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The primary focus of the study area is on a 2,000-hectare ranch and surrounding lands in northeastern New Mexico, approximately 30 kilometers (20 miles) to the northwest of Nuevo Laredo, Tamaulipas.  The full extent of the study area is approximately 12,000 ha. (30,000 ac.), bounded roughly by the town of Hidalgo, Coahuila at the northwestern corner and the town of Colombia, Nuevo Leon at the southeastern corner, with the Rio Grande as the northern boundary.  This area is bounded by the following latitude and longitude lines (including only the Mexican lands within this boundary):

Northern Limit - 27° 48" N
Southern Limit - 27° 41" N
Western Limit  - 99° 53" W
Eastern Limit  - 99° 45" W

 The study area was analyzed at two levels of resolution.  First, general characteristics were analyzed for the full extent of the study area, based on existing data.  Second, a more detailed analysis, including extensive field investigation, was conducted for the specific property named "Rancho San Eduardo," the 2,000-ha. ranch bordered by the Rio Grande to the northeast and the Riverine Highway to the southwest. 

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Absolute elevation in the study area ranges from approximately 130 meters above mean sea level near the Rio Grande, to 190 meters in the areas farthest from the Rio Grande. The study area is characterized by flat to gently sloping terrain varying from approximately 0.5% to 3% for most of the area. The terrain is much steeper and more varied in the area within about 100 meters of the Rio Grande, including several irregular features such as riverbank and terrace deposits and weathered sandstone outcroppings several meters high and wide. 

Within the Rancho San Eduardo, there are also isolated hills up to 30 meters in height with steep
sideslopes of 2:1 or greater slope in some areas. Some of these hills are marked by irregular, weathered sandstone features. Several large arroyos also provide significant topographical relief within the ranch property. Many of the arroyos have nearly vertical sides, with bottom widths varying from approximately 1 to 15 meters, depending on the soil characteristics and contributing drainage
area at each location. Several man-made earthen dams have been installed along these arroyos to create tanks for livestock. Many of these dams also serve as roadway embankments, with top widths of approximately 6 to 10 meters. 

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Geology and Geomorphology
The geology of the study area consists of different layers of sandstone of tertiary age (eocene, about 50 million years before present). The area has to be seen in the geologic context of a stratified system of nearly horizontal layers dipping gently towards the Gulf of Mexico from the Big Bend area to the Gulf, where the layers come to the earth's surface in a systematic order from paleozoic and older age in the lowest levels (more than 300 million years old) to holocene (present) in the uppermost levels, respectively.

This parent material has been shaped by different forces. The most geomorphologically active force in the study area is water, which has two effects, erosion and accumulation. The Rio Grande valley itself is an erosional form and at the same time it represents the local erosion base (pediplain), collecting all contributory runoff water from the study area. This water cuts arroyos, large in number and depth, into the surface leading to valleys up to 10 or more meters depth and up to 2000-plus meters in length). Other features are steep hillside slopes in the area and at least two river terraces along the Rio Grande. Accumulation features could only be found in the form of fillings in the arroyo bottoms. These fillings consist of the eroded material from the surrounding area and from the arroyo sideslopes. At the highest points in the area (over 180 meters above sea level) a conglomerate can be found that forms a wide gravel field in its eroded state on the surface.

  • H.B. Renfro: Geological Highway Map of Texas. United States Geological Highway Map Series. Tulsa, OK, 1979 

  • Bureau of Economic Geology: Geology of Texas, Austin, 1992.

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The study area is generally composed of arid, sandy desert soils without definite horizons. Visual observations from the field showed cemented calcium carbonate is present in many areas. Some of the soils appeared leached and in the wetter areas, dark cracking sandy clay soils were present. Areas along the bank and bed of the Rio Grande consist of alluvial or valley bottom sandy soil. According to the soils map, there is a large area east of the town of Colombia that is composed of caliche, or cemented calcium carbonate material.

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Land Cover and Vegetation 
The native vegetation of the study area is mainly composed of shrublands and grasslands, both of which are common vegetation types in regions with arid climates.  Because a significant portion of the study area is farmed or used as pastureland, and has a long history of being used for such purposes, the native vegetation is confined to small areas that have not been disturbed.  Map data from 1978-1982 indicate that such areas are distributed sporadically throughout the study area.  However, recent fieldwork indicates that the native vegetation is usually found in areas unsuitable for farming, such as sandstone outcrops or areas with an abrupt topography.

The native shrublands of the study area are mainly composed of thorny shrubs, shrubs without thorns, or a combination of the two shrub types.  In some areas, shrublands are mixed with the native grasslands.  The most prominent native tree of the region is the mesquite (Prosopis glandulosa Torr.), which is well adapted to arid climates and is a successful pioneer species that can rapidly colonize abandoned agricultural fields.  In the area, it is common to find areas dominated by mesquite trees, and these areas are generally referred to as mezquitales.  Prickly pear cacti (Opuntia spp.) are also prominent elements of the native vegetation, and in some areas they can be the dominant species. These areas are commonly known as nopaleras.  Although distinct shrublands, grasslands, mezquitales, and nopaleras can be identified in the region, there are also areas where elements of all vegetation types coexist in different degrees and which cannot be classified into a single vegetation category.

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Water Resources
The Rio Grande, which flows in a NW-SE direction towards the Gulf of Mexico, is the main water feature in the study area. A series of natural intermittent water features (creeks, washes, gullies,  arroyos, etc.) within the region drain into the Rio Grande.  Some of these features within the San Eduardo property drain primarily into large water tanks, which are human-made for the purpose of irrigation and agriculture. Because the area is characterized by arid uplands, the creeks and arroyos are dry most of the year.

Rancho San Eduardo also boasts an extensive man-made water distribution system for household and irrigation purposes.  This system uses water from three sources: the Rio Grande, the Carrizo-Wilcox sand aquifer, and rainfall.  Two electric pumps, with pumping capacity of 3,000 gallons per minute, are operated at the bank of the Rio Grande to fill the large water tank and provide water for household uses.  This water is also conducted via irrigation channels and pumps to several other water tanks in the central area of the ranch.  A new 400-foot well with 500-gpm pumping capacity is operational and has the capacity to provide substantial water for agricultural and other uses.  Groundwater pumps, some run by windmill, have largely been abandoned because the water is too salty for cattle.  Finally, several earthen dams have been created to store rainfall for livestock watering.  

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Cultural Features
The study area includes two towns: to the northwest is Villa Hidalgo in the state of Coahuila, and to the southeast is Colombia in the state of Nuevo Le
ón. Both are relatively small in terms of size, and the areas outside the towns appear to be scarcely populated with only a few isolated structures (either houses or abandoned buildings).  With the exception of the towns, the land in the study area is used for agricultural or cattle-ranching purposes. 

 A dirt road which is only passable during the dry season runs southeast from Villa Hidalgo for approximately 1.35 miles, at which point it becomes an all-season dirt road. The latter runs in the same southeast direction, but does not pass through Colombia. A system of trails (both wide and narrow) crisscrosses the study area, connecting ranches and agricultural fields. A wide trail perpendicular to the main all-season dirt road provides access to the town of Colombia.

 An electricity line of 34.5 Kv runs through the study area in a northwest-southeast direction. The line serves Villa Hidalgo and Colombia, and it also branches at two points between the towns towards the Rio Grande.

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Land Uses and Practices
in the study area is primarily agricultural, with some residential development in Hidalgo and Colombia, and limited parkland along the Rio Grande near Hidalgo.  Industrial uses are also expanding in the area between Colombia and the Colombia-Solidaridad International Bridge. Agricultural land is predominantly used for ranching, although farming is practiced on the ejidos along the eastern boundary of the San Eduardo property. 

Within the ranch, land is subdivided with a fence system for range management purposes.  Nearly all of the land is strictly grazing land, although two large circular fields were once used for cotton cultivation and are still irrigated for hay crops.  Some grazing areas of the ranch have been closed off to cattle to allow deer populations to expand.  The abundance of deer attracts recreational hunters, in what has become a profitable enterprise.  Hunters and other guests are housed at the main ranch house, alongside the large water tank.  This area also includes ranch employee residential buildings and farm equipment storage and service buildings.

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Botanical Exploration in the Laredo Region in the 19th Century
In 1826, the Swiss botanist Jean Louis Berlandier (ca. 1805-1851) was sent to Mexico by his patron,  Auguste-Pyrame DeCandolle, with the express purpose of collecting plant specimens and seeds for the Museum of Natural History in Geneva.  At the time of Berlandier’s arrival in Mexico, the boundary between the newly established Mexican Republic and the United States was not clearly delimited.  It was an issue that caused great political unrest between the two countries. To resolve this issue, the Mexican government decided to send a Commission to Texas to survey the territory and establish the boundary limits between the two nations. Among the members of the Commission were a mineralogist, a cartographer, and Berlandier, who traveled with the commission in the capacity of botanist. The first region that Berlandier explored in what is today Texas was Laredo, known at that time as Villa de San Agustín de Laredo, or the Presidio de Laredo (established ca. 1755), and which was part of the Mexican state of Tamaulipas.  According to Berlandier, the vegetation around Laredo was “quite miserable” and in the description of his journey to this region, he only mentions that the huisache is the most prevalent tree, and that the ground is generally covered by small bushes.  It appears as though Berlandier was anything but impressed by the landscape of the Laredo region, as he makes no further comments on its characteristics. However, the journey narrative is quite informative about the inhabitants of Laredo (who they were, what they lived on, etc.); and the climatic, soil, and geological characteristics of the area. Berlandier also mentions the problems that that Rio Grande presents to the natives (such as constant flooding), noting as well that in the Laredo region, the banks of the river “present nothing but a horrifying aridity.” A significant portion of the narrative is dedicated to criticizing the native’s “laziness” and mismanagement of the land in the region.  Some comments are made about the Indigenous people Berlandier saw in Laredo, such as the Lipans and the Comanches, who he found to be at once “barbarous and nomadic.” Berlandier notes that one of the main food sources of these Indians was bison.

The Boundary Commission remained in Laredo between the 2nd  and 19th of February of 1828, and from July 28th to August 11th  of the same year. It appears that the time spent by Berlandier in Laredo was not fruitful in terms of botanical exploration. However, Berlandier explored many other Texan regions and is today considered the first person to have carried out extensive botanical research in Texas. Interesting to note is the fact that Berlandier’s work appears to have never satisfied the high standards expected of him by his Genevese patron, DeCandolle.  Nevertheless, Berlandier contributed a significant number of plant specimens to different herbaria, which helped botanists recognize the uniqueness of the Texan flora. Berlandier never returned to Europe, and instead settled in Matamoros where he married a Mexican woman, ran a pharmaceutical business, and practiced medicine.

From the material we have on Berlandier, it is clear that in the recent past (at least 175 years) the vegetation of the Laredo region has not been much different than what it is today: the region is arid, the diversity of plants is limited. However, we do learn that the habitat of the Laredo region in the 19th century was suitable for animals such as bison, which today no longer roam through the region.  


  • Berlandier, J. L. (1980) Journey to Mexico during the years 1826 to 1834. Vol. III, pp. 262-270.  Austin: Texas State Historical Association. 

  • Emory, William H. (1857) Report on the United States and Mexican boundary survey made under the direction of the Secretary of the Interior (Vol. 1 and 2) Washington, DC: Cornelius Wendell, printer.

  • Geiser, S. W. (1948) Naturalists of the Frontier. Dallas: Southern Methodist University. 


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Prepared by the Community and Regional Planning Program, University of Texas at Austin, Spring 2000