Past and Present Grasslands of Southern Texas and Northeastern Mexico

Johnston, Marshall

Accounts of the middle of the last century show the prevalence of low, woody vegetation in southern Texas and northeastern Mexico. Relatively limited areas near the coast were grasslands, including the coastal prairies and large parts of the Wild Horse Desert or Eolian Plain. The small Loreto caliche-sand plain of coastal Tamaulipas, judging by present vegetation, was also largely grassland. The present vegetation of the Kleberg clay prairies near the coast in southern Texas includes low grasses of the genera Buchloδ, Chloris, and Hilaria. In prairies on sandy soil in southern Texas, including the Ingleside and Kennedy sand prairies of the Wild Horse Desert, Andropogon scoparius var. littoralis is abundant or dominant where not removed by grazing. The Loreta grasslands are unique in that Bouteloua radicosa is abundant in them. A relatively limited proportion of the areas which were grassland about 100 years ago are now occupied by low woody vegetation, including the southern part of the coastal prairie in Texas, of which the Kleberg clay prairies are remnants. The grasslands of sandy soils have apparently diminished in area both by peripheral shrinkage and expansion of internal mottes. In many areas the woody vegetation is now thicker and more nearly exclusive of grasses and forbs than formerly. It is emphasized that many 'grasslands' were infested with the ubiquitous mesquite, Prosopis glandulosa, in a stunted growth form long ago, and that the rapid takeover of the mesquite bush involved increase in stature of the aerial parts of the plant and in density of stand, rather than invasion of previously brush-less areas. Similar changes have occurred elsewhere. Most authors feel the control of fires explains the shrinkage of grassland. Nothing in this study contradicts such an explanation.

Past and Present Grasslands of Southern Texas and Northeastern Mexico

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