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Natural and anthropogenic changes in basin lake levels in the western U.S. expose saline, alkaline substrates that are commonly colonized by shrubs in the Chenopodiaceae. On a chronosequence of recently exposed substrates at Mono Lake, California, Sarcobatus vermiculatus has greatest biomass accrual, seed production, seedling establishment, and leaf N at younger sites where soils are extremely saline and alkaline. These field observations and an understanding of the role of N-containing compatible solutes in salinity tolerance of halophytes led to our prediction that Na and N interactions stimulate Sarcobatus performance. To test this, we grew Sarcobatus juveniles for 2 years in the greenhouse at 4 levels of NaCl...
Growth rates estimated using the scale annuli of flannelmouth sucker, Catostomus latipinnis, did not differ between fish collected from the Gunnison and Colorado rivers, and the Green and Yampa rivers. However, body condition and fecundity were significantly greater in the former population. Age of first maturity for male and female fish from all rivers was IV; and most fish were mature by age VII. The smallest mature female collected was 405 mm, and the smallest mature male was 391 mm total length. Fecundity ranged from 4,000 ova in fish 450 mm long to 40,000 ova in a 500-mm fish: mean ovum diameter was 2.39 mm. Ripe male flannelmouth suckers were collected from early April through June; ripe females were collected...
Desert plants can influence the pattern of resources in soil resulting in small-scale enriched zones. Although conceptually simple, the shape, size, and orientation of these "resource islands" are difficult to study in detail using conventional sampling regimes. To demonstrate and alternative approach, we sampled soil under and around individual Artemisia tridentata (sagebrush), a dominant shrub of cool desert environments, and analyzed the samples with univariate statistics and geostatistics. Univariate statistics revealed that soil variables like total inorganic-N, soluble-C, and microbial biomass-C were distributed with highest mean values within about 25 cm of the plant axis and significantly lower mean values...
ABSTRACT.-We compared diet of young-or-year Colorado squawfish (Ptychocheilus lucius), an endangered cyprinid, with diets of other fish <75 mm total length (TL) collected from backwaters of the Green River between river kilometers 555 and 35 during summer and autumn 1987. Species included native Rhinichthys osculus, Catostomus discoholus, and C. latipinnis, and nonnative Cyprinella lutrensis, Notrupis stramineus, Pit"l1&'Phales promelas, Ictalurus punctatus, and upamis cyanelll1s. For (;,-8.ch species, diet varied with size and between upper and lower river reaches but not between seasons for Hsh of similar size. Larval chironomids and ccratopogonids were principal foods of most fishes. Copepods and cladocerans...
The known Mountain Plover population breeding on the Myton Bench, Duchesne County, Utah, is small, composed roughly of 30 adults and young after each breeding season. Currently, its location is peripheral to the species? main range. This shrub-steppe breeding habitat differs from the shortgrass prairie habitat with which this bird is historically associated. Between 1996 and 1998 we made observations at nesting sites located consistently in 2 concentrated areas surrounded by large tracts of similar habitat. Activity may be focused in these specific areas because of breeding-site fidelity; this behavior is common among most shorebirds and has been documented for the Mountain Plover in Colorado. Also, Mountain Plovers...
ABSTHAcc--The gastrointestinal tracts, lungs, and urinary bladders from 77 Btlfo microscaphus, 61 Bufo woodJuJUsii, and 8 of their hybrids were examined for helminths. One species of trematode (Glypthelmins quieta), 1 species of cestode (Distoichometra bufonis), and 5 species of nematodes (Aplectana incerta, A. itzocanensis, Rhabdias americanus, Physaloptera sp., and Physocephalus sp.) were found. The greatest prevalence (41%) and mean intensity (231.7) were recorded for Aplectatul incerta in 8u1o woodhousii. It appears hybrids harbor fewer parasites than either parent species. Published in Western North American Naturalist, volume 56, issue 4, on pages 369 - 374, in 1996.
A small numbers of Ospreys (Pandion haliaetus) are known to have nested historically in Utah. A precise baseline figure is unavailable, but the 19th-century Osprey population in Utah probably consisted of at least 15 breeding pairs scattered in 4 geographic regions. Human persecution is believed to have caused the abandonment of nesting territories along the Wasatch Front and in the western Uinta Mountains by 1900 and 1960, respectively. Osprey populations in the southern plateaus and Green River areas, however, began increasing in the late 1970s. Several recent nesting attempts and numerous summer sightings at nontraditional and abandoned historical sites in Utah suggest the Osprey is also expanding its range in...
We compared 3 naturally ignited burns with unburned sites in the Grand Staircase–Escalante National Monument. Each burn site was restored with native and nonnative seed mixes, restored with native seeds only, or regen- erated naturally. In general, burned sites had significantly lower native species richness (1.8 vs. 2.9 species), native species cover (11% vs. 22.5%), and soil crust cover (4.1% vs. 15%) than unburned sites. Most burned plots, seeded or not, had significantly higher average nonnative species richness and cover and lower average native species richness and cover than unburned sites. Regression tree analyses suggest site variation was equally important to rehabilitation results as seeding treatments....
The woundfin is a small, streamlined, omnivorous cyprinid that is now limited to the Virgin River basin where it was collected in the mainstream and one tributary during the present study. The woundfin occurred most frequently in runs and over sand substrates and less frequently in riffles and over rock substrates. It was common over at least half of its original range within the Virgin River. It was uncommon in the lower mainstream due to habitat alterations and, presumably, predation by and competition with exotic species. Published in Western North American Naturalist, volume 38, issue 4, in 1978.
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Carbon isotope discrimination (?) was measured for leaves of Atriplex confertifolia along a salinity gradient in northern Utah. Over this gradient, the variation of ? values was high for a C4 species, and the ? values were positively correlated with salinity in both years of study. Of the possible explanations for this patter, the ? results are consistent with the notion that salinity induces an increase in the bundle sheath leakiness of these C4 plants. Published in Western North American Naturalist, volume 55, issue 2, on pages 135 - 41, in 1995.
Cheatgrass (Bromus tectorum L.) is a dominant weed that has increased the frequency of wildfire in the Great Basin since its introduction about 100 yr ago. This study examines characteristics of respiratory metabolism in several different populations. Seeds from 6 populations were germinated and metabolic heat rates (q) and dark respiration rates (Rco2) of all seedlings were measured calorimetrically at 15° and 25° C or (for 3 populations) at 5° intervals from 5° to 35° C. Growth rates, substrate carbon conversion efficiencies, and Arrhenius temperature coefficients were calculated from the data. Results show that cheatgrass metabolism is most efficient at temperatures near 0° C; at temperatures above 20-25°...
The architecture of burrows of the white-tailed prairie dog (Cynomys leucurus) is poorly known. For this reason and for comparative purposes, one recenlty active burrow of this species was excavated in southern Montana; the detailed methodology is described. Data were compiled on the dimensions of 29.3 m of excavated passages, and interpretations of several features are discussed. A ""turning bay,"" sleeping quarters, two hibernacula, and a maternity area are described, the last feature for the first time in print. In addition, we report Cynomys using their teeth to dig, also for the first time. Further, an inadvertent remodeling of the burrows is ascribed to normal animal traffic and appears to confirm a prediction...
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We evaluated distribution, habitat use, spawning, and species associations of the endangered humpback chub (Gila cypha) in the Yampa and Green rivers, Dinosaur National Monument, from 1986 to 1989. Adult and juvenile humpback chub were captured in high-gradient reaches of Yampa and Whirlpool canyons where they were rare (n = 133, G. robusta) were widely distributed in eddies, pools, runs, and riffles. Humpback chub (n = 39) and roundtail chub (n = 242) in reproductive condition were sympatric in eddy habitats during the 5-6 week period following highest spring runoff. River temperatures at this time averaged about 20 C. Nonnative channel catfish (Ictalurus punctatus) were abundant in eddies yielding humpback and...
This study examined the effects of alterations in soil nitrogen on the growth of Artemessia tridentata ssp. wyomingensis Nutt. Soil nitrogen content was altered by applying sugar (45 g/m2), nitrate (4.5 g/m2), or ammonium (4.5 g/m2), and the results were compared with a control treatment (no soil amendments). Addition of either form of nitrogen significantly increased leaf nitrogen content, mean maximum length of ephemeral leaves, number of ephemeral leaves per terminal shoot, and current year's vegetative stem length over the control and sugar treatments. Both soil water and predawn xylem potentials during active growth were lower in the nitrogen-treated plots. The higher growth activity and greater leaf mass of...
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Erigeron kachinensis is a rare endemic of the Colorado Plateau in southeastern Utah. This perennial composite grows in small, isolated populations at seeps and alcoves arising along canyon walls in Cedar Mesa Sandstone substrates. Characteristics of six Erigeron kachinensis sites in Natural Bridges National Monument, San Juan County, Utah, were studied to determine habitat requirements for this species. Sites were analyzed with respect to geology, soil chemistry, physical properties, and vegetational characteristics. The alcoves studied were very saline, often with soil surfaces covered with a white crust of salt. Living cover was enhanced by perennially moist soils, diminished amounts of solar radiation, soil salinity,...
We demonstrate new multi-phase, multi-scale approaches for sampling and modeling native and exotic plant species to predict the spread of invasive species and aid in control efforts. Our test site is a 54,000-ha portion of Rocky Mountain National Park, Colorado, USA. This work is based on previous research wherein we developed vegetation sampling techniques to identify hot spots of diversity, important rare habitats, and locations of invasive plant species. Here we demonstrate statistical modeling tools to rapidly assess current patterns of native and exotic plant species to determine which habitats are most vulnerable to invasion by exotic species. We use stepwise multiple regression and modified residual kriging...
Cryptogamic soil crusts of Betatakin Canyon in Navajo National Monument were investigated to understand the influence of such crusts on soil moisture relationships and potential sediment production. Crusts sampled were part of the pinyon-juniper community and were studied in paired units. The presence of crusts on soils significantly increased the depth of water penetration and decreased runoff. Soils showed reduced infiltration of water where lichen and algal crusts were present and enhanced infiltraion rates where mosses were present. Crusts appear to cause surface sealing and therefore likely reduce surface evaporation rates as well. Published in Western North American Naturalist, volume 43, issue 1, on pages...
Eight general study sites in the blackbrush (Coleogyne ramosissima) zone of southwestern Utah were examined. Soils data were gathered and plant cover was estimated. Shrubs were found to he positively correlated with shallow, sandy soil. Nonwoody plants were found to be positively correlated with deeper, silty soils. Cryptogamic soil crusts were positively correlated with silt and nitrogen in the soil and therefore may play a role in elevating soil fertility. Shrubs and grasses were negatively correlated. Management implications are discussed. Published in Western North American Naturalist, volume 45, issue 2, in 1985.
Fertilized ova of razorback sucker, Xyrauchen texanus, were adhesive for 3 to 4 hours after fertilization. Cleavage was completed at 24 hours, gastrulation occurred at 34 hours, and blood circulation was established at 117 hours. Hatching occurred from 5.2 to 5.5 days after fertilization. Larvae were from 6.8 to 7.3 mm TL at hatching. Yolk was assimilated at 13 days (10 mm TL). All fins were formed and had ossified rays at 64 days (27 mm TL). The unique nuchal keel appeared about 200 days after fertilization. Published in Western North American Naturalist, volume 42, issue 4, in 1982.
Chemical composition of some major forage plants of mountain summer ranges of southeastern Utah is reported. Grasses are shown to contain significantly less nitrogen, phosphorus, potassium, calcium, and magnesium than either forbs or shrubs. Forbs and shrubs are demonstrated to differ significantly only in potassium content; forbs tested contained more potassium than shrubs. The chemical composition of the forage plants is discussed in relation to mule deer reproductive rates. It is concluded that protein and mineral content of the forage of the two ranges considered (the LaSal and Henry mountains) is less likely to affect reproductive rates than is the relative digestibility of grasses, forbs, and shrubs. Published...
map background search result map search result map Habitat requirements for Erigeron kachinensis, a rare endemic of the Colorado Plateau Humpback chub ( Gila cypha ) in the Yampa and Green rivers, Dinosaur National Monument, with observations on roundtail chub ( G. robusta ) and other sympatric fishes Carbon isotope discrimination in the C4 shrub Atriplex confertifolia along a salinity gradient Habitat requirements for Erigeron kachinensis, a rare endemic of the Colorado Plateau Humpback chub ( Gila cypha ) in the Yampa and Green rivers, Dinosaur National Monument, with observations on roundtail chub ( G. robusta ) and other sympatric fishes Carbon isotope discrimination in the C4 shrub Atriplex confertifolia along a salinity gradient