Desert Mountain Research Articles

Evaluation of the Digital Opacity Compliance System in High Mountain Desert Environments

The digital opacity compliance system (DOCS) has been proposed as an alternative to the U.S. Environmental Protection Agency Reference Method 9 (Visual Determination of the Opacity of Emissions for Stationary Sources). The DOCS, which employs standard digital photography to estimate the opacity of visible emissions, was evaluated in a high mountain desert environment located in Weber County, UT. The DOCS recorded an average opacity deviation of 5.28% when applied to black smoke plumes having true opacities in the range of 0–100%, an error rate that was found to be significantly less than 7.5% (allowable error rate for attaining certification under Method 9). In contrast, results from estimating the opacity of white smoke plumes indicated that the accuracy of the DOCS was less than the Method 9 error rate only in the opacity range of 0–60%, over which the DOCS average opacity deviation was determined to be 6.7%. For the 0–40% opacity range, the DOCS recorded an average opacity deviation of 5.44% and 5.9% for black and white plumes, respectively. Results from the present study suggest that the DOCS has the potential to quantify visible opacity with an error rate that is significantly less than the Method 9 permissible error rate. Although encouraging, it is unclear to what extent the DOCS is affected by climatic conditions other than those encountered in a dry desert environment. Future studies should focus on evaluating the performance of the DOCS under variable weather conditions.

Grinding Gears on the Roads that Ruin

Automobiles and wilderness may not always make good bedfellows, but both have long served as key symbols of freedom and independence. At times, the protean nature of what they symbolize can lead to a powerful congruence of meaning-as in the iconography of an SUV advertisement that places a shiny new vehicle in the heart of a vast expanse of mountainous desert. On the other hand, wilderness is also defined by the complete absence of motorized vehicles. In this respect, cars and wilderness represent an essential conflict between the freedom to do as one wishes and the freedom to avoid the wishes

Vegetation Patterns as Affected by Aspect and Elevation in Small Desert Mountains

Studies of vegetation patterns on small desert mountains have rarely been conduct- ed. The purpose of this study was to evaluate the influence of aspect and elevation on vegetation of Mt. Summerford, a small desert mountain characteristic of the Basin and Range Province of southwestern United States and northern Mexico. Vegetation was randomly sampled on 4 aspects and 3 elevations (0-80 m, 80-160 m, and 160-240 m) of the mountain. South (S) and west (W) aspects had lower grass cover and higher shrub density than east (E) and north (N) aspects. Grass cover decreased as elevation increased on E and N exposures. In contrast, grass cover increased as elevation increased on S and W exposures. A high density of succulent species was found on lower elevations of the S and W aspects. The most frequent species on the mountain were Bouteloua curtipendula, Bouteloua eriopoda, Muhlenbergia porteri, Aristida ternipes, Aloysia wrightii, Ericameria lari- cifolia, Gutierrezia sarothrae, Fouquieria splendens, Dasylirion wheeleri, and Opuntia. Composition of these species, as a mosaic unit, was significantly different among the aspect-elevation units. Species richness was higher in S and W than in E and N aspects. Differences in vegetation patterns were attributed to differential water and nutrient availability on aspects and elevations. This study sug- gests that topographical change is responsible for vegetation patterns in mountains less than 500 m high.

Properties of soil pockets on arid Nama Karoo inselbergs–the effect of geology and derived landforms

Soil pockets in desert mountain habitats are extremely important, as they offer a foothold for seedlings, usually have more plant available water and thus provide a favourable habitat for plant growth in an arid surrounding. This study investigated properties of soil pockets of isolated arid mountains (i.e. inselbergs), asking the following questions:•Does the underlying geology influence soil properties and if so, in what way?•What is the effect of topography, i.e. position on slope and landform?•Does slope aspect influence soil properties?Soil samples from four arid study areas in Namibia along a north–south gradient, each comprising a set of inselbergs, were analysed and tested for differences in geology, habitat (representing a topographic gradient) and slope aspect.This study showed that on arid inselbergs:•physical soil properties were determined by the underlying geology,•chemical soil properties were influenced by the underlying geology and likely biogenic processes as well as atmospheric input,•soil properties were affected by topography and landform, but•soil properties were not influenced by slope aspect.The role of inselbergs contributing nutrients to surrounding lowlands may be critical to maintain functioning ecosystems and landscapes. Inselbergs could thus serve as sources of nutrients as well as seeds, an important aspect to be considered in conservation and resource planning.

Prehistory of the Carson Desert and Stillwater Mountains: Environment, Mobility, and Subsistence in a Great Basin Wetland, by Robert L. Kelly, University of Utah Anthropological Papers Number 123, Salt Lake City, 2001

The Great Basin of Western North America is one of the. legendary deserts of the world. This rugged, wide open, and apparently harsh landscape has long served as a backdrop for human drama. Gold seekers and immigrants of the 19th century immortalized the rigors of travelling across the Great Basin on their way to greener grass in California and Oregon. But archaeological research has shown that human occupation of the Great Basin dates back for thousands of years, and ethnographic accounts of Native Americans who lived in this desert have played an important role in the development of concepts of hunter-gatherer subsistence and settlement patterns. It is the Indians of the Great Basin that Julian Steward (1938) studied for his well-known model of sodo-political organiza­tion and evolution (Steward 1955; also see Service 1975), Jesse Jennings (1957) later used Steward's model in his development of the Desert Culture concept, which was widely adapted to other North America deserts.

Gold dispersion in Andean desert environments (Atacama, Chile)

The mechanism of Au dispersion in sediments of mountainous desert environments has been studied in two different areas of the Chilean Andes. The San Pedro de Cachiyuyo placer (ca. 1800 m a.s.l.) consists of alluvial fans and ephemeral stream sediments deposited in a stable piedmont. The primary Au source is Cu–Au-bearing hydrothermal tourmaline breccia. The relief of this area is low (1850 m) and the average annual rainfall is ca. 20 mm. The La Coipa area (ca. 4000 m a.s.l.) is characterized by a rugged relief. The annual average rainfall is ca. 100 mm. The sedimentary deposits are less sorted than in San Pedro de Cachiyuyo and consist of ephemeral stream alluvium and slope deposits formed in a periglacial environment. The primary Au sources are two volcanic-hosted epithermal precious metal deposits. At San Pedro de Cachiyuyo, the halo is less than 1 km in length and the highest Au concentration are observed at the break in slope between the hillside and the piedmont. In the La Coipa area, Au was only detected by chemical analysis in the 125–63 μm and <63 μm fraction; however, the dispersion halo extends for over 10 km from the source. In both cases the geochemical signal of gold was strongest in the fraction <63 μm.

96/04256 The habitat of two deserts in India: hot-dry desert of Jaisalmer (Rajasthan) and the cold-dry high altitude mountainous desert of Leh (Ladakh)

96/04256 The habitat of two deserts in India: hot-dry desert of Jaisalmer (Rajasthan) and the cold-dry high altitude mountainous desert of Leh (Ladakh)

The habitat of two deserts in India: hot-dry desert of Jaisalmer (Rajasthan) and the cold-dry high altitude mountainous desert of Leh (Ladakh)

This paper explores the possibility of developing a design methodology and criteria for climatically responsive buildings and settlements for the two desert conditions of India, i.e. hot-dry desert of Jaisalmer (Rajasthan) and cold-dry desert of Leh (Ladakh), through a study of the indigenous architecture of these areas. The method explained, in detail, in the paper is based essentially on development of a mathematical model after co-relation of the monitored thermal performance and computer simulation of indifenous buildings. This paper limits its presentation to the stage of thermal performance data and analysis.

Bootlegging on a desert mountain: The political ecology of Agave (Agave spp.) demographic change in the Sonora river valley, Sonora, Mexico

Recent studies suggest that wild agave (Agavespp.) plants in Sonora, Mexico, are being over-harvested by mescal makers on communal lands. Using the conceptual framework of regional political ecology (Blaikie and Brookfield, 1987), I discuss the ecological processes of agave depletion, and investigate the social, economic, and political contexts in which unsustainable harvest practices arise. Whereas all the mescal makers have knowledge of sustainable harvest methods, population growth, expansion of agriculture onto ecologically marginal lands, and increasing dependence on wild harvested products from communal lands created the socioeconomic context for increased demand for mescal income. The ideology of household autonomy, and the belief that the village has no right to internally regulate use of the commons, created the political context for rapid, unsustainable harvesting—a tragedy of the commons. However, recent cultural changes have caused a reversal of this trend, and some wild agave populations may be recovering.

A Proposed Standard Fog Collector for Use in High-Elevation Regions

Abstract The collection of fog droplets by vegetation is an important wet deposition process. It can, in fact, dominate the chemical and hydrological input to certain high elevation watersheds. However, measurements of fog deposition are rarely made and, where they do exist, comparisons of deposition rates in different locations have been hampered by the use of innumerable types of collection devices. A simple, inexpensive, 1-m2 fog collector that can produce measurements of the deposition of fog water to a vertical surface is described here. The collector has been used successfully in five countries to investigate the variation of fog deposition in complex terrain and to estimate the deposition to trees and to much larger fog collectors. It is proposed that it be employed widely as a standard to quantify the importance of fog deposition to forested high elevation areas and to measure the potential collection rates in denuded or desert mountain ranges. The standard fog collector costs about the same as a ...

Rumen Characteristics of Desert Races of Mountain Sheep and Desert Mule deer

use of forage classes. Diets range from consisting primarily of graminoids (Barrett, 1964; Dominguez, 1976) to those dominated by browse and forbs (Krausman et al., 1989). The digestive anatomy plays a critical role in establishing constraints on herbivore diet composition (Hanley, 1982) and is an important determinant of ecological niche (Bell, 1971; Janis, 1976). Ruminoreticular (RR) volume relative to body size is considered important in relation to the ability to digest graminoid species in other than succulent condition (Hanley, 1982). Within ruminants, species that selectively feed primarily on forbs and succulent vegetation tend to have smaller digestive capacities than roughage grazers (Hofmann, 1973). Graminoid species contain considerable amounts of cellulose as a structural

Biotope and distribution of Blanford's fox

Blanford's fox Vulpes cana has been considered as one of the rarest mammals in south-west Asia. Recently it has been discovered in several locations in the Middle East. The authors conducted a survey of Blanford's foxes in the mountainous desert regions of Israel and found that they are common in Israel, but restricted to a specific habitat. Additional surveys in other Middle Eastern countries are essential for the conservation of this species.

Seasonality of natural transmission of bovine anaplasmosis under desert mountain range conditions

Summary Splenectomized cattle and mature, splee-nintact cattle were used as sentinels in a 4-year study to assess the seasonality of naturally transmitted anaplasmosis. Sentinels were exchanged and/or monitored monthly on 4 study areas of desert mountain range land in Idaho, Oregon, and Utah. Acute Anaplasma infections were diagnosed in sentinels every month of the year. Of 44 total infections, 29 (66%) were detected during March through August, the primary arthropod season. From December through February, 8 (18%) of the total 44 Anaplasma infections were diagnosed; the winter tick, Dermacentor albipictus, was the probable disease vector. Susceptible cattle were determined to be at risk throughout the year, and anaplasmosis should be considered as a possible diagnosis in cattle with anemia during any season.

Hydrologic characteristics of a small desert mountain stream: implications for short-term magnitude and frequency of bedload transport

This paper examines the magnitude and frequency of fluvial processes over a 24-year period for a small desert mountain stream in southern Arizona. The hydrologic data indicate that flow occurred in this channel only 0·05% of the time. The probability density function of flow is distinctly non-lognormal and approximates a one-parameter gamma distribution due to the lack of base flow. Estimation of bedload transport for the flows indicates that the effective discharge for transport is probably equalled or exceeded only about 0·01% of the time, but may have a recurrence interval of approximately 2·5 years. A close correspondence between estimated bankfull flow of the active channel and the effective discharge suggests that equilibrium between form and process occurs in this system. However, because the active channel lies within an arroyo, other factors, such as catastrophic floods, appear to shape the gross channel morphology, which is in disequilibrium with the short-term hydrologic regime.

Mutual Adjustments between Process and Form in a Desert Mountain Fluvial System

Abstract The analysis of earth surface systems is complicated by mutual adjustments among geomorphic variables. Most statistical models used by geomorphologists implicitly assume unidirectional causation. Simultaneous-equation models represent an alternative statistical approach by which mutual adjustment mechanisms can be analyzed explicitly. This technique is used to develop a process-response model of a small desert mountain fluvial system in order to examine the system's internal structure and dynamics. In general, results confirm the expected interactions among variables in the model. Discharge, size of bed material, and the type of bank material are the dominant factors directly influencing channel width, suggesting that channel form reflects an interaction among hydrologic conditions, the caliber of the sediment load, and the resistance imposed by the channel perimeter. Results also indicate that local and upstream energy conditions strongly influence the mean grain size and sorting of the streambe...

The Pragmatics of Observation

My eyes are notoriously bad, so I am not sure whether I have ever seen a meteor. Others have seen them, of course, but it is important to me to observe them first hand. I even go to the trouble to hike at night in the desert mountains so that viewing conditions will be ideal. I scan the sky through my thick glasses, but to no avail. My companions have sighted several, the latest just to the left of that peak. And still I am unsure. Did I really see the meteor, or was it just that my eye twitched? I suspect that this question has no unambiguous answer and that understanding why it lacks such an answer will provide important clues about the role of observation in scientific theorizing.

Flood hazard assessment for land-use planning near desert mountains

Metropolitan areas located in arid and semiarid environments are rapidly expanding onto the piedmonts of nearby desert mountains. Hazards to urban development are posed by the complex fluvial systems that characterize these environments, yet no generally accepted methodology exists for evaluating flood hazards on desert piedmonts. An approach to flood hazard assessment is presented that involves the hydrogeomorphic analysis of land surfaces. Five flood hazard zones are identified for an area in central Arizona by analyzing the spatial variation of landforms and their associated fluvial processes. The methodology is applicable to similar environments elsewhere because it is based on the identification of forms and processes common to arid regions. The information provided by the analysis can form the basis for a comprehensive flood hazard management plan.

Influence of Weather and Density on Lamb Survival of Desert Mountain Sheep

This report concerns the effect of weather on lamb survival in desert mountain sheep (Ovis canadensis nelsoni) to 6-8 months of age in the River Mountains, Nevada, and how it integrates with density to limit the population. Regression analyses were used to examine relationships between lamb survival and weather variables from 1970 to 1982. Autumn precipitation (Sep-Dec) of the preceding year (during gestation) had a significant (P < 0.05), positive effect on lamb survival. Herd density was significantly (P < 0.05) and inversely related to lamb survival. Spring winds had a positive and significant (P < 0.05) effect on lamb survival. Multiple regression revealed that 87% of the variability in lamb survival was accounted for by autumn precipitation during gestation (52%) and sheep density (35%).

Vocalizations of the Purple Martin

Ten types of vocalizations of Purple Martins (Progne subis) from Texas and Arizona were described and compared. Solitary-nesting martins in Arizona did not possess greater vocal repertoire sizes than martins nesting colonially in Texas, which suggests that vocal repertoires are not evolutionarily plastic and have not changed with recent shifts toward coloniality in Texas birds. Some vocalizations differed markedly in structure between these populations, documenting for the first time, geographical vocal variation in the Hirundinidae. A re-examination of subspecific affinities of Purple Martins in Arizona seems warranted on the basis of voice; birds in mountain forests have vocalizations similar to those of birds in deserts, and both differ from the eastern nominate race. Purple Martins possess a greater vocal repertoire than do more colonial swallows, probably because historically they have been largely solitary and lacked acoustical constraints on the evolution of vocal repertoires. The Purple Martin (Progne subis) is a widespread North American swallow, nesting in backyard birdhouses in the eastern parts of its range and in remote high mountain forests and deserts in the West. Its breeding biology and behavior have received considerable research attention (Allen and Nice 1952; Johnston and Hardy 1962; Finlay 1971; Niles 1972; Brown 1978a, b, 1979, 1980; Brown and Bitterbaum 1980), but, aside from brief comments by Johnston and Hardy (1962), its vocalizations have not been described. This study was undertaken with three objectives. First, I sought to test the hypothesis (Brown 1983, in press) that solitary swallows have larger vocal repertoires than colonial species. Purple Martins, at least before the recent advent of birdhouses, were largely solitary, nesting primarily in abandoned woodpecker holes. Following Brown (1983, in press), one might expect larger vocal repertoires in martins than in more colonial species such as the Cliff (Hirundo pyrrhonota) or Bank (Riparia riparia) swallows. This study examined repertoire size in martins. Second, I examined whether either call structure or repertoire size differ among populations of Purple Martins inhabiting different geographical regions and exposed to different selective pressures. Martins nesting in suburban backyards in Texas, often in colonies of up to 50 pairs, were compared with birds nesting solitarily in mountain forests of Arizona. If martins in Arizona have larger vocal repertoires than those in Texas, this could mean that vocal repertoire size is evolutionarily plastic, possibly having changed with the recent shift toward coloniality in Texas birdhouse populations. Differing social structures could be very important in the evolution of geographical variation in avian vocalizations. Lastly, I wished to catalog and describe vocalizations for a genus about whose vocal communications nothing had been reported. STUDY SITES, METHODS, AND TERMINOLOGY I conducted this study in Sherman, Grayson County, north central Texas, and in the Chiricahua Mountains, Cochise County, southeastern Arizona. In Texas, most work was done from 1970 to 1979 at one colony (elevation 238 m) consisting of up to seven birdhouses (see Brown 1979, 1980 for details on study areas and how individual martins were recognized), with all actual recording done 5-22 April 1980 and 11-22 July 1980. In Arizona, martins were studied in 1980 at nesting sites in woodpecker holes of dead snags at Rustler Park (elevation 2,545 m) and near Herb Martyr Lake (elevation 1,924 m), both in the Chiricahuas, with all actual recording done 11-24 June. Field recordings were made with Uher 4000 Report L and 4000 Report 1C tape recorders and Uher M517 and Electrovoice Soundspot microphones, the former mounted in a 60-cm parabolic reflector. Tape speeds were 19 and 9.5 cps. Sonograms were made on a Kay Elemetrics Sona-Graph Model 6061-B using wide band pass setting and linear scale. Following Thorpe (1961) and Brown (in press), I used the following bioacoustical definitions: figure, a continuous tracing on a sonogram; syllable, any single figure or any two figures lasting 50 msec or less; song, a series of sounds of more than one type, uttered in succession and forming a recognizable sequence or pattern in time; subsong, an irregular and ill-defined series of syllables of lower in-

Observations on Adult Bionomics and Larval Ecology of Leptoconops Torrens (Diptera: Ceratopogonidae) During an Outbreak in the Coachella Valley of Southern California, USA

Following a heavy thunderstorm in the desert mountains of southern California, an outbreak of the hematophagous midge Leptoconops torrens was observed in Magnesia Spring Canyon, near the city of Rancho Mirage, in June 1981. Studies were undertaken to examine the reproductive bionomics of the adults and to locate the larval habitat. Preliminary observations suggested that host-seeking females descended from the foothills via the canyon into the wash at Rancho Mirage. This population was characterized by apparently synchronous emergence, high attack rates by nulliparous females, and a precipitous decline in activity within a few days of peak abundance. Attack activity was diurnally bimodal, peaking 2–4 h after sunrise and again at sunset. Few females survived to initiate a 2nd gonotrophic cycle; consequently, little vector potential existed. Mating swarms were observed 3.2 km into the canyon (450 m above sea level) at 1430 h in bright sunlight with air temperature at 43.3 °C. Nearby, a few larvae were found in the damp sand and moss in areas of the canyon floor protected from the floods that accompany heavy rainfall; however, the primary larval habitat may be in the numerous cracks and crevices of the rocky terrain. The inaccessibility of these areas precludes larval suppression. Certain peculiarities in the bionomics of L. torrens are discussed in terms of adaptation to the harsh desert environment.