An annotated vascular flora and floristic analysis of the southern half of the Nature Conservancy Davis Mountains Preserve, Jeff Davis County, Texas, U.S.A.

Abstract

The Nature Conservancy Davis Mountains Preserve (DMP) is located 40 km northwest of Fort Davis, Texas, in the northeastern region of the Chihuahuan Desert and consists of some of the most complex topography of the Davis Mountains, including their summit, Mount Livermore, at 8378 ft (2554 m). The cool, temperate, "sky island" ecosystem caters to the requirements that are needed to accommodate a wide range of unique diversity, endemism, and vegetation patterns, including desert grasslands and montane savannahs. The current study began in May of 2011 and aimed to catalogue the entire vascular flora of the 18,360 acres of Nature Conservancy property south of Highway 118 and directly surrounding Mount Livermore. Previous botanical investigations are presented, as well as biogeographic relationships of the flora. The numbers from herbaria searches and from the recent field collections combine to a total of 2,153 voucher specimens, representing 483 species and infraspecies, 287 genera, and 87 families. The best-represented families are Asteraceae (89 species, 18.4% of the total flora), Poaceae (76 species, 15.7% of the total flora), and Fabaceae (21 species, 4.3% of the total flora). The current study represents a 25.44% increase in vouchered specimens and a 9.7% increase in known species from the study area’s 18,360 acres and describes four endemic and fourteen non-native species (four invasive) on the property. The subsequent analysis of the results, compared to those of previous regional-flora catalogues, presents the flora of the DMP as one that is unique to the higher elevations and igneous substrates of western Texas and the northern Chihuahuan Desert. Multiple influences from overlapping and neighboring ecoregions, including the Great Plains, Madrean, and Sonoran provinces, are all seen to have varying degrees of authority in regards to the shaping of the modern-day vegetation.