Dr. Geoffrey Stanford, President of the Native Prairies Association of Texas and Director Emeritus of the Dallas Nature Center recently submitted a speculative paper to the Native Plant Society conference concerning whether or not the terrain of Duncanville, Cedar Hill and surrounding communities qualifies as a new and unique Biome. Dr. Stanford speculates that areas that are now predominately bare limestone outcrops were once completely covered with dense tallgrass prairie and forest. The destructive influence of intensive farming followed by ranching lead to extensive erosion from which the land is now slowly recovering. This previously devastated landscape is now host to its own particular flora and fauna. Should this local ecology, of recent origin be viewed as an independent biome?

What does biome really mean anyway? Ecological terms used to describe different areas are often vague and tend to overlap. When does a community become large enough to be labeled a biome? In its most general definition, biome refers to a particular region with characteristic climate, physical factors and plants and animals that are adapted to those conditions. The area we live in should properly be known as Temperate Deciduous Forest. We receive just enough rain(~34-36 inches per year) to support large stands of trees. When rainfall drops below a certain level (<32 inches according to Dr. Stanford’s report) trees give way to the Grassland Biome. Should this transition zone be characterized as a separate biome, an ecosystem, or labeled as an extended community?

The term Biome also refers to a major regional ecological community in a climax state. It can be argued that as a result of settlement, development and urbanization, there are very few areas around us to indicate what biome we really belong to. This is an age begging for new biome labels. The rainforestless biome, the humanopolis biome, the monocultural biome (for extended farming regions) and possibly as Dr. Stanford suggests, a bare rock biome. Perhaps these reflect climax communities after all. Why speculate on what the land would look like if we left it alone when we probably will not.

The question I had was this: Are these wide open patches of limestone a recent phenomenon resulting from human destruction or have they lain exposed for long ages--a product of weathering of this type of landform? Searching old literature turns up these descriptions regarding the past appearance of our Eastern Cross Timbers physiographic region: "....this easternmost timbered stretch was a physical obstacle for travelers, but a source of wood for settlers. Until the 1870’s the Eastern Cross Timbers was the so-called frontier--westward lay the huge expanse of prairies and open plains." (Doughty, 1983). This rough country did not succumb easily to the increasing human presence; 50 years later it was portrayed this way: "The southwestern face of the cuesta (escarpment), along which runs Mountain Creek, is steep and rough. It is known as the cedar brake country. Streams finger back into the edge of the escarpment, forming steep, narrow gulches, covered with heavy scrub timbers, which even yet form a haven for wolves and other wild animals." (Shuler, 1918). Richard Phelan sums it up well by stating: "The woods called Cross Timbers, East and West, are small, frayed, and partly forgotten, the most nearly wiped out of all the physiographic regions of Texas. I suspect that in this century many people have grown up in the Cross Timbers without knowing they were doing so, for millions of acres of the original post-oak and blackjack woods have been cut down and made into farmland." So Was there bare limestone or wasn’t there? Due to the amount of rainfall and abundant vegetation, it probably wasn’t bare.

If large parcels of land on and around the White Rock Escarpment are protected for long periods of time will the Chalkland Prairie Biome need to be relabeled as the Cedar Brake Biome of the future? Will it return to what it was in the past--mainly tall grass prairie bordered by stands of cedar brakes and post oak Savannah’s?

The trend in environmental protection seems to be moving away from endangered species protection to a more broad protection of flora and fauna rich habitats. From an ecological standpoint, transition zones from one community to another (as we find occurring at the contact between the Austin chalk and the Eagleford shale) are the richest habitats, filled with myriad plant and animal species. And so we find the escarpment even today--a stubborn, scrubby sort of biome(?) snubbing its nose at us, still untamed, waiting for us to save it from us.

Reference:

Doughty, Robin W. Wildlife and Man in Texas - Environmental Change and Conservation. College Station, Texas: Texas A&M University Press, 1983. p.6

Phelan, Richard. Texas Wild. New York, New York: E.P. Dutton & Co, 1976. p.132

Shuler, Ellis W. The Geology of Dallas County. Austin, Texas: Bureau of Economic Geology and Technology, University of Texas Bulletin no. 1818, March 25, 1918. P.10

Natural History of North Central Texas Index
 

Royce & LuCretia Milam Copyright © September 1995 Wild Vision. All rights reserved.