Pacific Mountain Research Articles

Energy-Magnitude Station Corrections across the Conterminous United States

Abstract The determination of source parameters requires corrections for propagation and site effects. The source parameter of interest for this study is the radiated seismic energy, which we use in turn to compile a global energy magnitude Me catalog. The energy estimated for P waves recorded at distances between 20° and 98° is corrected for propagation effects using the numerical Green’s function for the AK135Q model, in which the correction is performed in the spectral domain over the frequency range 0.012–1 Hz. To quantify the impact of site effects on Me, we perform a mixed-effects regression to isolate repeated station effects from event and propagation contributions to the overall magnitude variability. We find that the standard deviation of the interstation residuals is 0.19, whereas the standard deviation of the path-to-path residuals is 0.24. To discuss the spatial variability of the station-specific magnitude residuals, we analyze the results obtained for permanent and temporary networks installed in the conterminous United States. The high density of stations considered (4502 stations from 97 networks) allows us to compare a map of the station corrections with the physiographic classification of the United States. We find a good agreement, with positive magnitude corrections for stations installed in the Atlantic Plain and in the Interior Plains divisions; negative corrections characterize installations in the Rocky Mountains system, in the Interior Highlands, in the ranges of the Pacific Mountains division and in the Appalachian Highlands. Moreover, the alternation of positive and negative magnitude corrections corresponds well with the province and section subdivisions.

Historical analysis of timber exploitation in the Central Pacific Mountains of Costa Rica

Abstract [Introduction] The mountainous region of the Central Pacific of Costa Rica, currently made up mostly of the cantons of Turrubares, Puriscal and Mora, and to a lesser extent by the southwest of Acosta, was one of the most deforested areas since colonial times. [Objective] To comprehensively analyze the historical, socioeconomic, geo-climatic and ecological factors that possibly favored the logging exploitation of the forests of that region. [Methodology] The historical documents, and the geo-climatic, ecological and socioeconomic factors of the region were reviewed. In addition, a census was carried out among forestry professionals and industrialists to determine the timber species possibly extracted from the forests based on the floristic composition of protected forest areas in the region. [Results] The mountainous region was a transit and settlement site for Spanish colonists since the 16th century, which facilitated the development of access roads. Its proximity to the Central Valley, which needed forest and agricultural products for the growing urban area, together with the existence of an ecological convergence zone extraordinarily rich in trees of commercial importance, greatly facilitated the extraction of forest products. [Conclusion] The early colonization of the region, the existence of infrastructure, high demand for forest products at the national and international level, and the availability of forest resources in an area where the tropical dry forest, the cloud forest and the humid forest converge, and the edaphoclimatic conditions that also facilitated the development of agricultural crops, favored the change in land use and therefore the forestry exploitation of the region.

Human or climate? Differentiating the anthropogenic and climatic drivers of lake storage changes on spatial perspective via remote sensing data

Lakes are an essential part of the terrestrial water system in which storage changes are controlled by water balance and human impact. Although there are some attempts to define storage changes on a global scale, examination of spatial relations is poorly quantified. In this study, therefore, lake storage changes have been investigated using remote-sensing-derived data around the globe. Hence, 372 artificial/natural lakes were obtained, covering between 1992 and 2019. Watersheds belong to river was extracted via HydroSHED data. Based on watershed, dominant climate types were determined via Köppen-Geiger classification. Similarly, the areal average CRU TS v.4.05 monthly gridded precipitation time series and human footprint data based on watersheds were obtained to understand the drivers of lake storage changes. The nonparametric Mann-Kendall and Sen's slope trend analyses were applied to the lake storage change and precipiation values in order to determine long-term increases and decreases. A bivariate map was constructed between storage changes trend vs precipitation trend and human footprint to reveal the drivers of lake storage changes in terms of spatial aspects. The trend analysis and bivariate map results show that North America, the East African Highlands, and the Tibet plateau are important increasing hotspots, where precipitation is a significant driver for storage oscillations, except for the Tibet plateau. Besides, the Brazilian Highlands, Pacific Mountain System, and Intermontane of conterminous USA are other decreasing hotspots in which human footprint and decreasing precipitation collectively affect these changes. Furthermore, results clearly show that anthropogenic influence is low in the northern and mountainous areas, and storage changes have a linear relationship with precipitation. In contrast, intense human climate interaction influences lake changes in plains areas and arid/temperate climates.

Contrasting genetic trajectories of endangered and expanding red fox populations in the western U.S

As anthropogenic disturbances continue to drive habitat loss and range contractions, the maintenance of evolutionary processes will increasingly require targeting measures to the population level, even for common and widespread species. Doing so requires detailed knowledge of population genetic structure, both to identify populations of conservation need and value, as well as to evaluate suitability of potential donor populations. We conducted a range-wide analysis of the genetic structure of red foxes in the contiguous western U.S., including a federally endangered distinct population segment of the Sierra Nevada subspecies, with the objectives of contextualizing field observations of relative scarcity in the Pacific mountains and increasing abundance in the cold desert basins of the Intermountain West. Using 31 autosomal microsatellites, along with mitochondrial and Y-chromosome markers, we found that populations of the Pacific mountains were isolated from one another and genetically depauperate (e.g., estimated Ne range = 3–9). In contrast, red foxes in the Intermountain regions showed relatively high connectivity and genetic diversity. Although most Intermountain red foxes carried indigenous western matrilines (78%) and patrilines (85%), the presence of nonindigenous haplotypes at lower elevations indicated admixture with fur-farm foxes and possibly expanding midcontinent populations as well. Our findings suggest that some Pacific mountain populations could likely benefit from increased connectivity (i.e., genetic rescue) but that nonnative admixture makes expanding populations in the Intermountain basins a non-ideal source. However, our results also suggest contact between Pacific mountain and Intermountain basin populations is likely to increase regardless, warranting consideration of risks and benefits of proactive measures to mitigate against unwanted effects of Intermountain gene flow.

Glacier retreat creating new Pacific salmon habitat in western North America

Glacier retreat poses risks and benefits for species of cultural and economic importance. One example is Pacific salmon (Oncorhynchus spp.), supporting subsistence harvests, and commercial and recreational fisheries worth billions of dollars annually. Although decreases in summer streamflow and warming freshwater is reducing salmon habitat quality in parts of their range, glacier retreat is creating new streams and lakes that salmon can colonize. However, potential gains in future salmon habitat associated with glacier loss have yet to be quantified across the range of Pacific salmon. Here we project future gains in Pacific salmon freshwater habitat by linking a model of glacier mass change for 315 glaciers, forced by five different Global Climate Models, with a simple model of salmon stream habitat potential throughout the Pacific Mountain ranges of western North America. We project that by the year 2100 glacier retreat will create 6,146 (±1,619) km of new streams accessible for colonization by Pacific salmon, of which 1,930 (±569) km have the potential to be used for spawning and juvenile rearing, representing 0 to 27% gains within the 18 sub-regions we studied. These findings can inform proactive management and conservation of Pacific salmon in this era of rapid climate change.

Mantle plumes, triple junctions and transforms: A reinterpretation of Pacific Cretaceous – Tertiary LIPs and the Laramide connection

The Shatsky and Hess Rises, the Mid-Pacific Mountains and the Line Islands large igneous provinces (LIPs) present different challenges to conventional plume models. Resolving the genesis of these LIPs is important not only for a more complete understanding of mantle plumes and plume-generated magmatism, but also for establishing the role of subducted LIP conjugates in the evolution of the Laramide orogeny and other circum-Pacific orogenic events, which are related to the development of large porphyry systems. Given past difficulties in developing consistent geodynamic models for these LIPs, it is useful to consider whether viable alternative geodynamic scenarios may be provided by recent concepts such as melt channel networks and channel-associated lineaments, along with the “two mode” model of melt generation, where a deeply-sourced channel network is superimposed on the plume, evolving and adapting over millions of years. A plume may also interact with transform faults in close proximity to a mid ocean ridge, with the resultant bathymetric character strongly affected by the relative age difference of lithosphere across the fault.Our results suggest that the new two-mode melt models resolve key persistent issues associated with the Shatsky Rise and other LIPs and provide evidence for the existence of a conduit system within plumes that feed deeply-sourced material to the plume head, with flow maintained over considerable distances. The conduit system eventually breaks down during plume – ridge separation and may do so prior to the plume head being freed from the triple junction or spreading ridge. There is evidence for not only plume head capture by a triple junction but also for substantial deformation of the plume stem as the distance between the stem and anchored plume head increases. The evidence suggests that young transforms can serve as pathways for plume material migration, at least in certain plume head – transform configurations. A fortuitous similarity between the path of the Shatsky and Sio plumes, with respect to young spreading ridges and transforms, helps to clarify previously problematic bathymetric features that were not readily ascribed to fixed plumes alone. The Line Island Chain, which has been the subject of a vast number of models, is related mainly to several plumes that passed beneath the same region of oceanic crust, a relatively rare event that has resulted in LIP formation rather than a regular seamount track.Our findings have important implications for the timing and mechanism for the Laramide Orogeny in North America, demonstrating that the Hess Rise conjugate may be much smaller than traditionally thought. The Mid Pacific Mountains conjugate may not exist at all, given large parts of these LIPs were formed at an ‘off-ridge’ site. This needs to be taken into account while considering the effects of conjugate collision on mineralization and orogenic events.

Two new species of Pleurothallis (Orchidaceae: Pleurothallidinae) from Costa Rica in the P. phyllocardia group

Two new species of Pleurothallis subsection Macrophyllae-Fasciculatae from Costa Rica are described and illustrated, and their relationships discussed. Pleurothallis pudica, from the central Pacific mountain region, is compared with P. phyllocardia, but it is easily recognized by the densely pubescent- hirsute flowers. Pleurothallis luna-crescens, from the Caribbean slope of the Talamanca chain, is compared with P. radula and P. rectipetala, from which it is distinguished by the dark purple flowers and the distinctly longer, dentate petals, respectively. A key to the species of the group in Costa Rica and western Panama is presented.

Ten-year climatological features and air origin of midlatitude double tropopauses

The 10-year climatological features related to midlatitude double tropopause events (DTs) are examined using ERAInterim data from 2003 to 2012. The analysis is based on tropopauses defined by lapse rate. Results show that DTs are permanent or semi-permanent in the midlatitudes, and high DT frequency bands move poleward in winter and equatorward in summer, which is consistent with the seasonal movement of the subtropical jet. Based on our statistics, the second tropopause is found at about 100 hPa in the subtropics and at slightly lower altitudes in sub-polar regions. The thickness between the first and second tropopause is smaller in the subtropics and increases with latitude. Next, the origin of air sandwiched between the first and second tropopause of DTs is studied with a revised version of the UK Universities Global Atmospheric Modelling Programme Offline Trajectory Code (Version 3) diabatic trajectory model. The results show that, in the lower or middle troposphere, air is transported into the DTs from lower latitudes, mainly in the tropics. The dominant source regions are mainly areas of deep convection and steep orography, e.g., the western Pacific and Himalayan Mountains, and they show strong seasonality following the seasonal shift of these strong upwelling regions.

Geographic variation in contact calls emitted by a leaf-roosting bat suggest distinct modes of vocal transmission

Group behaviors, such as coordination and information exchange, are typically mediated by acoustic signals known as contact calls. Although these vocalizations are widespread, the mechanisms driving variation in acoustic features within and between populations remain poorly understood. Our study examines whether patterns of variation in two contact calls emitted by Spix’s disk winged bats, Thyoptera tricolor, are congruent with patterns of genetic distance among populations isolated by a geographic barrier. T. tricolor is a leaf roosting bat that forms stable social groups and exhibits all-offspring philopatry. To evaluate if vocal variation between groups is influenced by genetic distance, we studied the variation in microsatellite allele frequencies at multiple sites on the Caribbean and Pacific mountain slopes. We found that the geographic variation patterns differed between the two types of calls studied, and we argue that this indicates distinct modes of vocal transmission. Our results suggest that one contact call is likely socially transmitted via vocal learning, while the congruence between patterns of genetic differentiation and acoustic variation for the second call type suggest this is an inherited trait. Further research is needed to better understand the role of vocal learning and genetic transmission of contact calls emitted by T. tricolor.

Geomorphological tension of the Central Andes

Mapping and regional analysis of the "geomorphological tension" were made for the territory of the central fragment of the continental margin mountain system of the Andes (latitude between 5 ° S – 19 ° S). We determine the geomorphological tension as a susceptibility of the territory to the development of catastrophic processes. According to the regional level of generalization tension was evaluated in ordinal scores. Assessment was based on the analysis of seismicity, amount of precipitation, the depth of the relief dissection, and the spectrum of the dominant geomorphic processes. On the base of the results of mapping on the scale of 1:8 million it was determined that zone of maximum geomorphological tension is situated at the Western megaslope of the Peruvian Andes between latitudes 9 ° S and 13 ° 30’S and in the band width of 100 km from the Pacific coast. Its value here reaches 15-16 scores due to natural causes. The tension on the Eastern megaslope of the Andes ranges from 9 to 12 points, except for some areas where it rises to 13-14, and for the Altiplano where it decrease to 6-10 points. An important feature of the study area is the asymmetric distribution of geomorphological processes and the geomorphological tension, which differ significantly at the oceanic and the inland slopes of the mountain range. Comparison of data obtained for the two segments (NW and SE) of the circum pacific mountain belt allows concluding about the existence of its geomorphological tension general regularities. The areas of potential catastrophic processes are located near the margin of the continent in either case.

Niche conservatism in the Mesoamerican seasonal tropical dry forest orchid Barkeria (Orchidaceae)

The aim of this paper is to investigate if speciation in allopatric species in Barkeria occurred in a scenario of ecological niche conservatism. Barkeria is a Mesoamerican orchid genus with fifteen species found in scattered forests in the Pacific mountains of Mesoamerica. Most species grow in seasonal tropical dry forests and a few also occupy oak, pine and pine-oak forests. Phylogenetic, molecular dating, ecological niche modeling and niche conservatism analyses were performed to determine phylogenetic relationships among species and to test for patterns between species relatedness and ecological niche traits. Bayesian phylogenetic analyses were conducted with nuclear and plastid DNA markers. Ecological niche modeling was run in MaxEnt. Evolutionary models of niche and climatic distances were estimated to determine if the niches in the Barkeria tree were conserved and if speciation in pairs of allopatric sister species retrieved in the phylogeny was influenced by climate. Barkeria is a young genus that has colonized the Pacific dry forest since the middle Pliocene to the Pleistocene. The fit of the phylogenetic Barkeria tree to a stasis model of evolution as well as the lack of phylogenetic signal under a Brownian motion model suggest strong niche conservatism of its species. However, factors other than climate influenced speciation in the allopatric sister species. The patchy distribution and differences in the vegetation of tropical dry forests of Mesoamerica as well as geographical barriers may have influenced speciation in Barkeria.

Acute Inflammation Responses to Eccentric Exercise in Normal Versus Overweight Individuals

Basal inflammation associates with body mass index (BMI), but whether acute inflammation responses differ between normal and overweight individuals is not clear. PURPOSE: To determine whether plasma/serum cytokine and cortisol responses differ between normal and overweight individuals after eccentric exercise. METHODS: College-aged men and women (n=45) classified as normal weight (BMI 18-25 kg·m-2, n=33) and overweight (BMI 25-30 kg·m-2, n=12) completed exercise and control conditions in random order. The exercise condition consisted of a three sets of 15 maximal eccentric actions using the elbow flexor muscles of one arm, and blood was collected pre-, 4, 8, 12, and 23 h post-exercise at 7:00 a.m., 12:00, 4:00, 8:00 p.m., and 7:00 a.m. Blood was collected on a time-matched schedule without exercise for the control condition. Serum and plasma were analyzed for soluble tumor necrosis factor receptor-1 (sTNFR1), interleukin-6 (IL-6), soluble gp130 (sgp130), C-reactive protein (CRP), and cortisol. RESULTS: There were no resting inflammation differences between normal and overweight groups. sTNFR1 was approximately 10% higher (P<0.05) in the exercise compared to control condition 8, 12, and 24 h post-exercise in the overweight group and did not differ between conditions in the normal weight group. IL-6 was higher in the exercise compared to control condition 4, 8, 12, and 24 h post-exercise with no difference between groups. No differences between groups were detected for sgp130 or CRP. Cortisol was lower 4 h post-exercise in the exercise compared to the control condition and was greater in the normal compared to overweight group at 7:00 a.m. on the second morning of the control condition. CONCLUSIONS: The acute inflammation response following eccentric exercise differed between normal and overweight groups. Of the variables measured, sTNFR1 was the most sensitive to differences in BMI. Supported by a grant from the American Heart Association Pacific Mountain Affiliate.

Nonmethane hydrocarbons at Pico Mountain, Azores: 1. Oxidation chemistry in the North Atlantic region

Measurements of nonmethane hydrocarbons (NMHC) at the Pico Mountain observatory at 2225 m asl on Pico Island, Azores, Portugal, from August 2004 to August 2005 (in part overlapping with the field campaign of the International Consortium on Atmospheric Research on Transport and Transformation study) were used to investigate NMHC sources and seasonal oxidation chemistry in the central North Atlantic region. Levels of anthropogenic NMHC were characteristic of the marine free troposphere. Their concentrations were low compared to continental sites at higher northern latitudes, but higher than data reported from a similarly located Pacific mountain site at Mauna Loa Observatory, Hawaii. These higher NMHC levels are indicative of a greater influence of the adjacent continents on air composition at Pico. Substantially enhanced NMHC concentrations during the summers of 2004 and 2005 were attributed to long‐range transport of biomass burning plumes originating from fires in northern Canada, Alaska, and Siberia. This finding exemplifies the continuing impact of biomass burning plumes on atmospheric composition and chemistry many days downwind of these emission sources. Seasonal cycles with lower NMHC concentrations and lower ratios of more reactive to less reactive NMHC during summer reflect the higher degree of photochemical processing occurring during transport. The NMHC concentrations indicate no significant role of chlorine atom oxidation on NMHC. Ozone above 35 ppbv was measured at Pico Mountain throughout all seasons. Enhanced ozone levels were observed in air that had relatively “fresh” photochemical signatures (e.g., ln [propane]/[ethane] &gt; −2.5). During spring‐summer air that was more processed (“older” air with ln [propane]/[ethane] &lt; −2.5) on average had lower ozone levels (down to &lt;20 ppbv). This relationship indicates that conditions in the lower free troposphere over the mid–North Atlantic during the spring and summer lead to net photochemical ozone destruction while air is photochemically aging during transport to Pico. This behavior contrasts to that in the mid–North Pacific where other recent studies have found that the photochemistry is more nearly ozone neutral.

Historical Glacier and Climate Fluctuations at Mount Hood, Oregon

Terminus fluctuations of five glaciers and the correspondence of these fluctuations to temperature and precipitation patterns were assessed at Oregon’s Mount Hood over the period 1901–2001. Historical photographs, descriptions, and climate data, combined with contemporary GPS measurements and GIS analysis, revealed that each glacier experienced overall retreat, ranging from −62 m at the Newton Clark Glacier to −1102 m at the Ladd Glacier. Within this overall trend, Mount Hood’s glaciers experienced two periods each of retreat and advance. Glaciers retreated between 1901 and 1946 in response to rising temperatures and declining precipitation. A mid-century cool, wet period led to glacier advances. Glaciers retreated from the late 1970s to the mid-1990s as a result of rising temperatures and generally declining precipitation. High precipitation in the late 1990s caused slight advances in 2000 and 2001. The general correspondence of Mount Hood’s glacier terminus fluctuations with glaciers in Washington and Oregon suggests that regional, decadal-scale weather and climate events, driven by the Pacific Decadal Oscillation, play a key role in shaping atmosphere-cryosphere interactions in Pacific Northwest mountains. Deviations from the general glacier fluctuation pattern may arise from local differences in glacier aspect, altitude, size, and steepness as well as volcanic and geothermal activity, topography, and debris cover.

Comparative Susceptibility of Conifers to Western Hemlock Dwarf Mistletoe in the Cascade Mountains of Washington and Oregon

Abstract A total of 24 mixed conifer stands in Washington and Oregon infested with western hemlock dwarf mistletoe (Arceuthobium tsugense subsp. tsugense) were sampled to compare host susceptibility to this parasitic plant. Temporary circular plots were established around dominant, severely infected western hemlocks (Tsuga heterophylla). Within plots, species, diameter at breast height, and dwarf mistletoe rating (6-class system) were determined for each live tree. More than 5,700 trees were sampled in 275 plots. Based on the incidence of infection, tree species were assigned to host susceptibility classes. Western hemlock is classified as the only principal host of western hemlock dwarf mistletoe. Pacific silver fir (Abies amabilis), noble fir (Abies procera), and mountain hemlock (Tsuga mertensiana) are classified as occasional hosts. Resource managers can use the host susceptibility classifications based on this study for decisions regarding which trees to retain when selectively harvesting mixed conifer stands infested with western hemlock dwarf mistletoe in the Pacific Northwest. West. J. Appl. For. 20(2):94–100.

Community and University Participation in Disaster-Relief Recovery

Marginalized groups that are traditionally excluded from policy and decision-making are often also disproportionately affected by the hardships of natural disasters. By including community residents in research and planning, public health practitioners and researchers can create programs that have immediate relevance and policy implications. This article describes a case study of the formation of a community-uniStephanie Farquhar is Assistant Professor, Portland State University, School of Community Health, 450F Urban Center, 506 Mill Street, Portland, OR 97207-0751. At the time of the study, Dr. Farquhar was a W.K. Kellogg Postdoctoral Fellow, University of North Carolina at Chapel Hill. Noelle Dobson is Program Manager, Active Living by Design, American Heart Association, Pacific Mountain Affiliate, Portland, OR. Address correspondence to: Stephanie Farquhar, PhD (E-mail: farquhar@pdx.edu). Portions of this article were adapted with permission from a book chapter written by Farquhar, S.A., and Wing, S. (2002). Methodological and ethical considerations of community-driven environmental justice research: Examination of two case studies from rural North Carolina. In M. Minkler & N. Wallerstein (Eds.), Community-based participatory research for health (pp. 221-241). New York: Jossey Bass. This material is used by permission of John Wiley & Sons, Inc. versity partnership and a community-based participatory research project conducted in the aftermath of Hurricane Floyd. The description of methods used and the implications for practice will highlight the importance of including those most affected by a natural disaster. Members of several groups worked collaboratively to define the social and public health concerns of a rural North Carolina community and to create changes in disaster-recovery policy and practice.

Snow Avalanche Climatology of the Western United States Mountain Ranges

Abstract The snow avalanche climate of the western United States has long been suspected to consist of three main climate zones that relate with different avalanche characteristics: coastal, intermountain, and continental. The coastal zone of the Pacific mountain ranges is characterized by abundant snowfall, higher snow densities, and higher temperatures. The continental zone of the Colorado Rockies is characterized by lower temperatures, lower snowfall, lower snow densities, higher snow temperature gradients, and a more persistently unstable snowpack resulting from depth hoar. The intermountain zone of Utah, Montana, and Idaho is intermediate between the other two zones. A quantitative analysis of snow avalanche climate of the region was conducted based on Westwide Avalanche Network data from 1969 to 1995. A binary avalanche climate classification, based on well–known thresholds and ranges of snowpack and climatic variables, illustrates the broadscale climatology of the three major zones, some spatially ...

THE SPECIES OF THE NORTH AMERICAN LEAFHOPPERSCERATAGALLIAKIRKALDY ANDACERATAGALLIAKIRKALDY (RHYNCHOTA: HOMOPTERA: CICADELLIDAE)

AbstractThe North American genusCeratagalliaKirkaldy, 1907 is redefined to include subgenusAceratagalliaKirkaldy, 1907 (=IoniaBall, 1933, syn.nov.) with 78 species in two subgenera. Two additional new species are unplaced to subgenus:C. aceratafrom Oregon, andC. emarginatafrom Mexico. The typical subgenusCeratagalliahas 30 species, includingC. gillettei(Osborn &amp; Ball, comb.nov.),C. sordida(Oman, comb.nov.), and two new speciesC. anafrom Mexico andC. viperafrom Washington state. SubgenusAceratagalliahas 46 species, all new combinations underCeratagallia. The economic "species" formerly known as "sanguinolenta" is divided into the Canadian clover leafhopperC. humilis(Oman) and the American clover leafhopperC. agricolasp.nov. Other new taxa in subgenusAceratagalliainclude 18 new species and seven new subspecies:alaskana(ssp. ofsiccifolia)from Alaska;omanion the Pacific coast from Oregon to British Columbia;clinoandlophiafrom the Oregon interior;compressa(ssp. ofsiccifolia),gallus,modesta,okanagana, andzacki(ssp. ofnanella) from intermontane valleys of the Pacific northwest and southwestern mountains;interior(ssp. ofhumilis) androssifrom the Sonoran subregion;australis(ssp. ofnanella),coma,ebena,entoma,falcata,oionus, andvenosafrom Mexico and Texas;alvarana(ssp. ofhumilis),cerea,cristula,harrisi, semiarida, andviatorwidespread between the Appalachian and Rocky Mountains; andwhitcombi(ssp. ofrobusta) from Florida to Arizona. Four former species are reduced to subspecies:compactaOman andpoudrisOman inC. robusta(Oman),helveolaOman inC. cinerea(Osborn &amp; Ball), andtruncataOman inC. humilis. The taxa are keyed and illustrated, and their phylogeny is discussed.

The Distribution of Western North American Hepaticae. Endemic Taxa and Taxa with a North Pacific Arc Distribution

The Distribution of Western North American Hepaticae. Endemic Taxa and Taxa with a North Pacific Arc Distribution

Quantitative estimation of undiscovered mineral resources; a case study of U. S. Forest Service wilderness tracts in the Pacific mountain system

The need by land managers and planners for more quantitative measures of mineral values has prompted scientists at the U.S. Geological Survey to test a probabilistic method of mineral resource assessment on a portion of the wilderness lands that have been studied by the Survey during the past 20 years. A quantitative estimate of undiscovered mineral resources is made by linking the techniques of subjective estimation, geologic mineral deposit models, and Monte Carlo simulation. The study, which uses grade-tonnage and occurrence models for 21 geologic deposit types, considers 91 U.S. Forest Service wilderness tracts in California, Nevada, Oregon, and Washington. Estimates of the amounts of the 11 metals contained in undiscovered mineral deposits of the types studied range from negligible to several years of U.S. consumption. Although these estimates are limited to metals contained in undiscovered deposits of a small number of metallic mineral deposit types, the assessment procedure can be expanded by the use of additional deposit models and by using information about identified mineral resources. This will allow models of economic processes such as exploration, development, and production to be applied.