PARENT SESSION
Oral Session #75: Plant Communities: Vegetation Analysis. Presiding: J. Fralish.
Friday, August 10, 2001. 8:00 AM to 12:00 PM. Hall of Ideas F.
Comparison of the vegetation and soil composition of Prosopis glandulosa and Larrea tridentata communities of the Diamond Y Spring Preserve in west Texas.
Hart, Dianne1, Van Auken, O.W.1, 1
ABSTRACT- The Diamond Y Spring Preserve in Pecos county, Texas contains a salt marsh and is located in the northern Chihuahuan desert. It is owned by the Nature Conservancy of Texas. The spring and marsh area support 2 federally endangered species of fish, several rare snail species and the threatened puzzle sunflower, Helianthus paradoxus. Woody plant communities of honey mesquite, Prosopis glandulosa, border the marsh area. Typical Chihuahuan desert vegetation consisting largely of creosote bush, Larrea tridentata, exists at higher elevations and further from the marsh. Elevation transects were established from the marsh to the highest elevations of the preserve. Woody and herbaceous plants were identified along these transects using the line point method. Plant composition of ten Prosopis and ten Larrea communities was determined. Density, species density, frequency and canopy area were calculated for each community with the quadrat method. Cover of rock and herbaceous plants was measured in each quadrat along the transects. Surface soil samples were taken from each community. The soil factors examined were soil depth, salinity, concentrations of major anions and cations and soil particle size. The soil pH is slightly alkaline in both communities. Soil depth, salinity, concentrations of magnesium, phosphorus, potassium, nitrate, chloride and sulfate are higher in the Prosopis communities. The Larrea communities were generally characterized by sandier soil and lower salinity.
KEY WORDS: vegetation analysis, Chihuahuan desert, Prosopis glandulosa, Larrea tridentata