Igneous geology of the Davis Mountains, west Texas: II. Volcanic rocks of the Ft. Davis area, Davis Mountains

1989 ◽  
pp. 141-146
Author(s):  
C. H. Henry ◽  
J. G. Price
Keyword(s):  
Volcanic Rocks ◽  
West Texas ◽  
Davis Mountains

Fire regimes of the piñon–juniper woodlands of Big Bend National Park and the Davis Mountains, west Texas, USA

2009 ◽  
Vol 39 (6) ◽  
pp. 1236-1246 ◽  
Author(s):  
H.M. Poulos ◽  
R.G. Gatewood ◽  
A.E. Camp
Keyword(s):  
National Park ◽  
Fire Regime ◽  
Fire Regimes ◽  
Climatic Conditions ◽  
Tree Regeneration ◽  
Big Bend National Park ◽  
Fire Scar ◽  
West Texas ◽  
Big Bend ◽  
Davis Mountains

While piñon woodlands cover much of arid North America, surprisingly little is known about the role of fire in maintaining piñon forest structure and species composition. The lack of region-specific fire regime data for piñon–juniper woodlands presents a roadblock to managers striving to implement process-based management. This study characterized piñon–juniper fire regimes and forest stand dynamics in Big Bend National Park (BIBE) and the Davis Mountains Preserve of the Nature Conservancy (DMTNC) in west Texas. Mean fire return intervals were 36.5 and 11.2 years for BIBE and DMTNC, respectively. Point fire return intervals were 150 years at BIBE and 75 years at DMTNC. Tree regeneration in west Texas piñon–juniper woodlands occurred historically during favorable climatic conditions following fire years. The presence of multiple fire scars on our fire-scar samples and the multicohort stands of piñon suggested that low intensity fires were common. This study represents one of the few fire-scar-based fire regime studies for piñon–juniper woodlands. Our results differ from other studies in less topographically dissected landscapes that have identified stand-replacing fire as the dominant fire regime for piñon–juniper woodlands. This suggests that mixed-severity fire regimes are typical across southwestern piñon forests, and that topography is an important influence on fire frequency and intensity.

scholarly journals Polyploidy and genome size variation in Phlox nana (Polemoniaceae) from the Pecos plains of New Mexico and the Davis Mountains of West Texas

2017 ◽  
Vol 11 (2) ◽  
pp. 351-362
Author(s):  
Jamie Ladner ◽  
Mark H. Mayfield ◽  
L. Alan Prather ◽  
Carolyn J. Ferguson
Keyword(s):  
New Mexico ◽  
Genome Size ◽  
Size Variation ◽  
Chromosome Counts ◽  
Genome Size Variation ◽  
Ploidy Levels ◽  
West Texas ◽  
Popula Tions ◽  
Davis Mountains ◽  
Parapatric Distribution

Polyploidy is conspicuous in the genus Phlox, and some species exhibit variation in ploidy levels, or cytotypic variation. Diploid, tetraploid and hexaploid popula-tions of P. nana occur across parts of the species distribution in the southwestern United States and northern Mexico. A recent study highlighted two areas for which ploidy level inferences were challenging: a population on the Pecos Plains of New Mexico (“Caprock”) and the Davis Mountains region of West Texas. Plants in these areas were sampled and chromosome counts and flow cytometry methods were used to assess ploidy levels and genome sizes. Homoploid variation in ge-nome size was unambiguously documented: the genome size of tetraploid plants from the Davis Mountains was significantly larger than that of plants from Caprock. The general condition of larger genome sizes for plants in the Davis Mountains explains previous difficulty in determining ploidy levels within the region. Most plants at the Caprock population appeared to be tetraploid (2n=28), but chromosome counts revealed variants, including some putative pentaploids. Within the Davis Mountains region, both diploid (2n=14) and tetraploid (2n=28) cytotypes were documented, with a parapatric distribution. Overall, this study clarifies patterns of cytotypic diversity in P. nana, highlights an example of infraspecific, homoploid genome size variation, and contributes to a framework for ongoing evolutionary investigation in this study system.

scholarly journals Outlier Stands of Quaking Aspen in the Davis Mountains of West Texas: Clone or Clones?

2014 ◽  
Vol 05 (15) ◽  
pp. 2298-2311
Author(s):  
Jerritt Nunneley ◽  
O. W. Van Auken ◽  
John Karges
Keyword(s):  
Quaking Aspen ◽  
West Texas ◽  
Davis Mountains
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