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The recognition and characterization of aeolian dust in soil contribute to a better understanding of landscape and ecosystem dynamics of drylands. Results of this study show that recently deposited dust, sampled in isolated, mostly high-ground settings, is chemically and mineralogically similar on varied geologic substrates over a large area (15 000 km2) in the Mojave Desert. The silt-plus-clay fraction (fines) on these isolated surfaces is closely alike in magnetic-mineral composition, in contrast to greatly dissimilar magnetic compositions of rock surfaces of vastly different lithologies, on which the fines have accumulated. The fines, thus, are predominantly deposited dust. The amounts of potential nutrients...
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Natural landscapes in the Southwestern United States are changing. In recent decades, rising temperatures and drought have led to drier conditions, contributed to large-scale ecological impacts, and affected many plant and animal species across the region. The current and future trajectory of climate change underscores the need for managers and conservation professionals to understand the impacts of these patterns on natural resources. In this regional assessment of the Southwest Climate Change Initiative, we evaluate changes in annual average temperatures from 1951–2006 across major habitats and large watersheds and compare these changes to the number of species of conservation concern that are found within these...
The recognition and characterization of aeolian dust in soil contribute to a better understanding of landscape and ecosystem dynamics of drylands. Results of this study show that recently deposited dust, sampled in isolated, mostly high-ground settings, is chemically and mineralogically similar on varied geologic substrates over a large area (15 000 km2) in the Mojave Desert. The silt-plus-clay fraction (fines) on these isolated surfaces is closely alike in magnetic-mineral composition, in contrast to greatly dissimilar magnetic compositions of rock surfaces of vastly different lithologies, on which the fines have accumulated. The fines, thus, are predominantly deposited dust. The amounts of potential nutrients...
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Studies were conducted in the central Mojave Desert to quantify how creosote bushes (Larrea tridentata) respond to physical damage during large-scale military training exercises. Creosote bush possesses a resilient growth form that recovers from repeated physical damage via resprouts arising from meristems in stem bark below severed or crushed canopy units. At high levels of disturbance by heavy vehicles, nearly all individuals showed measurable breakage, but without additional damage each plant can regain a full canopy within 5 years under arid field conditions. Resprouts exhibited more vigorous growth and doubled the biomass accumulation stimulated by high rainfall of 1998, an El Niño year, vs. a normal year....
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In this observational pilot study, we worked at the largest existing solar tower facility in the world (Ivanpah Solar Electric Generating System - ISEGS) to assess the efficacy of using radar, surveillance video, and insect trapping to monitor animals flying near the towers. During week-long site visits in May and September, we monitored the airspace surrounding towers and observed insects, occasional birds, and bats under a variety of environmental and operational conditions. This dataset enumerates invertebrates captured using both malaise and funnel traps placed on the ground in the immediate vicinity of solar towers in the locations shown in Figure 2 of the associated paper. The locational information below...
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In this observational pilot study, we worked at the largest existing solar tower facility in the world (Ivanpah Solar Electric Generating System - ISEGS) to assess the efficacy of using radar, surveillance video, and insect trapping to monitor animals flying near the towers. During week-long site visits in May and September, we monitored the airspace surrounding towers and observed insects, occasional birds, and bats under a variety of environmental and operational conditions. This dataset consists of raster portable network graphics (png) images of the planned position indicator (ppi) display from a Furuno FR2127 portable radar unit to a maximum range of 1.5 km. A new image is written with each rotation of the...
Precipitation varied substantially in the Mojave Desert through the 20th century in a manner broadly similar to the other warm North American deserts. Episodes of drought and prolonged dry conditions (1893–1904, ca. 1942–1975, and 1999-present) alternated with relatively wet periods (1905–ca. 1941 and ca. 1976–1998), probably because of global-scale climate fluctuations. These are the El Niño-Southern Oscillation that affects interannual climate and the Pacific Decadal Oscillation that evidently causes decadal-scale variability such as prolonged dry and wet episodes. Studies done in the late 20th century demonstrate that precipitation fluctuations affected populations of perennial vegetation, annuals, and small...
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In this observational pilot study, we worked at the largest existing solar tower facility in the world (Ivanpah Solar Electric Generating System - ISEGS) to assess the efficacy of using radar, surveillance video, and insect trapping to monitor animals flying near the towers. During week-long site visits in May and September, we monitored the airspace surrounding towers and observed insects, occasional birds, and bats under a variety of environmental and operational conditions. This dataset is comprised of the unedited digital video imagery we gathered during those site visits. There are four types of video imagery included in the data set: (1) "EMCCD camera" is the output of an electron multiplying charge-coupled-device...
Long-lived desert shrubs exhibit infrequent, episodic recruitment from seed. In spite of this long time scale, selection on life history attributes that affect seedling recruitment should be strong. We studied factors affecting germination phenology and seedling establishment for Coleogyne ramosissima, a dominant shrub species in the ecotone between warm and cold deserts in western North America. We also examined ecotypic differentiation in establishment strategy in response to selection regimes in two contrasting habitats. We followed patterns of dormancy loss, germination, emergence, and survival in reciprocal field experiments at warm winter Mojave Desert and cold winter Colorado Plateau study sites. Seed germination...
Desert tortoises, Gopherus agassizii, generally were active in the spring and fall. They often became active during and after infrequent showers and thunderstorms, and drank from temporary pools of standing water even when air temperatures were suboptimal (9-15 C). In several instances tortoises constructed shallow catchment basins which held water for as long as six h. Thus tortoises can obtain drinking water by modifying their environment. Following small amounts of rainfall (5.6 mm) in July 1976, six tortoises increased an average of 9.2% in body weight; this increase was due to ingestion of water. Drinking may be an important source of water for this species. Published in Herpetologica, volume 36, issue 4, on...
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Estimated precipitation data were compiled using the WestMap web site (http://www.cefa.dri.edu/Westmap/) from 1995-2013. We selected pixels on the map shown on their web site that were in the core of our study areas: one near Palm Springs, California and the other at Sugarloaf Mountain in the Tonto National Forest of Arizona. WestMap uses PRISM data to make point measurements of climate data and a digital elevation model of terrain to create estimates of monthly climate elements. Estimates are derived for a 4km grid, for ease in mapping and GIS applications. PRISM is an integrated set of rules, decision making, and calculations designed to imitate the process an expert climatologist would go through when mapping...
The interactions between playa hydrology and playa-surface sediments are important factors that control the type and amount of dust emitted from playas as a result of wind erosion. The production of evaporite minerals during evaporative loss of near-surface ground water results in both the creation and maintenance of several centimeters or more of loose sediment on and near the surfaces of wet playas. Observations that characterize the texture, mineralogic composition and hardness of playa – surfaces at Franklin Lake, Soda Lake and West Cronese Lake playas in the Mojave Desert (California), along with imaging of dust emission using automated digital photography, indicate that these kinds of surface sediment are...
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Data for static groundwater-levels measured in about 645 wells during the period of January-April 2016 by the United States Geological Survey (USGS), the Mojave Water Agency, and other local water districts were compiled to construct a regional water-table map. The downloadable shapefile shows the elevation of the water table in the Mojave River and Morongo groundwater basins. This dataset is a digital representation of the contours presented on Plate 1 of Regional Water Table (2016) in the Mojave River and Morongo Groundwater Basins, Southwestern Mojave Desert, California: U.S. Geological Survey Scientific Investigation Map, doi:10.5066/sim3391, published by Meghan C. Dick and Adam R. Kjos. It is a continuation...
Egg production by desert tortoises was estimated at two sites in San Bernardino, California: Ivanpah Valley in 1980 and 1981 and Goffs in 1983, 1984 and 1985. Mean clutch frequencies were estimated for 1980 (1.60) and 1981 (1.10) from mass changes observed among sexually mature females weighed every 1-2 wk. Mean clutch frequencies in 1983 (1.89), 1984 (1.57) and 1985 (1.75) were estimated from periodic X-rays of females. Clutch sizes were also determined from radiographs. Tortoises at Goffs typically laid 1-2 clutches during May and June, but one female failed to lay eggs in 1984 and single tortoises laid three clutches in 1983 and 1985. If tortoises laid two clutches, the second was faintly visible in X-rays within...
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This raster dataset contains biophysical settings (band 1) and wildfire frequencies (band 2) within the Mojave Desert ecological section of California. Biophysical settings were developed by the LANDFIRE program and fires occurences were mapped by the Monitoring Trends in Burn Severity (MTBS) program.
The desert pocket mouse (Chaetodipus penicillatus) comprises 6 nominate subspecies that occupy warm, sandy desert-scrub habitats across the Mojave and Sonoran deserts. The most thorough morphological assessment within the species noted variable levels of distinctiveness, leading to uncertainty regarding the geographic distributions of subspecies. Subsequent genetic assessments using chromosomal, allozymic, and mitochondrial DNA (mtDNA) sequence data detected a general east?west divergence centered on the Colorado River, but few locations were included in these assessments. We investigated phylogeographic structure in C. penicillatus by sequencing regions of mtDNA for 220 individuals from 51 locations representing...
Blackbrush is a dominant shrub species in the transition zone between North American warm and cold deserts. Its seeds are dormant at dispersal and lose dormancy in response to moist chilling. Seeds from warmer low-elevation habitats have shorter chilling requirements and a higher optimum chilling temperature than those from colder habitats where winter snow regularly occurs. This ecotypic variation functions to time germination optimally in habitats with contrasting chilling regimes. Regulation of germination phenology is an important feature of the life history of this ecotonal species, which must be able to migrate elevationally through recruitment from seed in response to long-term climatic shifts in order to...
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The dataset delineates ecological zones within California deserts. We derived ecological zones by reclassifying LANDFIRE vegetation biophysical setting types, plus defined various non-wildland (e.g. developed urban/agriculture/roads) and non-burnable (e.g. open water/barren) areas using LANDFIRE existing vegetation types. The 43 biophysical setting types present within the study area were grouped into 13 general vegetation types, which were further grouped into 4 elevation-based ecological zones plus one riparian zone according to their constituent plant associations.
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​Abstract: Climate change predictions include warming and drying trends, which are expected to be particularly pronounced in the southwestern United States. In this region, grassland dynamics are tightly linked to available moisture, yet it has proven difficult to resolve what aspects of climate drive vegetation change. In part, this is because it is unclear how heterogeneity in soils affects plant responses to climate. Here, we combine climate and soil properties with a mechanistic soil water model to explain temporal fluctuations in perennial grass cover, quantify where and the degree to which incorporating soil water dynamics enhances our ability to understand temporal patterns, and explore the potential consequences...
Categories: Data, Publication; Types: Citation, Map Service, OGC WFS Layer, OGC WMS Layer, OGC WMS Service; Tags: 2012, AZ-02, AZ-03, AZ-04, Academics & scientific researchers, All tags...
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The dataset delineates ecological sections within California deserts. These deserts occupy the southeastern portion of California and include two ecoregional provinces comprised of five desert regions ("ecological sections"; Miles and Goudey 1997). The American Semi-Desert and Desert Province (warm deserts) includes the Mojave Desert, Sonoran Desert, and Colorado Desert sections in the southern 83% of the California desert. The Intermountain Semi-Desert Province (cold deserts) includes the Southeastern Great Basin and Mono sections in the northern 17% of the region.
map background search result map search result map Resprout characteristics of creosote bush (Larrea tridentata) when subjected to repeated vehicle damage Managing Changing Landscapes in the Southwestern United States Invertebrate Data Radar Data Video Files Ecoregion sections of California deserts Biophyiscal settings and wildfire frequencies in the Mojave Desert ecological section of California, 1984 to 2013 Ecological zones of California deserts Desert Tortoise Ecology and Precipitation, Mojave and Sonoran Deserts—Data Regional Water Table (2016) in the Mojave River and Morongo Groundwater Basins, Southwestern Mojave Desert, California Publication and Report: Ecosystem Water Balance in a Desert Grassland Invertebrate Data Video Files Resprout characteristics of creosote bush (Larrea tridentata) when subjected to repeated vehicle damage Desert Tortoise Ecology and Precipitation, Mojave and Sonoran Deserts—Data Regional Water Table (2016) in the Mojave River and Morongo Groundwater Basins, Southwestern Mojave Desert, California Biophyiscal settings and wildfire frequencies in the Mojave Desert ecological section of California, 1984 to 2013 Ecological zones of California deserts Ecoregion sections of California deserts Managing Changing Landscapes in the Southwestern United States Publication and Report: Ecosystem Water Balance in a Desert Grassland