The occurrence of Gutierrezia sarothrae on Bouteloua eriopoda ranges in southern New Mexico

Campbell, R; Bomberger, E

Bouteloua eriopoda, the most important forage grass in southern New Mexico, and of considerable value as range forage throughout the semi-arid southwest, is subject to serious depletion as a result of drought or overgrazing or both. Its revegetation ordinarily is quite slow because it reproduces poorly by seed, and migrates almost entirely by vegetative processes. Gutierrezia sarothrae has been observed to replace the Bouteloua on areas continually overgrazed. This dominance of the worthless shrubs is due largely to the fact that usually they are not relished by range livestock under ordinary conditions, while the palatable forage grasses may be killed entirely by injudicious grazing, especially during drought. Nevertheless, these shrubs have a definite soil protective value. A study of the occurrence of G. sarothrae in a representative B. eriopoda association on gravelly sand was started in 1924. The area had been badly depleted by severe drought and some overgrazing. Three quadrants, each containing three square meters were established and charted every year from 1924 to 1930 inclusive. On the first quadrant, several well established young G. sarothrae plants were present in 1924, but B. eriopoda was dominant. In spite of attacks by insects in 1925 and 1927 nearly 31 percent of these plants were alive in 1930, but no new seedlings survived, although many appeared. As a final result of generally above average rainfall and light grazing, the Bouteloua area was nearly 5 times greater and the Gutierrezia area nearly two times greater in 1930 than in 1924. On the second quadrant, the Bouteloua was decidedly dominant in 1924 and only a few seedlings of Gutierrezia were present. 62.5 percent of the young shrubs survived, while only one new seedling of four became established. By 1930, the Bouteloua tuft area was nearly 6.5 times greater, and the Gutierreza area over 3 times greater in 1924. The last quadrant supported some B. eriopoda, but l

The occurrence of Gutierrezia sarothrae on Bouteloua eriopoda ranges in southern New Mexico

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