San Antonio Natural Area Parks
News & Articles

Nothing's Natural
(But We Try!)

Eric Lautzenheiser
Natural Areas Superintendent

 feral hog

Many scientists argue that nothing remains in this world in a "natural" state. Pollution has been found at the tips of the Earth's poles and in the depth's of the oceans. Here come the semantics. "Natural" is often used to mean a condition not impacted by human activity, ergo the natural world has been diminishing since the evolution of our species, and probably no longer exists. However, when most of us use the word "natural" in an environmental context we mean a condition little impacted by the effects of historic humans, mostly in the industrial and post-industrial age. We view the activities of pre-historic peoples as more in balance with natural. Be that as it may, it is true that every square inch of Bexar County is markedly changed by recent human activity and is being further impacted every day. The overall landscape and composition of vegetation is dramatically different than before Europeans arrived. Exotic plant and animal species abound and are replacing native species. New diseases have been introduced that affect native plants and animals. Much soil has been eroded. Urban sprawl covers most of the county with asphalt, concrete and artificial landscapes. The atmosphere has been polluted. Water tables are depleted, drying up creeks and springs. Bear, bison, wolf, beaver, ocelot and others have either disappeared from our region or gone extinct. Many species probably vanished before they were even described.

The parks and properties of the Natural Areas are no exception. Indeed those currently open for your use suffer from an additional impact - the love, overuse and occasional abuse of their visitors. Over 60,000 people are estimated to visit Friedrich Wilderness Park each year. Perhaps over a 100,000 visit Eisenhower Park. Walker Ranch Park has overflow capacity almost every weekend and many weekdays. We ask that visitors stay on the designated trails to preserve the parks, their vegetation and wildlife habitat. Most do, a few do not. In any case, such heavy use will have an impact.

The primary goal of the San Antonio Parks Department Natural Areas' staff is to preserve your natural heritage, as represented in the City's Natural Areas preserve system. This includes Walker Ranch, Eisenhower Park and Friedrich Wilderness Park as well as nearly five thousand new acres acquired under the Proposition 3 Edwards Recharge Protection Tax Initiative. Besides general upkeep and janitorial functions, our staff spends considerable resources and time in habitat management and restoration.

Our primary job is to mitigate all negative impacts to these properties, both current and historic. As trails are the primary vehicle for public use, they can sustain much wear each year and must receive a goodly amount of maintenance. The trails cannot be natural, that's a bit of an

oxymoron. Park trails are human creations; they do not exist naturally. In addition, without maintenance they will deteriorate and impact the overall system. When we finally achieved the resources to begin aggressive trail maintenance about five years ago, some of the trails in Friedrich Wilderness Park had eroded over five feet deep below natural grade! The erosion and loss of soils is obvious. Less obvious is how such channeled trails interrupt natural sheet flow of rainwater runoff and completely change the hydrology of extremely large areas. This in turn alters vegetation patterns, which triggers changes in animal populations. Our primary approach to trail maintenance is to fill eroded trails back to near natural grade using on-site soil and rocks, or purchased ground limestone from local quarries. The choice depends upon volume and location of repairs. Water bars (see Jayne Neal's article on Waterbars) and juniper log steps are added to further stabilize the trails and direct water runoff in as natural a pattern as possible.

Removal of aggressive, introduced plant species is our second highest priority. These plants have been introduced from the far corners of the world; thrive under our local conditions; multiply and displace native plant species, thereby altering the habitat for native animal species. Some have been introduced by accident and some escaped from ornamental landscapes. Many are still widely sold and planted today, aggravating the problem more and more. Wind, water, birds and other animals spread seeds. Bermuda grass, KR Bluestem grass, Johnsongrass, Ligustrum, Privet, Nandina, Pyracantha, Chinese Pistachio tree, Chinaberry tree, Chinese Tallow tree, Giant Reed, Tree of Heaven, Japanese Honeysuckle, Purple Trailing Lantana, Indian Lantana, Annual Rye grass, and Rescue grass are just a few of the worst offenders.

The two priorities above are "holding" tactics. These tactics are stabilizing existing conditions and working to prevent further deterioration. The last priority I will mention is the one closest to our hearts - restoration. Restoration is an attempt to improve or re-create environmental conditions that more closely resemble some previous "natural" condition. Herein lies one of the greatest debates among restoration ecologists.

Since the beginnings of restoration ecology in the 1930's, almost all U.S. practitioners have accepted the goal of restoration as re-creation aimed at pre-European settlement. However, a great body of evidence points to a significant influence by indigenous peoples on the American landscape first seen by European explorers. If we try to define an ecology prior to any human influence, we must return to the last ice age. That's about as unattainable and "un-natural" as creating a rainforest in Bexar County! The climate and environment have continued to change, both "naturally" and by human induced effects. We now have global warming which really throws a monkey wrench into the works. Instead of restoring to "what was", we may be faced with shaping "what will come." Moreover, we still have not come very close to agreeing on the basics of the first set of questions concerning classical restoration.

The Natural Areas currently address the classical approach to restoration as a means of re-creating a landscape and ecology that more closely resembles that which existed prior to European settlement. Our restoration efforts have taken two main forms.

In the first approach, we try to rebalance existing biological components. We focus on the plant communities. If this is done well the animal, insect and microbial communities will usually follow suite. Currently, all the Natural Areas are located in or at the edge of the Balcones Canyonlands (or Texas Hill Country). This area was a savanna before modern settlement. Much more grassland prevailed. These grasslands were dominated by grass species now much less common or even rare. Woody plants, especially Ashe juniper, have greatly expanded their dominance in the landscape. By removing some of the juniper and other woody plants in selected locations, we can preserve and expand the grassland component that has been disappearing. This creates a landscape closer to our defined "natural" conditions. It helps to preserves a suite of organisms that might otherwise vanish, including roadrunners, bobwhite, turkey, fox, many birds of prey, various native rodents and reptiles, untold butterflies and other insects, and hundreds of species of wildflowers and other herbaceous plants.

One way to look at an ecological system is to view it as a complex jigsaw puzzle. If you lose a few pieces, you can still make out the picture. If you lose too many, the picture may become totally incomprehensible (non-functional). You can still make out the picture quite well in the Natural Areas preserves. In the approach above, we are trying to save all the pieces we currently possess. The second approach to restoration undertaken by the Natural Areas is to replace some of the missing pieces. To date we have reintroduced plant species. These plants will provide habitat for insects and other organisms that may still be found in the region and that would depend upon these plants for their existence. Reintroductions to date include ladies'-tresses orchids, New Jersey tea, columbine, inland sea oats grass, water clover-fern, cardinal flower, nimblewill, rockrose, coralberry, American beautyberry, buttonbush, sawgrass, pigeonberry, goldenrod, spicebush, indigobush, creek plum and Mexican plum. I don't think we will ever reintroduce buffalo. (Surprisingly, last year, a bear and cub were seen at Friedrich Wilderness Park several times and by different individuals.) We have successfully recreated habitat for the Black-capped vireo at Friedrich Park. After vanishing from the park in the late 1980's, we have lured them back with our restoration efforts. Two pair nested in the park this year causing great excitement among staff and birders.

So, Natural Areas are actually highly managed areas. They are not just set aside and left alone. In many respects, preserves are as highly manipulated by human activity as an urban neighborhood. Natural Areas are un-natural - a paradox. Yet, without such management and manipulation we are sure to lose the greater part of our natural heritage.

Eric Lautzenheiser is the Nature Areas Superintendent for the City of San Antonio Parks and Recreation Department. He oversees the Natural Area Parks and Edwards Aquifer Protection preserves.

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