A Century of Land Use in Texas: Impacts on Wildlife Diversity
Texas is a legendary place, not only because of its great size and its unusual history, but also because of its richly varied landscape, which has always inspired in its residents a strong sense of place and a powerful love of the land. From the Pineywoods of East Texas to the mountains and deserts of the west, from the Great Plains in the north to the subtropical Rio Grande Valley, from the springs and rivers of the Hill Country flowing to the bays and estuaries of the Gulf of Mexico, few places can equal Texas’s scope and diversity. It has also supported a diversity of people and cultures over the centuries, and this diversity has been increasing as the population of the state has exploded in the past decades.
As we begin the 21st century, it is obvious that great changes have come to the Texas landscape, some so slowly that the differences have been difficult to see, some so quickly that residents can’t help but notice. A century ago, Texas was a sparsely settled rural stronghold whose three million people lived and worked mostly on farms and ranches. With an average distribution of 11 people per square mile, there seemed little prospect at the time of running out of natural resources or places to experience the outdoors. Now, however, the state’s mostly urban population, which exceeds 20 million, is distributed unevenly across the state, putting increasing pressure on the environment within and around its rapidly expanding urban areas. People have to drive farther and farther to experience the natural world that was once within easy reach.
The lay of the land in Texas is distinctive in yet another way. For all of its deeply etched images of wide-open spaces, Texas is unusual in its relative lack of public lands. During its brief time as a republic, Texas sold the bulk of its public lands in order to finance a government. As a result, despite its size, the state owns relatively few public spaces in proportion to its population. More than 94 percent of the state’s land remains in private hands. The relative lack of public lands is also a crucial factor in outdoor recreation. For the 99 percent of the population in Texas that does not own a stretch of land, such as a farm or ranch or weekend getaway, the opportunities to enjoy the outdoors have depended, in large part, on access to parks. However, areas of parkland, wildlife refuges, and forests make up less than 3 percent of the state.
These geographic and demographic factors that make Texas such a distinctive place have also made the work of conservation and of providing outdoor recreation opportunities for all Texans an increasingly complex and difficult task.
The Biological Survey of Texas
Texas is fortunate that the U.S. Congress funded extensive biological surveys of the state at the end of the 19th century and the beginning of the 20th century. These surveys were conducted as part of the program directed by the U.S. Bureau of the Biological Survey, which was established in 1885 as a division of the U.S. Department of Agriculture. The purpose of the surveys, which were directed by the legendary conservationist C. Hart Merriam, was to inventory wildlife and assess its practical value.
Merriam selected a series of states, including Texas, for an intensive biological survey and inventory. Over a period of about 20 years (1889\-1906), a team of 12 scientists and field agents led by Vernon Bailey extensively surveyed the state. In Texas the federal field agents compiled an equivalent of more than 5 years of continuous fieldwork. They prepared written reports describing the state’s physiography and plants and listing the birds and mammals they observed or captured at 178 different sites in every ecological region of the state. Many of these sites have changed dramatically today.
The culmination of the survey was the 1905 publication Biological Survey of Texas, which was authored by Bailey and included information about life zones, reptiles, and mammals. Henry Oberholser, a colleague of Bailey’s and one of the federal agents on the survey, made his study of the bird life of Texas a life-long project, and his report did not appear until 1974.
The recent discovery of the original files from this historical biological survey gives a virtual natural history picture of every region of the state as it existed a century ago. In 1992 I initiated a project to document the archival natural history information from the Texas biological survey. The archival materials assembled included scientific specimens of birds, mammals, and reptiles; museum catalogs of the scientific specimens; field-trip diaries describing the travels of the field agents; detailed biological reports of significant topics; physiographic reports of each place visited in Texas; special correspondence with landowners and field agents; a detailed map of the life zones of Texas; and more than 1,000 black and white photographs of Texas landscapes, habitats, plants, and animals. In addition, several maps of plant and animal distributions prepared by the federal agents were located. These archival materials represent a detailed depiction of Texas natural history at the turn of the century. This information provides crucial baseline data to compare with the results of current biological surveys and to assess landscape and biotic change information useful to land managers and others seeking to improve land and ecosystem management. My most recent book, entitled Texas Natural History: A Century of Change, includes an annotated version of the original Biological Survey of Texas as well as several chapters describing what Texas was like more than 100 years ago and what happened to the state during the 20th century.
Changes in Texas Ecosystems and Wildlife Diversity
Mammals illustrate some of the patterns of ecosystem and faunal change that took place in Texas during the 20th century. Mammals were the major group of vertebrates featured in the historical biological survey, and the recent publication of The Mammals of Texas (Davis and Schmidly, 1994), which summarizes the current status of mammals, provides a context for understanding change in this highly visible component of the fauna. For mammals, the most significant changes include the extinction of populations, subspecies, and species; introductions of nonindigenous species; and major changes in species or subspecies distributions.
Species extinctions have been common. By 1905 the only species of mammals extirpated from Texas were bison, grizzly bear, and elk, although several other species, such as beaver, black bear, spotted cats (ocelot and jaguar), pronghorn, and bighorn sheep, were markedly reduced in distribution or in numbers. Today, the gray wolf and red wolf, black-footed ferret, jaguar, margay, and bighorn sheep are extirpated from the state.
Since the turn of the 20th century, however, a few species have expanded their ranges—the armadillo and the pygmy mouse are notable examples among mammals—whereas others, such as the pronghorn antelope, have undergone drastic range reductions. Entire populations of some subspecies, such as the Big Thicket hog-nosed skunk, have become extinct.
A striking example of the changes occurring in Texas is the plight of the black-tailed prairie dog. This highly social creature was so numerous during the time that Bailey and the field agents worked in the state that a 25,000-square-mile area of plains east of San Angelo was described as a continuous dog town, inhabited by as many as 400 million animals. Following an extended program of extermination, the population was reduced to small, scattered colonies. Today, it is estimated that 98 percent of the population has been lost and that only 300,000 prairie dogs remain in Texas—an estimate that some scientists feel is actually too high because of the small size of the colonies and their scattered nature.
Nonindigenous species, which were rarely encountered by Bailey, now openly range over much of the state. A prime example is the nutria, which was introduced into the state in the 1930s and now occurs over most of the eastern two-thirds of the state and is still expanding its range. Ungulates introduced from Africa and Asia now occupy rangelands in proliferating numbers. During the 1990s a colony of feral Japanese snow monkeys even became established in South Texas.
Anthropogenic pressures on wild species today are totally different from those earlier in the century. In the early 1900s overexploitation resulting from unregulated market hunting was a serious threat to wildlife. Poisoning, trapping, and unrestricted killing decimated many species. Today the hunting of game species is an important management tool regulated by state law, and the revenue from hunting has become an effective market incentive for landowners to manage for wildlife habitat. Likewise, there are laws to prevent unregulated taking of endangered or threatened species.
Today more problems are related to wildlife habitats that have been destroyed, altered, and fragmented. Loss of critical habitat is the most serious threat to the modern fauna. Early Texas was a magnificent place, with a tremendous diversity of habitats. At one time the state was mostly composed of grassland habitat—the southern reaches of the Great Plains—but human population growth and settlement through the past two centuries have significantly affected Texas. Among the most altered places are the prairies and wetlands, the riparian and riverine ecosystems, and the rangelands of the Edwards Plateau, Rolling Plains, South Texas Plains, and Texas Panhandle. When Texas entered the Union, it was the largest prairie state, but today fewer than 2,025 hectares of the original 5 million hectares of blackland prairies remain. Texas has lost more than 60 percent of its wetlands and about the same percentage of its bottomland hardwood forests.
It becomes evident when assessing the old photographs from the archive that the amount of natural, unpolluted surface water has declined greatly this century. Almost every photograph the agents took of a stream or river showed abundant natural surface water, which is not true of most of those places today, although the total amount of surface water in the state is probably greater today because of the construction of tens of thousands of tanks and large reservoirs.
A little-appreciated but important factor affecting natural ecosystems in Texas today is the rapid change in land-tenure systems. Unfortunately, an unprecedented breakup of family lands is now occurring in many places, brought about by changing economic conditions, inheritance taxes, and a state financial structure that is extremely dependent on property taxes. For example, throughout much of Central Texas, where only tiny remnants of the native landscape survive today, the average tract size in many counties has dropped in this generation alone from thousands of hectares to fewer than one hundred. These areas, which once provided large blocks of land for wildlife habitat and outdoor recreation, now consist of tiny plots of introduced vegetation that cannot sustain the native wildlife.
20th-Century Changes in Texas Landscapes and Land Uses
Human disturbance in Texas prior to European colonization was minimal, but the rapid spread of people across the state throughout the 19th and 20th centuries greatly accelerated landscape changes. Population growth presents a formidable challenge to conservation because fish and wildlife resources and people share near identical needs for two critical commodities: water and land. The following discussion summarizes some of the major factors resulting from population growth that have changed the face of Texas landscapes.
Land conversion and development.
During the 20th century, land cover in Texas was altered principally by human activity, such as farming and agriculture, ranching and stock raising, logging, the suppression of natural fires, and construction associated with expanding urbanization. Urban development, including both urban sprawl and development of vacation homes, has had a huge impact on the landscape of Texas. Most of this growth occurred around major cities where 80 percent of Texans now live. Natural habitats are often reduced by land conversion, leaving less area available for native species. The spatial patterns of habitat may also be altered, resulting in the fragmentation of once-continuous habitat. With urbanization and population expansion came the need for dams, water diversions, and roads to support people’s needs and facilitate their movements. Most changes in aquatic systems in Texas can be traced to the construction of dams, either for water storage or flood control, and to other developments on or near waterways. Dam building and water diversions have significantly degraded most major rivers and coastal waterways.
Misuse of water.
Of all the water resources in Texas, rivers are by far the most seriously threatened. Rivers link our land and water ecosystems. Adequate stream flows and good water quality are essential to their health and the ecosystems they pass through. Every major river basin in Texas has been impounded, and nearly 6,000 small dams create a network of small reservoirs for livestock watering and soil stabilization. These impoundments have substantially altered our hardwood bottomland and riverine/streamside landscapes.
Suppression of fire.
When Texas entered the Union, it was the largest prairie state, and fire was a major factor in shaping the landscape and land cover. This is no longer true today. Beginning in the 19th century and continuing throughout the next, fire suppression has had a huge impact on the natural conditions throughout the state. The cessation of frequent natural surface fires in the late 1800s was because of reduced vegetation caused by intensive grazing by livestock. The initial suppression of natural surface fires by livestock grazing led to a period of active suppression of all fires by land management agency personnel shortly after the beginning of the 20th century. Before fire suppression, Texas ecosystems were accustomed to frequent, low-severity wildfires that facilitated landscape and habitat diversity. Under conditions of fire suppression, landscape complexity is made simpler with shade-tolerant tree and shrub populations rapidly expanding. Without question, fire suppression over the past century has pervasively affected many Texas ecosystems.
Invasion of alien plants.
By the end of the 19th century, alien plants had already successfully invaded Texas landscapes. By the end of the 20th century, alien plants would be common all over the state. In particular, the salt cedar, or tamarix, has inflicted damage to our native landscapes and habitats. It is a vigorous invader of moist pastures, rangelands, and riparian habitats, having spread to almost every river, stream, creek, and wash in the southwestern part of the state. Salt cedar has an extremely high rate of evapotranspiration, and annual water losses often result in a substantial decline in water tables where it is abundant.
A similar situation exists along the upper Texas coast where the Chinese tallow tree from Asia proliferated substantially during the 20th century. The invasion of this plant into coastal Texas has changed much of the region from coastal prairie to monotypic tallow woodlands, displacing native plant and wildlife species.
Loss of wetlands.
Land conversion and land use throughout Texas has had a strong impact on wetlands, hardwood bottomlands, and riparian areas. Although wetlands comprise less than 5 percent of the state’s total area, Texas has lost an estimated 50 percent of its coastal wetlands and 60 percent of its terrestrial wetlands in the past two hundred years. This trend continues today as much of the remaining acreage is being seriously degraded by saltwater intrusion because of the construction of canals, channels, and drainage ditches; by land subsidence and groundwater depletion; by inadequate freshwater inflows because of upstream water projects (dams) and the alteration of natural hydrology; and by pollution from industry, shipping, and urbanization. Large-scale loss and degradation of riparian landscapes throughout the state have resulted from the construction of impoundments; overgrazing by livestock, which has destabilized vegetation and resulted in arroyo cutting and gullying of the landscape; and the introduction of alien plants such as salt cedar and Russian olive.
Encroachment of brush.
Since the turn of the 20th century, brush and cacti have continued to cover many areas of the state that were formerly prairie or grassland. The spread of species such as mesquite, cedar, scrub oak, and prickly pear can be attributed primarily to overgrazing and the suppression of wildfires that so often swept over the western plains in the past. The two most obvious culprits contributing to the increase in woody plants have been mesquite and juniper.
Grazing of livestock.
Widespread grazing of domestic livestock has had major cumulative effects on the ecology of Texas. The extremely high historical stocking rates and concomitant overgrazing led to significant alterations in the species composition of vegetation across the state. Cool-season grasses and other preferred forage species declined, while unpalatable weedy species, shrubs, and nonindigenous plants increased. The year-round, high-intensity grazing of open ranges that occurred in the past also led to marked reductions in herbaceous plant and litter cover. Overgrazing was also a major contributor to soil erosion, flooding, and arroyo cutting. Livestock grazing, together with fire suppression, both interacting with fluctuations in climate cycles, has had a major impact on land cover in Texas. Range deterioration continued through the drought of the Dust Bowl era in the 1930s but has improved since. Although there are still many areas of the state in need of brush management and removal, the current status of our rangelands does indicate that range can be improved with good management and favorable climatic conditions.
Fragmentation of land.
Habitat fragmentation is rapidly becoming the most serious threat to landscape integrity in Texas today. Habitat fragmentation is a process by which stands of native vegetation become smaller and discontinuous because of the clearing of land for various purposes, such as agricultural, residential, or commercial use. The effects of habitat fragmentation on animals, plants, and their habitats are numerous, and the biological diversity of native species is almost always reduced. As cities spread and urban dwellers seek land ownership outside the confines of city limits, land holdings exhibit accelerating fragmentation and those species that rely on large continuous tracts begin to decline.
Texas is not alone in its struggle to manage its resources while at the same time meeting the needs of its rapidly expanding populations. As we look to the future, there are at least 10 challenges essential to effective conservation of natural resources, open space, and wildlife diversity. These are briefly discussed below.
Find a common ground for managing wildlife diversity.
Strong positions have been staked out on the extremes of the spectrum of approaches to conservation, and it has become difficult to find a common ground where the majority of people can seek compromise for the common good. Advocacy groups have taken over and polarized the debate because no one has offered society an acceptable alternative to the winner-take-all strategies. Wildlife professionals, who have devoted their careers to the management and conservation of wildlife resources, must take the lead in creating this common ground.
Set priorities based on current data: the case for monitoring.
If we are to conserve wildlife diversity in Texas, we must have an adequate foundation of knowledge on which to base management decisions. Clearly, what is needed to retard the events that could transpire in this new century is information on the status of vertebrate species as well as monitoring systems to indicate when a species appears to be in some danger.
Recognize the changing nature of our clientele.
We must recognize that our clientele is no longer made up of just hunters. Certainly, we must work to increase the understanding of hunting as a viable method of wildlife conservation, but we must broaden our approach to include opportunities for the nonconsumptive enjoyment of wildlife. One area that holds much promise is wildlife-related tourism, or nature tourism, which increased worldwide by 63 percent from 1980 to 1990 and is now the fastest-growing sector in the travel industry.
Avoid single-species approaches.
Environmental monitoring and single-species approaches can help divert problems before species become extinct, but this is a labor-intensive and extremely expensive solution. The least expensive solution is to manage at the ecosystem level, thereby attempting to conserve through time an entire assemblage of species. In a state like Texas, with its enormous biological diversity, this is really the only long-term approach that is feasible. We do not have the financial or human resources or the time to take a single-species approach toward managing our wildlife resources. We must develop a broader management approach that will consider ecosystems and landscapes and all biological resources instead of a limited subset of species and their habitats.
Focus on sustainable resource systems and ecosystem management.
To succeed, resource management must be considered in the context of an ecosystem, where resource development, conservation, and protection are considered simultaneously. Competition for resources must give way to cooperative management strategies, where conservation and resource management are linked in sustainable resource systems. Such an approach affords the opportunity to focus on processes through which ecological and human communities are linked, such as the flow of water through a regional watershed, the nutrient cycles that help sustain productive soils, and the seasonal patterns of reproduction and regeneration that characterize the ecological community. We must go beyond resources and yields to include the full range of services, values, uses, diversity, and continuity of ecological services.
Strengthen scientific research capabilities.
More effort is needed to develop the basic knowledge and tools that are the scientific foundation for managing wildlife. Wildlife research must improve in quality and at the same time broaden its scope if societal issues are to be adequately addressed. Essentially all the major scientific challenges will require changes in the way researchers organize themselves as well as improvements in technology. It will be necessary to enhance and promote interdisciplinary research to promote new technology and different research approaches. As wildlife issues become more complex, the need for interdisciplinary research will become even greater.
Make conservation education a priority for the public.
People must be educated to understand what the continuation—or destruction—of wildlife means to their future and that of their descendents, and they must be persuaded to act on their resulting concerns in ways respectful of the diversity of life and their own cultural values. We must also reach beyond traditional commodity-oriented values to address the entire spectrum of values that society places on wildlife resources. Unless we broaden our clientele base, the public confidence to gain the political power and resources to conserve wildlife diversity will not be forthcoming. One of the most critical educational challenges in Texas will involve engaging minorities in conservation issues.
Increase participation of private landowners.
With 94 percent of Texas lands in private hands, most of the state’s native plants and animals reside on private land. What’s more, the locations that are most desirable for homes and developments, such as areas around springs and streams and on hills overlooking unspoiled vistas, are often the areas where habitat is most fragile and most critical. As a result, developers and conservation interests often conflict. As a matter of sheer practicality, the concerns of private landowners, the traditional stewards of the land, must be considered when addressing the growing problems of conservation in Texas. Therefore, we must find ways to encourage and not discourage the participation of private landowners in wildlife management. There is a real opportunity to create incentive programs that provide technical or cost-share assistance to private landowners for voluntarily enrolling environmentally sensitive land or wildlife habitat in conservation programs to protect or enhance natural resources.
Expand acquisition and management of protected areas.
Although they represent only a small part of the Texas landscape, parks and preserves and the federal, state, and private entities that oversee them play increasingly vital roles in the conservation of biodiversity in Texas. For some regions, such as the Rio Grande Valley, they represent what is left of the native habitats. Clearly, there is a need for more parks and preserves and additions to existing areas to protect rare or unique natural resources and to better represent the natural regions of the state. Given their concerns about conservation and scenic beauty, Bailey and the federal agents who produced the biological survey, if they were alive today, would surely endorse such a strategy for the 21st century.
Promote regional conservation planning.
There is a growing consensus that conservation is best practiced at the regional level where it can be integrated with local customs, values, and land uses and where people can have a vested interest in and become direct participants in the decision-making process. In the future, we must begin to effectively plan for various land uses within the dynamics of landscapes.
There are many excellent examples of how each of these 10 strategies are being implemented in Texas today by various stakeholders, including state and federal agencies, private conservation organizations, public groups, and private landowner organizations. In the future, we must encourage more interaction among the various stakeholders to continue these collaborative efforts.
The Special Challenges of Land Fragmentation and Water
Land fragmentation and the misuse of water had become the dominant conservation issues by the end of the 20th century, and they will continue to be the most significant challenges in the 21st century. Texas is no longer a state in which economy and culture are defined primarily by the land. With the continuing influx of new residents and a population increasingly shifting to cities and their suburbs, Texas has become a primarily urban society. Many landowners whose families have lived on the land for generations have come under tremendous pressure to sell their farms and ranches for development. As a result, Texas is in jeopardy of losing its legacy of families who live and work on the land—the traditional stewards of our natural heritage.
The fragmentation of large family-owned farms and ranches poses perhaps the greatest single threat to our wildlife because it places once-plentiful habitat for native plants and animals increasingly at risk. For this reason, it is crucial to find ways to keep large contiguous tracts of land intact and to find ways for all landowners to participate in conservation. This will require us to create incentives such as programs for the purchase of development rights. This program would allow landowners to sell the development rights to their land by granting conservation easements to a government entity or nongovernmental conservation organization, yet retain all other rights of ownership, including the right to continue ranching, farming, hunting, and fishing.
Management of water will be the single most critical conservation issue in Texas in the 21st century. Water is the limiting factor for all aquatic life, plants, and wildlife. Rivers link our land and water ecosystems. With Texas’s population expected to double in the first three decades of this century, there is an urgent need to maintain sufficient water for adequate flows to rivers, lakes, and estuaries to maintain the fish and other wildlife species that depend on them. Historically, the allocation of water rights in Texas has not taken into account the needs of the state’s ecosystems. Our current water statutes and regulations require that environmental needs be considered in the overall picture, but they do not assure minimal instream flows to sustain the health of rivers and estuaries. As Texas attempts to meet its increased water needs, it must not impair the ecological health of these ecosystems.
Some Possible Solutions
In response to the need for quick action, two recent studies were commissioned to develop recommendations for strengthening conservation efforts and improving access to open space and the outdoors for Texans. While serving as governor, George W. Bush appointed a task force on conservation. The report of the task force, entitled Taking Care of Texas, was issued in October 2000 and contained recommendations in three broad categories: private lands (incentives, partnerships, and stewardship); public lands (planning, repairing, developing, and meeting future needs); and water (assuring, protecting, and managing for conservation). Regarding private lands, the cornerstone recommendation of the task force was the implementation of program for the purchase of development rights whereby government agencies or nonprofit groups acquire development rights from farmers, ranchers, and other owners of open space. Although the land remains in private hands and is closed to the public, it can never be converted into shopping centers or housing. Recognizing that Texas possesses a very small amount of public land and the need for access to the outdoors is acute, the Bush task force also concluded that land acquisition must be “an important component of any statewide plan.”
In a parallel and complementary effort, the Texas Parks and Wildlife Department contracted with Texas Tech University to conduct a study, which resulted in a report entitled Texas Parks and Wildlife for the 21st Century. The report, issued in November 2001, recommends adding 1.4 million acres of state parkland and 559,000 acres of local parkland over the next 30 years. It also calls for preserving a total of 1.1 million acres of native habitat in the state’s 11 ecological regions, although it concluded that some of the habitat could serve as parkland and some could remain in private ownership. The study found an acute shortage of outdoor recreation lands near cities. Based on a survey of public opinion, the Texas Tech study revealed Texans’ overwhelming support (in excess of 90 percent of the sampled population) for the conservation of water and wildlife as well as the protection and preservation of ecologically important habitats and lands in Texas.
I had the pleasure of serving on the Bush task force and of heading the project research team for the Texas Tech study. Collectively, the two studies offer specific solutions that would position Texas as a leader in conservation and outdoor recreation and provide essential components of the quality of life that our citizens expect in the 21st century. If the recommendations are implemented as proposed, we will have a good chance of retaining our precious heritage of wildlife diversity and wide-open spaces.
The next one hundred years will likely decide the future of wildlife and open space in Texas. The decision will be made, either directly or indirectly, as to how much and what kind of nature survives. Conservation pressures will come from a variety of sources. Habitat loss and degradation from overdevelopment, overharvesting, introduction of exotic species, pollution, and other causes will continue to take a significant toll. Global warming or climatic change could exacerbate the loss and degradation of biodiversity by increasing the rate of species extinction, changing population sizes and species distributions, modifying the composition of habitats and ecosystems, and altering their geographic extent. Essentially the problem stems from proliferating human land uses that are powerfully changing the form and shape of the landscape.
Conserving wildlife, which recognizes neither ownership nor boundaries, calls for good science, first-rate technology, excellent management, and a broad constituency willing to make some concessions to save it. To maintain wildlife diversity into the next century will require financing, public support, and, above all, the integrated management skills that even the most sophisticated high-tech farming systems lack. We face a monumental task, far beyond our existing capabilities. But now is the time to look ahead, coordinate, and plan—before our options are further narrowed.