Abstract
This research compared surveys of vegetation that were conducted in Big Bend National Park, Brewster County, Texas, during 1955–1960 and 1968–1969 with data collected in 2005 and 2006. Comparisons were based on percentages of cover and flora at five study sites. Results suggest some increases and decreases in certain types of vegetative cover since creation of the park, although no trend was consistent across elevations and years. Sites at lowest and highest elevations had significant increases in shrubs. Except for one, all sites had significant differences in total cover. Some species had changed in overall abundance. Lehmann lovegrass (Eragrostis lehmanniana) was becoming a dominant grass in foothills of the Chisos Mountains and surrounding Chihuahuan Desert. In contrast, leatherstem (Jatropha dioica), fragrant sumac (Rhus trilobata), tarbush (Flourensia cernua), four-wing saltbush (Atriplex canescens), desert hackberry (Celtis pallida), and Mexican mock vervain (Glandularia bipinnatifida) had disappeared from some, or all, locations where they were recorded previously.
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