Davis Mountains Research Articles

Avian haemosporidians of breeding birds in the Davis Mountains sky-islands of west Texas, USA.

Avian haemosporidians are protozoan parasites transmitted by insect vectors that infect birds worldwide, negatively impacting avian fitness and survival. However, the majority of haemosporidian diversity remains undescribed. Quantifying this diversity is critical to determining parasite–host relationships and host-switching potentials of parasite lineages as climate change induces both host and vector range shifts. In this study, we conducted a community survey of avian haemosporidians found in breeding birds on the Davis Mountains sky islands in west Texas, USA. We determined parasite abundance and host associations and compared our results to data from nearby regions. A total of 265 birds were screened and infections were detected in 108 birds (40.8%). Most positive infections were identified as Haemoproteus (36.2%), followed by Plasmodium (6.8%) and Leucocytozoon (0.8%). A total of 71 haemosporidian lineages were detected of which 39 were previously undescribed. We found that regional similarity influenced shared lineages, as a higher number of lineages were shared with avian communities in the sky islands of New Mexico compared to south Texas, the Texas Gulf Coast and central Mexico. We found that migratory status of avian host did not influence parasite prevalence, but that host phylogeny is likely an important driver.

Four new species of Phytocoris Fallén (Hemiptera, Miridae) from the Davis Mountains in Texas and further documentation of known species of Jeff Davis County.

A recent survey of the entomofauna of the Davis Mountains in the state of Texas has revealed four new species in the genus Phytocoris Fallén (Miridae, Mirinae, Mirini): Phytocorismcivorsp. nov. and Phytocorisschmitzisp. nov. found on Quercusgrisea Liebmann, and Phytocorismarquasp. nov. and Phytocorisrileyisp. nov. found attracted to lights. Descriptions, habitus, and genitalic images for the new species are included herein. Further, habitus and genitalic photographs of known Phytocoris species from the county are included to aid in identification.

Geochemical evolution of the Paradise Mountain Caldera complex, Davis Mountains: Implications for the tectonic and magmatic evolution of Trans-Pecos Texas and adjacent Mexico

The Paradise Mountain Caldera (~20 × 14 km), located west of Fort Davis, Texas, produced two major ignimbrite/lava complexes at ~36.2 and 35.9 Ma. The older unit (Fort Davis Tuff) is composed of rheomorphic tuff and overlying chemically similar lava. The younger unit (Wild Cherry Tuff) forms thick intracaldera deposits and an outflow sheet that spread over an estimated 2000 km2. Near the caldera, the two ignimbrites are separated by trachytic lava of the Mount Locke Formation. The 5-km diameter Point of Rocks intrusion, which crops out within the eastern margin of the caldera, may have fed the Mount Locke flows. Wild Cherry Tuff is overlain by silicic lava (Casket Mountain Formation, ~35.8 Ma), with which is shares chemical similarities. Intracaldera Wild Cherry Tuff was intruded by silicic intrusions and locally intensively silicified and kaolinized. In a revision of stratigraphic nomenclature, we assign all of the above volcanic units to a Barrel Springs Group.Collectively, the above units form a series ranging from trachyte to alkali rhyolite. Glomeroporphyritic trachyte of Mount Locke lavas represents silicic melt incompletely segregated from more mafic material within a source magma chamber. Variation between Mount Locke Formation trachyte and Fort Davis Tuff rhyolite can be modelled by fractionation of a mineral assemblage of plagioclase, clinopyroxene, FeTi oxides, and apatite; variation within the two major tuff units can be modelled almost exclusively by alkali feldspar. Central eruption within the caldera produced intracaldera tuff more evolved than most of its outflow. Alkali rhyolite of the Wild Cherry Tuff and Casket Mountain lavas, although similar in major element chemistry and mineralogy, show wide variation in incompatible trace elements, suggesting that evolution of silicic magmas in terms of major element chemistry had reached an impasse due to fractionation of a mineral assemblage whose bulk composition was similar to that of parental rhyolite.Paradise Mountain units represent a transition from alkalic magmatism in northeastern Trans-Pecos Texas to metaluminous to peraluminous magmatism in southwestern Trans-Pecos Texas and adjacent Mexico. Over a span of 10 Ma, silicic magmatism terminated southwestward over this region at a rate of about 24 km/Ma. This termination may reflect continued foundering of a sinking Farallon slab and associated asthenospheric mantle upwelling. Mafic magma derived by melting of lithospheric mantle formed plutons that, through filter pressing of silicic magma from crystalline mush, generated silicic melts. The transition across the Trans Pecos region from alkalic to metaluminous magmatism may have resulted through preferential modification of lithospheric mantle along the easternmost extent of Laramide subduction.

Reconstruction of Piñon–Juniper Woodlands in the Sky Islands of the Davis Mountains, Texas, USA

Piñon (Pinus spp. L.)–juniper (Juniperus spp. L.) woodlands’ historical stand structures were recreated to provide reference conditions and document long-term changes in the Sky Islands of the Davis Mountains, Texas. Restoration of these isolated woodlands requires insights into the range of variability in current and historical stand structures, as well as an understanding of the spatiotemporal establishment and recruitment patterns of tree species. With drastic changes in forests and woodlands of the Southwestern United States widely reported, the main objective of this study was to reconstruct woodland tree temporal and spatial establishment patterns. A stratified random sampling approach was used to select two study sites each of 3600 m2 in area. Within each site, all individual trees were mapped, measured, and cored for age determination. Age and tree location data were used to recreate the spatiotemporal patterns of tree species establishment and recruitment. Increments in density of both Mexican piñon (Pinus cembroides var. cembroides Zucc.) and alligator juniper (Juniperus deppeana var. deppeana Steud.) reached 422 trees ha−1 in the 115-year period between 1890 and 2005; a yearly increment of 4 trees ha−1 that did not reflect a rapid rate of change in these piñon–juniper woodlands. Age distributions reflected the multi-cohort nature of these woodlands, and spatial autocorrelation measures were useful in the objective delineation of these cohorts. Temporal and functional niche differentiation of juniper was reflected in the development pattern where alligator juniper served as a pioneer species, exhibited a longer period of substantial recruitment, and had greater recruitment rates than that of Mexican piñon. Recruitment of Mexican piñon and alligator juniper occurred in an episodic fashion, with the majority of recruits being acquired between 1890 and 1949.

Multiple wildfires with minimal consequences: Low-severity wildfire effects on West Texas piñon-juniper woodlands

Piñon-juniper (PJ) woodlands comprise an important and extensive dry-site forest cover-type that has historically experienced high spatiotemporal variation in fire frequency and extent. We re-measured a network of permanent monitoring plots in a fire-suppressed PJ site the Davis Mountains of West Texas after prescribed fire (Rx) treatments and three subsequent wildfires to 1) quantify wildfire effects on PJ woodland stand structure and fuel loadings, and 2) evaluate the effects of Rx fires followed by wildfire. Although fire weather was extreme during the wildfire years, all three wildfires burned as low-severity fire events. Simultaneous autoregressive modeling revealed that total tree density and basal area declined significantly (P < 0.05) over the time-series, while surface fuel loadings increased significantly (P < 0.05), likely in response to fuel inputs from fire-induced tree mortality. However, tree mortality largely occurred in smaller tree size-classes (i.e. < 25 cm diameter at breast height). Neither fire severity, nor changes in stand structure varied significantly over the time-series among recent fire history types (i.e. no fire, Rx fire only, Rx fire + wildfire, or wildfire only) indicating that Rx fires had little effect on subsequent wildfire effects on forest structure or species composition. The low-severity nature of these recent wildfires under severe fire weather and in the wake of almost a century of fire suppression suggests that just because fires have been absent from a site for decades contemporary wildfires will not always result in fire regime characteristics that differ from historical fires in PJ-dominated areas.

SPATIAL ECOLOGY AND HABITAT UTILIZATION OF MONTEZUMA QUAIL IN THE DAVIS MOUNTAINS OF TEXAS

AbstractMontezuma quail (Cyrtonyx montezumae) occur throughout the desert mountain ranges in the Trans-Pecos of Texas as well as Arizona, New Mexico, and Mexico. Limited information on life history and ecology of the species is available due to the cryptic nature of the bird. Home range, movements, and preferred habitats have been speculated upon in previous literature with the use of observational or anecdotal data. We used innovative trapping techniques and technologically advanced radio transmitters to assess these ecological parameters for Montezuma quail. The goal of this study was to monitor Montezuma quail to determine home range size, movements, and habitat preference for the Davis Mountains population. We captured a total of 72 birds over the course of two years (2009 – 2010) (36M, 35F, 1 Undetermined). Thirteen individuals with &amp;gt;25 locations/bird were used to estimate the home range, movement, and habitat selection analyses. Home ranges (95% kernel density estimators) averaged 12.83 ha and varied greatly (0.02 – 43.29 ha). Maximum straight-line distances between known locations within home ranges varied from 0.73 – 14.83 km. Distances of movements were greater than previously reported. Preferred habitats consisted of Canyon Mountain Savannah and Foothill Slope Mountain Savannah across three spatial scales. Although our study was able to address some basic ecological attributes of Montezuma quail, additional research is warranted to better understand their population dynamics.

Some Lessons Learned on Early Survival and Growth of Containerized, Locally-Sourced Ponderosa Pine Seedlings in the Davis Mountains of Western Texas, US

The ponderosa pine forests in the Davis Mountains of western Texas recently experienced a major mortality event caused, in part, by an extended regional drought that predisposed trees and stands to mortality from both western pine beetle and wildfires. The loss of many overstory pines and the scarcity of natural ponderosa pine regeneration pose a considerable challenge to restoration. A commissioned study investigated artificial regeneration using containerized ponderosa pine seedlings with multiple planting seasons and vegetation management alternatives. Early survival was statistically greater for dormant season plantings than monsoon season plantings. Vegetation management treatments influenced early growth, survival, and herbivory rates. Physical weed control, which consisted of fibrous weed mats around the base of planted seedlings, showed early advantages over some vegetation management treatments in growth, survival and herbivory deterrence, but all vegetation management treatments had similar survival and herbivory results after 2.5 years. Early survival was poor in all treatments, mainly due to herbivory, which was identified as the principal short-term obstacle to artificial regeneration of ponderosa pine in the Davis Mountains. The larger question regarding feasibility of recovery in this isolated population, particularly if local climatic conditions become increasingly unfavorable, remains.

Generation of alkalic flood rhyolite: Insights from evolution of the Paisano volcano, Davis mountains, Trans-Pecos Texas, U.S.A.

Extensive silicic lava (flood rhyolite) constitutes part of the mid –Tertiary Paisano Volcano shield. This lava, borderline peralkaline quartz trachyte/rhyolite, forms part of a sequence of peralkaline rhyolite – quartz trachyte – trachyte produced as eruptions tapped deeper portions of underlying plutons. Flood rhyolite lava extended as far as 20 km from dikes of the eruptive center of the volcano, creating flows as thick as 100 m.Flood rhyolite was nearly aphyric to sparsely porphyritic, relatively hot (~911 °C) and erupted over a topographically subdued region, forming two lobes that extended north-northeast and southeast from a highland of previously-erupted rhyolite domes. Flood rhyolite extrusion followed eruption of a local ignimbrite, which filled valleys, flattening topography. Successive silicic flows off-lapped each other away from the volcano. Flood rhyolite eruption was followed by a second eruptive sequence that contained coarsely-porphyritic mafic trachyte lava.Silicic lava was most-likely generated by filter pressing from mush zones of mafic plutons. Glomeroporphyritic trachytes of the volcano are mixed rocks, silicic lava incompletely segregated from entrained fragments of mafic plutons. Continued evolution of quartz trachyte/low-silica rhyolite to peralkaline rhyolite was dominated by fractionation of alkali feldspar.

Aridland spring response to mesoscale precipitation: Implications for groundwater-dependent ecosystem sustainability

Aridland springs maintain groundwater-dependent habitats for aquatic and terrestrial species. San Solomon Spring (Texas, USA) is part of a regional karst spring complex in the Chihuahuan Desert that supports several species of federal and state conservation interest. However, drought, climatic variability, and groundwater abstraction threaten discharge and water quality. In the surrounding Delaware Basin, expansion in unconventional oil and gas development using hydraulic fracturing may increase demands on aquifers that also provide flows to the springs. A critical knowledge gap limiting habitat conservation and sustainable groundwater abstraction is that the flow system is not well understood. While the source of most spring discharge is from a Pleistocene-recharged regional flow system, evidence suggests that a modern local flow component provides fresh water influx. However, the exact sources, mechanisms, and timing of localized recharge are unknown. To address these questions, this study combined long-term in-situ spring water quality monitoring (specific conductance, turbidity, and temperature) data with weather station-corrected 4 km gridded precipitation data to quantify the lag response at San Solomon Springs to mesoscale storm events and to delineate potential local recharge zones. Between April 2011 and March 2012, 26 event-flow responses were documented, with an average lag of 43 days between storm event and spring response. Response time varied depending on storm magnitude, spatial extent, and antecedent soil moisture conditions. Cross-correlation analysis of spatially distributed precipitation indicated zones of potential local recharge in the mountain block/mountain front zones and alluvial channels issuing from the Davis Mountains. Some local flow paths appear to cross known watershed boundaries, suggesting that groundwater abstraction in sensitive capture zones should be managed carefully to maintain spring flows and conserve habitats.

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

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.

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.

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.

Basement control of alkalic flood rhyolite magmatism of the Davis Mountains volcanic field, Trans-Pecos Texas, U.S.A.

Voluminous silicic lava flows, erupted ~37.4Ma from widespread centers within the Davis Mountains Volcanic Field (DMVF), covered approximately 10,000km2 with an initial volume as great as 1000km3. Lava flows form three major stratigraphic units: the Star Mountain Rhyolite (minimum 220km3) of the eastern Davis Mountains and adjacent Barilla Mountains, the Crossen Formation (~75km3) of the southern Davis Mountains, and the Bracks Rhyolite (~75km3) of the Rim Rock region west of the Davis Mountains proper. Similar extensive rhyolite lava also occurs in slightly younger units (Adobe Canyon Rhyolite, ~125km3, 37.1Ma), Sheep Pasture Formation (~125km3, ~36Ma) and, less voluminously, in the Paisano central volcano (~36.9Ma) and younger units in the Davis Mountains. Individual lava flows from these units formed fields as extensive as 55km and 300-m-thick.Flood rhyolite lavas of the Davis Mountains are marginally peralkaline quartz trachyte to low-silica rhyolite. Phenocrysts include alkali feldspar, clinopyroxene, FeTi oxides, and apatite, and, rarely, fayalite, as well as zircon in less peralkaline units. Many Star Mountain flows may be assigned to one of four geochemical groupings. Temperatures were moderately high, ranging from ~911 to 860°C in quartz trachyte and low silica rhyolite. We suggest that flood rhyolite magma evolved from trachyte magma by filter pressing processes, and trachyte from mafic magma in deeper seated plutons.The Davis Mountains segment of Trans-Pecos Texas overlies Grenville basement and is separated from the older Southern Granite and Rhyolite Province to the north by the Grenville Front, and from the younger Coahuila terrane to the south by the Ouachita Front. We suggest that basement structure strongly influenced the timing and nature of Trans-Pecos magmatism, probably in varying degrees of impeding the ascent of mantle-derived mafic magmas, which were produced by upwelling of asthenospheric mantle above the foundered Farallon slab. Basalt was able to penetrate Coahuila crust in the Big Bend region. Thicker Grenville crust under the Davis Mountains retarded ascent of mafic magmas, allowing mafic plutons to differentiate into silicic magma that was eventually erupted as flood lava. North of the Grenville Front, magmatism was further delayed and thicker, older crust there may have helped concentrate magmatism under the Davis Mountain region. Only after the onset of Basin and Range faulting was true basalt erupted over much of the Trans Pecos.

Reconstruction of Pinon-Juniper Forest Structure to Examine Historic Wildlife Habitat Characteristics in the Davis Mountains, USA

Changes in pinon-juniper (Pinus spp., Juniperusspp.) communities across the southwestern United States have often decreased ecological diversity of the understory and increases of exotic species. Reconstructing age and establishment patterns provides essential understanding to guide treatments and management for anthropogenically-altered forests. The goal of this study was to determine how patterns of pinon and juniper growth in the Davis Mountains, Texas, varied over time and how this pattern influenced wildlife habitat of several indicator species. Establishment patterns and basal area growth progression were identified, canopy cover estimates regressed from pre-developed canopy regression equations to re-construct historic forest stand structure and canopy characteristics in twenty-year intervals and applied to known wildlife habitat requirements of Montezuma quail (Cyrtonyx montezumae), black bear (Ursus americanus) and White-tailed deer/Mule deer (Odocoileus virginianus/O. hemionus). The sites provided habitat for these wildlife species, but the specific habitat provided changed over time. Prescribed burning could promote better forage for black bear while fire exclusion could improve dense cover for escape and denning cover. Montezuma quail would use thinner, less-dense habitats for forage, loafing and escape cover and the denser stand dynamics for cover and shelter. If forage habitat for Montezuma quail is required, the more open habitats found in the early 1900’s could be re-established by prescribed burning and tree removal. Habitat for White-tailed deer transitioned from more open forage, loafing, fawning cover in the early 1900’s to denser thermal, and escape cover in the later 1900’s. Mule deer habitat transitioned from a preferred open habitat to a more dense cover habitat that would be utilized primarily for bedding. Prescribed burning and tree removal to open up the current habitat would benefit Mule deer and white-tailed deer to a lesser degree.

Spatial Ecology and Habitat Selection of Montezuma Quail in Texas

Montezuma quail (Cyrtonyx montezumae) occur throughout desert mountain ranges in the southwestern United States and northern Mexico. Considered a popular game bird in Arizona and New Mexico, they are not hunted in Texas. A hunting season was proposed for the species in 1997 but met with strong objections, most citing the dearth of information about the species. Much of the literature on Montezuma quail ecology is anecdotal or outdated. Previous researchers had problems capturing birds for marking and, once captured, keeping radio-marked birds alive. We used trained pointing dogs and conducted a radiotelemetry study on Montezuma quail in the Davis Mountains of Texas from January 2009 through September 2010. We captured 72 birds and recorded 966 locations. Home ranges were calculated for 13 individuals which had at least 25 locations. A 95% fixed kernel was calculated on each individual giving a mean 6 SD home range of 2,149.4 6 4,736.8 ha. Movements varied widely by individuals and the greatest straight-line movement was 12.7 km. We also performed habitat selection analysis. Mountain savannah ecological sites were preferred across all 3 spatial scales. Our results confirm that home range size and movements by Montezuma quail occur at a much larger scale than previously reported. Thus, managing lands on a larger scale and targeting mountain savannah ecological sites should be considered.

Fate and Survival of Radio-marked Montezuma Quail

Montezuma quail (Cyrtonyx montezumae) represent one of the least studied North American quail species, particularly in Texas. This lack of information may be partly due to their secretive nature and difficulty of capturing. We provide the first published report of fate of radio-marked Montezuma quail in Texas. We captured, radio-marked, and released 14 Montezuma quail on Elephant Mountain (n = 9) and Davis Mountain Preserve (n = 5) during 2000-2005. We used 2 methods of attachment for pendant style neck-loop radio transmitters. Body-loop transmitters were affixed to quail captured at the Davis Mountain Preserve whereas both body-loop and neck-loop were used at Elephant Mountain. All radio-marked Montezuma quail died within a relatively short period (1-16 days). Causes of mortality for most Montezuma quail were attributed to raptors (n = 9), mammals (n = 1), and miscellaneous (n = 4). Because this low survival rate would not sustain a natural population, we suspect trapping, handling, and/or radio-marking negatively affected survival. It is possible that transmitters potentially restricted escape movements or interfered with other behavior thereby making Montezuma quail more vulnerable to predation. Traditional techniques used to affix radio transmitters or transmitter design itself need to be refined if Montezuma quail are to be studied using radio telemetry.

Post-fire resprouting oaks (genus: Quercus) exhibit plasticity in xylem vulnerability to drought

Resprouting is a key functional trait for species in disturbance prone environments. In many semi-arid environments, woody plants face both fire and drought as recurring disturbances. Past work has demonstrated that oaks inhabiting sky-island forests of the northern Sierra Madre Oriental have differing microhabitat preferences and heavy stem dieback occured during the historic 2011 drought indicating potential xylem failure. These oak species, representing two sections within the genus, are all post-fire resprouters: they can resprout from underground storage organs when fire kills above ground tissue. Resprouts provide an opportunity to examine how functional traits may change as plastic responses to changing environmental conditions. Post-fire resprouts have increased root:shoot ratios relative to adults and therefore have access to more water relative to leaf demand. We expected that if resprouts exhibit plasticity in xylem function, they should favor water transport efficiency over safety: they should have higher maximum xylem conductivity, but greater susceptibility to drought-induced cavitation. We examined four oak species common in the Davis Mountains in west Texas and compared adult physiology with that of resprouts following wildfire. We found that species differed in degree of desiccation avoidance (isohydry) consistent with microhabitat preferences and that the species that were most desiccation tolerant as adults had resprouts significantly more susceptible to xylem cavitation. We found no evidence for a trade-off between efficiency and safety, however.

Assessing habitat relationships of mountain lions and their prey in the Davis Mountains, Texas

Availability and habitat use are central factors in the selection of prey by mountain lions (Puma concolor), and they are important for understanding predator-prey dynamics. We used an array of camera traps to evaluate the relative abundance and spatial distribution of mountain lions and their prey in the Davis Mountains of Texas. Resource selection was evaluated for four criteria: elevation, ecological system, fine-scale terrain ruggedness, and broad-scale terrain ruggedness. We used v 2 analysis to determine whether habitat was used in proportion to availability, and then we calculated a selection index with 95% confidence intervals using a Bonferroni adjustment. We found feral hog (Sus scrofa) to be the most abundant species, composing 23% of the total animals observed. Feral hog and gray fox (Urocyon cinereoargenteus) were the most widespread species, each observed at 33 of 38 camera locations. For each prey species evaluated, habitat use differed significantly from availability for at least one of the four resource criteria. Mountain lion use of resource criteria was not different from availability, except they avoided the second lowest class of broad-scale terrain ruggedness. With knowledge of mountain lion habitat use and the availability of prey, resource managers can better assess what effects mountain lion predation may have on a specific species, thereby allowing for better management of those species.

Forest wildfire and grassland prescribed fire effects on soil biogeochemical processes and microbial communities: Two case studies in the semi-arid Southwest

Fire is a natural disturbance that shapes many ecosystems. In semi-arid regions, where high temperatures and low soil moisture limit nutrient cycling and plant growth, fire is critical to supply nutrients and drive vegetation composition. We examined soil chemical and biological properties to assess the short-term impacts of wildfire and prescribed fires on soil functioning in semi-arid regions of Texas. Better understanding of soil organic matter transformation and nutrient cycling processes will aid land managers in predicting ecosystem recovery response post-fire. Soil samples were collected following both prescribed grassland fires in June of 2009 in Lubbock, TX and the April 2012 Livermore Ranch Complex Fire located in the Davis Mountains, TX. Prescribed fire samples (0–2.5cm) were collected within six h prior to burning and again at 0.5, 24, 48, and 168h post-fire to experimentally examine short-term influences of fire and fire frequency (1× vs. 2×) on soil carbon dynamics, inorganic nitrogen, and microbial community composition. Wildfire samples (0–5cm) were collected two and six months following the wildfire. We evaluated the effects of three burn severity levels and sampled under three tree species (Juniperus deppeana, Pinus cembroides, and Quercus grisea). Within 0.5h of the prescribed fire, CO2 flux, NH4+-N concentration and total microbial biomass (as estimated by total fatty acid methyl esters) increased. A shift in the microbial community from a predominance of fungi to Gram positive bacteria occurred immediately following the fire. Chemical shifts were short lived (decreased within 24h), but the biotic shift to a dominance of Gram negative bacteria and actinomycetes was measured in samples collected after 168h. Soil pH and NH4+-N concentration increased at two and six months following the wildfire. In contrast, soil organic matter content decreased at two months post wildfire which, in combination of abiotic conditions such as low moisture content (<3.3%), resulted in reduced soil microbial biomass and enzyme activity. Increased soil moisture six months post fire created more favorable conditions for nitrification resulting in increased NO3−-N concentration (0.8 to 36.1mgNO3−-Nkg−1soil), particularly following high severity fire. Prescribed fire did not have lasting impacts on soil nutrients, but both prescribed and wildfire resulted in increased NH4+-N, shifts in microbial community structure and decreased in microbial biomass. While the increase in nitrogen maybe be beneficial to the plant growth and revegetation, the loss of microbial biomass may have far reaching implications to the overall sustainability of the soils in these systems.

First record of the genus Leptanilloides (Hymenoptera: Formicidae: Dorylinae) from the United States.

We describe a new species of the Neotropical genus Leptanilloides, L. chihuahuaensis sp. n., based on male specimens from the Davis Mountains in western Texas. Known males of species of Leptanilloides are compared with L. chihuahuaensis. This is the first report of the genus from the United States and the Nearctic region. Previously, the Leptanilloides genus-group was only known to occur from southern Mexico to southeastern Brazil; and thus, this record from Texas represents a remarkable extension of the known range of the genus.

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

Populus tremuloides (quaking aspen) is found from the Pacific to the Atlantic Ocean in the northern United States and Canada, and at higher elevations in the western United States and northern Mexico. While P. tremuloides can reproduce sexually or asexually, it is primarily a clonal species in the intermountain west, reproducing vegetatively via root sprouts, yielding genetically identical stems or ramets. In west Texas, isolated, outlier stands occur in the Guadalupe, Davis, and Chisos Mountains at an elevation of approximately 2300 m. This study utilized seven microsatellites or simple sequence repeats (SSRs) to examine leaf samples from 10 widely separated stems in 10 isolated P. tremuloides individual stands within the Davis Mountains to determine the level of clonal and genetic diversity. We then examined differentiation among stands. Each stem sampled within a stand was genetically identical to all stems examined in that stand or was part of a clone. There were eight genetically identical clones from these ten stands, with three stands being genetically identical or part of the same clone. Many of the genotypes shared several of the same alleles and the remaining alleles were only a few base pairs apart. Some of these alleles have been previously identified in other western North American P. tremuloides stands. Microsatellites identified several triploid patterns consistent with possible aneuploidy, which is concurrent with previous studies.