were large areas of fish and wildlife habitats.
Principal game species are eastern gray squirrel (bottomlands), eastern fox squirrel (uplands), white-tailed deer, and northern bobwhite. The eastern wild turkey was a valuable game bird during early days of settlement but was extirpated. Today, attempts are being made to reintroduce it into areas of suitable habitat. Black bears once inhabited this region but were exterminated by 1940. Importantfurbearers are Virginia opossum, raccoon, gray fox, and nutria (an introduced South American rodent). Minor furbearers are striped skunk and mink.
In response to the great variety of habitats within this region, there is a high diversity of nongame species. Examples of such habitat types are upland forests, forested bottomlands, pine stands, deciduous woods, mixed woods, rivers, swamps, bayous, sloughs, oxbow lakes, woodland edges, second-growth woods, open pine savannahs, sphagnum bogs, baygalls (shrub swamps), and seeps.
The only terrestrial species in Texas to become extinct since Anglo-American settlement inhabited the forests of this region (passenger pigeon, Carolina parakeet, and probably the ivory-billed woodpecker). Conservation management programs for some of the extirpated (4), unique or rare (2), threatened (15), and endangered (4) species are operational, but i, the red-cockaded woodpecker, is very complex and controversial.
There are many complicated wildlife problems. Formerly, much of the farmland was operated by tenants who were not active participants in conservation programs. There was widespread disrespect for protective wildlife laws strengthened by the time-honored system of the open range and large blocks of "company-owned" land.
Free-ranging (feral) pigs severely damage seedlings of longleaf pine crops and compete for acorns and other important mast. If uncontrolled, these animals can greatly compete with native wildlife.
Continued conversion of poor sandy soil from cultivation to pasture would be desirable if native wildlife cover and food plants were planted and/or not removed and grazing pressure were reduced.
East Texas forests and the trend to build large reservoirs for water resource development within major watersheds make the region especially well suited for recreation and industrial expansion. This provides habitat for many aquatic and semiaquatic species but eliminates extensive habitats of many bottomland forest species. Also, reservoirs change downstream flooding patterns, which adversely impact species composition and quality of floodplain forests. Furthermore, there are local conflicts between timber, hunting, and environmental interests.
2. Post Oak Savannah
This narrow oak belt is a forest, woodland, or savannah depending upon its location within the region. It is a narrow, highly irregular belt wedged between the East Texas Pine-Hardwood Forest to the east, Blackland Prairies to the west, and the Coastal Prairie and South Texas Brushlands to the south.
Physiognomy is medium to tall broad-leaved deciduous and some needle-leaved evergreen trees. The name of the region is derived from the predominant tree, the post oak. However, many other species of oak are common, as are hickories and other trees. There are 8 plant community types, of which 1 is unique (loblolly pine-post oak-blackjack oak). Two plants are endangered (large-fruited sand-verbena and Navasota ladies'-tresses). In the northern and eastern areas, timber is open and savannahlike, but in the southern and western areas, it is close and thickety. In the localities where marl (limy clay) outcrops occur, live oak is common. Farkleberry is a common understory plant in the northern area. Characteristic of the southern area is a thick understory of yaupon and eastern red cedar. Within about the last 40 years, a decided invasion of cedar has produced a noticeable scattering of this evergreen through the oaks.
Most of the plant species occur in other regions, but Post Oak Savannah soils are distinctive. The area is also known as the Clay Pan Savannah because a shallow, nearly impervious clay pan causes the soil to be unexpectedly arid. An exception is the Carrizo Sands area in Bastrop County, home of the unique "Lost Pines," a western range extension of loblolly pine. Sphagnum bogs also occur within this region.
The Post Oak Savannah is one of the first regions that was settled by Anglo-Americans because of its transition between forest and prairie. Cultivation severely eroded its soils, and grazing caused proliferation of understory thickets of yaupon and bumelia.
From 1830 to 1888, uplands were open and parklike with waisthigh grasses. Bottomlands were timbered and free of underbrush. Land not under rail fence was open range for cattle and hogs. Cultivation was primarily cotton, with smaller areas of garden crops.
By 1900, most land was fenced by barbed wire, and roads had been built. Much of the large timber had been used earlier for rail fences, fires were suppressed, and small trees and underbrush appeared.
From 1900 to 1930, undergrowth increased, and mast crops failed more regularly. From 1900 to 1944, cotton peaked and declined as the major crop, and crop diversification developed. Range was overstocked with livestock.
Since 1930, young oaks, hickories, and underbrush have dominated uplands. Loss of upland cover in cultivated areas resulted in long periods of flooding that killed large bottomland trees.
From 1950 to 1965, livestock production increased. Large tracts of hardwoods were cleared and converted to improved pastures. Since 1965, this trend has continued, and farm production has declined.
Prior to 1860, game in the Post Oak Savannah was apparently plentiful. Principal species were white-tailed deer, wild turkey, northern bobwhite, and eastern fox and eastern gray squirrels. At that time, as well as today, the Rio Grande wild turkey inhabited southern areas. The eastern wild turkey was originally native to northern areas, and attempts are being made to reintroduce it into suitable habitat. In winter, ducks were present, and passenger pigeons once roosted locally in large numbers.
Between 1860 and 1920, wildlife began a rapid decline with the increase of settlers. Year-round hunting with no bag limits was a common practice. Passenger pigeons were extinct by 1900, and turkeys and deer were killed in such numbers that by 1920 so few were left that hunting was unproductive. Quail and squirrels were exceptions to this trend. They were abundant and maintained their numbers during this period.
Between 1920 and 1948, quail, squirrels, and ducks were principal game. Farming practices provided optimum quail habitat, and populations thrived. Squirrels were abundant in timbered bottoms, and thousands of ducks wintered in the bottomlands.
From 1948 to the present, quail populations declined with changing land use from cropland farming to improved pastures, and this trend continues. Squirrel and waterfowl populations have maintained themselves in suitable habitat and provide abundant hunting opportunities. The deer population has continued to increase, and deer hunting provides the major recreation in this area.
Major furbearers of this region are raccoon, Virginia opossum, coyote, and striped skunk. Minor furbearers are nutria, gray fox, and American beaver. Depleted species include 1 extinct, 3 extirpated, 2 unique or rare, 7 threatened, and 3 endangered. Perhaps the best known of these is the endangered Houston toad, which is found in the Lost Pines area of Bastrop County.
Free-ranging hogs severely damage wildlife habitat and compete for food; however, "hog hunting" has recently become quite popular with many sportsmen.
Wildlife will continue to be influenced by land-use practices and can only exist as long as suitable habitat is provided. The current trend toward conversion of hardwood timber and brushland to improved pastures effectively removes this acreage from wildlife production and results in depletion of this resource. Also, as in the East Texas forest region, the trend to build large reservoirs eliminates bottomland habitats of many species.
To meet future energy demands, large areas of the Post Oak Savannah are being strip-mined for lignite. This could result in destruction or permanent alteration of productive aquatic and terrestrial habitats for wildlife unless proper protective measures are undertaken to reclaim and revegetate these areas with native plants.
3. Blackland Prairies
The major Blackland Prairie extends in a southwestern direction as a broad wedge-shaped area from near the Red River in Northeast Texas to the vicinity of San Antonio (Bexar County), where it merges with the brushlands of the Rio Grande Plains. The eastern boundary is the Post Oak Savannah; the western boundary is the Edwards Plateau except in the north, where it is separated from the Grand Prairie by a narrow strip of forest—the East Cross Timbers. Minor prairies (Fayette, San Antonio, Vegua, and Washington) lie somewhat parallel and south of the major prairie.
Original physiognomy was medium-tall, rather dense grasslands with scattered open groves of deciduous trees in minor prairies. Dominant grasses were dropseeds, switchgrass, eastern gamagrass, yellow indiangrass, and big and little bluestem. There were osage orange, sugar hackberry, eastern red cedar, oaks, elms, pecan, and eastern cottonwood in scattered mottes, knolls, hills, escarps, ridges, and bottomlands. Today, in addition, honey mesquite is common throughout the prairies.
There are few unique or rare species. However, the original 7 plant community types themselves are almost gone. Only a few small, scattered parcels of a total of 5,000 acres (0.04%) of the original 1 2 million acres remain. The 3 basic community types are threatened with extinction (gamagrass-switchgrass, little bluestem-indiangrass, and silveanus dropseed). The rich, unique blackland soils were derived from the activities of abundant soil organisms at least as diverse as those above ground.
The moldboard plow, perfected by Thomas Jefferson about 1800, gave settlers an implement that could turn heavy, fertile clay soils. In time, equipment improved, and heavy draft mules were brought into the region. Corn was grown to feed the mules and horses that supplied power for agriculture. The economy that motivated development of the Blacklands was "white gold"—cotton. Railroads and heavy farm equipment (steam tractors) put the area in the cotton-producing business. Peak productivity was reached in the mid-192o's but then declined due to loss of soil fertility. In the 193o's, along with general concern for soil loss, practices were developed to curb erosion and to return soil fertility.
Today, most of the Blackland Prairies are under cultivation or are being grazed. Unfortunately, much of the early soil depletion damage cannot be restored. As a result, short grasses and brush have replaced most of the originally dominant tall bunch grasses. However, a few native hay meadows have been preserved and constitute accurate representations of the composition of the original prairie vegetation. This region is the most thickly populated area in the state and contains along its western border more of the state's large and middle-sized cities than any other area.
Originally, the Blackland Prairies had large numbers of American bison, pronghorn, plains gray wolf, red wolf, and greater prairiechicken. These grassland species are now gone, being incompatible with intensive agriculture. Under modern conditions, the Blackland Prairies have low game production. The wooded belts along streams once had numerous white-tailed deer and wild turkeys and still provide much of the border type of environment necessary to many species of
The mourning dove is the most important game species in this region. Northern bobwhite populations are found in "grass" years when sufficient food and cover result from plentiful rain. Eastern cottontails are a source of sport and food. Eastern fox squirrels and bullfrogs are important in areas where suitable habitat remains. Major furbearers are raccoon, Virginia opossum, and striped skunk. Minor furbearers are ringtail and eastern spotted skunk. In addition to 4 extirpated species, 6 are threatened, but none are endangered.
Floodwater-retarding structures provide satisfactory habitat for game fishes and waterfowl. With proper preproject planning and accommodations for management, excellent habitats could be provided by these water impoundments, and the impact could be significant. In recent years, the furbearer resource has been important and is an incentive for preservation of their habitats, especially bottomlands. Successful wildlife management in the Blackland Prairies depends upon intentional application of farming and grazing practices and watershed conservation to provide habitat.
4. Gulf Coast Prairies and Marshes
4a and 4b. Dune/Barrier Islands and Marshes
The Dune/Barrier Islands and Marshes include a 3-20-mile-wide arc of coastal flats having smooth terrain with low relief. There are alluvial embayments, fluvial and deltaic deposits, sand beaches, barrier islands, and mud flats. Artificially created dredge spoil islands are also included in this region.
Physiognomy is open, short to medium-tall grassland with occasional shrubs and medium to very tall grassland, often very dense. There are 6 plant community types. None are classified as unique, rare, threatened, or endangered. Dominant coastal vegetation is sea-oats and seacoast bluestem. Farther inland, smooth cordgrass dominates. Other components are dwarf saltwort, sedges, crotons, coastal saltgrass, Pan American balsamscale, morning-glories, rushes, wolfberries, Jamaica sawgrass, panicums, paspalums, common reed, arrowheads, bulrushes, sea purslanes, cattails, pricklyashes, and marshmillet. The floral composition is rich—about 45% of vascular species native to Texas are found within this region. The crown shape of trees, especially oaks, is greatly affected by the almost continuous salt spray and is quite noticeable around High Island and on the Aransas National Wildlife Refuge.
Although plants are abundant in this region, beneficial aquatic species and open water areas necessary for wildlife are being threatened by several introduced pest weeds, foremost of which are water hyacinth and alligator weed. Some native plants are also increasing, e.g., cattails, waterlettuce, common frogbit, American featherfoil, and waterprimroses. Habitats especially threatened are streams, canals, lakes, and ponds.
These marshes and barrier islands contain several popular state parks and wildlife management areas and national parks and wildlife refuges. Urban, industrial, and recreational developments have increased in recent years. Most land is not well suited for cultivation because of periodic flooding and saline soils. However, much of the area is grazed, resulting in overgrazing on coastal islands.
Principal game species are ducks and geese. Two thirds of the waterfowl population of the Central Flyway winter in this area and the adjacent Coastal Prairie. This includes 12 species with 90% of their winter population within these regions. During the hunting season, sportsmen from many parts of the United States come to the Texas Coast for unexcelled waterfowl shooting. Minor game birds are rails, gallinules, and coots. Important furbearers are raccoon, Virginia opossum, nutria, and muskrat.
A large number of fish and wildlife species is dependent upon this long, narrow coastal zone; some are resident, some transitory, and many aquatic species spend critical parts of their life cycles in this area. The marshes are spawning and nursery areas for fin- and shellfish. Tidal flats are important feeding grounds for many species of coastal birds. Manmade islands, created by the dumping of dredged spoil materials along the Intracoastal Waterway, are used by many species of birds for nesting. These spoil banks, when protected, are sanctuaries for a number of coastal species that have been driven from their native nesting habitats by human activities.
The West Indian manatee is extirpated from the Texas Coast. Two species are unique or rare. Twenty-three species are threatened, and 9 endangered species are dependent upon this region, the best known being green, Atlantic hawksbill, leatherback, loggerhead, and Atlantic ridley sea turtles; brown pelican; reddish egret; Arctic peregrine falcon; whooping crane; piping plover; and Eskimo curlew. Attwater's greater prairie-chicken formerly inhabited barrier islands on the upper and central coast.
The 2 most critical habitat types are wetlands and submerged grassflats. The highly productive wetlands are essential to many species, marine and terrestrial. Habitat quality has been diminished by reduced freshwater inflows due to marsh draining and filling, flood control measures, channelization, dredging, and other developments. Wildlife losses that result are often so subtle they may not be noticed until considerable change has occurred. Many species are declining in abundance, especially those dependent upon wetlands.
In 1923, only 600,000 people lived on the Texas Coast. Today, the population is about 4.5 million, or 26% of the state total. This impact has caused serious problems involving wildlife, but it has been estimated that 85% of the coast can be maintained in a healthy state by carefully planned management. Such management can provide high quality economic and aesthetic opportunities and can maintain varied vital habitat, all of benefit to mankind and wildlife.
4c. Coastal Prairie
The Coastal Prairie is an almost level strip 20-80 miles inland from the zone of dunes, barrier islands, and marshes. There are 2 subregions separated near the vicinity of the San Antonio River: the wider northeastern section is nearly flat grassland prairie, and the subhumid, more narrow southern section of similar relief consists of coastal brush.
Physiognomy is medium to tall, dense to open grassland. There are 12 plant community types, of which 1 is threatened and 2 are endangered. Three plants are endangered. Dominant vegetation is seacoast bluestem and Gulf cordgrass. Other components are bluestems, threeawns, buffalograss, sedges, panicums, paspalums, indiangrasses, dropseeds, needlegrasses, and rattlebush. Within the Coastal Prairie are 575,000 acres of forests extending from Galveston County westward to the drainage of the Lavaca River in Jackson and Calhoun Counties. Principal trees are oaks, pecan, ashes, hackberries, eastern cottonwood, American sycamore, willows, and some loblolly pine. Except along the Trinity and San Jacinto Rivers, bottomland forests do not reach the coast. Deltaic deposits and banks of the lowermost stretches of other rivers are occupied by salt meadows and marshes.
Since the early days of Anglo-American settlement, much of the southern and inland area as far north as the Brazos River has been greatly modified by agriculture. Before the period of cultivation, intensive grazing reduced the grass cover to the extent that mesquites, live oaks, pricklypears, and acacias became established and dominant. In some areas, recent brush control programs have been so effective that scarcely a trace of original prairie or secondary brushland remains. Few open prairies remain; most have been transformed into farms and ranches or absorbed into urban areas. Much of the area has been continuously grazed and invaded by exotics such as Macartney rose and Chinese tallow tree as well as native mesquite and huisache.
Waterfowl are principal game species in rice fields and marshes. Timbered bottomlands afford good habitat for white-tailed deer and eastern gray and fox squirrels. Prairies contain suitable habitat for mourning doves and, locally, northern bobwhites and sandhill cranes. Major furbearers are raccoon, Virginia opossum, and nutria. Ring-necked pheasants have been established as game birds in some counties of the Upper Coastal Prairie.
Four species are extirpated from the Coastal Prairie, and there are 18 threatened and 4 endangered ones. The precariously endangered Attwater's greater prairie-chicken is still present in small numbers in a few localities and is being carefully managed on the Attwater Prairie Chicken National Wildlife Refuge established for its preservation. Its existence is threatened by habitat loss.
Reduction and deterioration of wildlife habitats have been caused by tree and brush clearing, intensive agriculture, urban development, and land fragmentation. Much of the area, once protected on large ranches, is now subjected to uncontrolled development. This has resulted from the fragmentation of ranches due to increased land taxation.
5. East and West Cross Timbers and Grand and North Central Prairies
This is a complex transitional area of prairie dissected by 2 parallel timbered strips extending from north to south. The region is located in North-central Texas west of the Blackland Prairies, east of the Rolling Plains, and north of the Edwards Plateau and Llano Uplift. The origin of the name "Cross Timbers" is obscure, but it may refer to the crossing through timbered areas from adjacent grasslands when the first Anglo-Americans traveled there. It may also refer to the longitudinal axes of the timbered tracts, which are crosswise to the rivers and creeks (pers. commun., Charles D. Tipton).
There are 4 plant community types, none unique, rare, threatened, or endangered. However, a rare plant, the Comanche Peak prairie clover, grows among limestone outcrops. Physiognomy is oak wood and tallgrass prairie. Dominant plants are post and blackjack oak, hickories, and tall and midgrasses, e.g., big and little bluestem, yellow indiangrass, and sideoats grama.
Range and pasture utilize over half the West Cross Timbers, and the remaining land is used for farming. All these uses are increasing. Major land uses and future intensification in the East Cross Timbers are range, pasture, urban development, and farming. Much of the native vegetation of the region has been plowed and grazed intensively. In areas of the North Central Prairie heavily used by livestock and where prairie fires have been suppressed, native grasslands have been replaced by honey mesquite, lotebush, and grasses more tolerant of grazing, e.g., silver bluestem, Texas wintergrass, and buffalograss.
The white-tailed deer is the only big game animal of significance in this region. Upland game animals are the Rio Grande wild turkey, northern bobwhite, and eastern fox squirrel. Migratory game birds include the mourning dove and wintering waterfowl. Important furbearers are raccoon, Virginia opossum, coyote, striped skunk, ringtail, gray fox, and red fox (introduced European species). Two species are extirpated, 1 is unique/rare, 7 are threatened, but none are endangered. Major land-use trends affecting wildlife are intensive grazing, brush removal, and development of improved pastures, rural areas, and water impoundments.