US Rocky Research Articles

Wolf (Canis lupus) Predation Impacts on Livestock Production: Direct Effects, Indirect Effects, and Implications for Compensation Ratios

Growing wolf (Canis lupus L.) populations in the US Rocky Mountain Region have increased conflicts between livestock production and wolf conservation. Given that the costs of large carnivore conservation are disproportionately borne by local livestock producers, the United States uses compensation for wolf damage to reduce conflicts and mediate negative attitudes toward the predators. Current compensation programs, however, only consider the direct effects of wolf predation. Indirect effects, such as wolf effects on weaning weights, and conception rates, may also reduce profitability. By not including indirect wolf effects, compensation programs may systematically undercompensate ranchers. We use a stochastic budget model of a representative cow–calf ranch in northwest Wyoming to estimate the economic impact of both direct (death loss and injured calves) and indirect effects (decreased weaning weights, decreased conception rates, and increased cattle sickness) of wolf predation. Our results suggest that short-run (i.e., year-to-year) financial impacts of wolf indirect effects may be as large as or larger than the direct effects. Including indirect effects implies that the compensation ratio (i.e., number of calves compensated per confirmed depredation) necessary to fully offset the financial impacts of wolves would need to be two to three times larger than current 7:1 compensation ratio used in Wyoming.

Stand- and landscape-scale selection of large trees by fishers in the Rocky Mountains of Montana and Idaho

The fisher (Pekania pennanti; formerly known as Martes pennanti) is a North American endemic mustelid with a geographic distribution that spans much of the boreal forests of North America. In the Northern Rocky Mountain (NRM) fishers have been the focus of Endangered Species Act (ESA) listing decisions. Habitat studies of West Coast fishers in California have consistently identified late-successional forests as important, providing direct implications for forest management and fisher conservation. In the NRM range very little is known about the habitat selection patterns of fishers relative to forest age and species composition, yet ESA petitioners have repeatedly listed habitat loss and destruction as the primary threat to fisher persistence. Between 2002 and 2006 we studied NRM fishers in the Clearwater sub-basin and eastern slope of the Bitterroot-Selway Ecosystem in Idaho and Montana. We used radio-telemetry locations from collared fishers to document fisher habitat use. We developed candidate models describing tree size, species composition, canopy closure, structural diversity, and topography to assess patterns of habitat selection relative to topographic and vegetative predictor variables measured at both stand and landscape scales. Support for these models was evaluated using Akaike Information Criteria. Fishers disproportionately used both stand sites and regional landscapes characterized by large diameter trees and avoided areas with ponderosa (a shade-intolerant species characteristic of xeric sites in the NRM) and lodgepole pine according to our best supported model. These results are consistent with other studies in the western US and Canada where large trees were deemed important, although we show that this selection in the Rocky Mountains occurs at multiple scales. These results highlight the importance of late-successional forests, consistent with a recent conservation strategy for fishers, and the importance of both stand- and landscape-level factors when directing forest management of fisher habitat in the US Rocky Mountains.

Future humidity trends over the western United States in the CMIP5 global climate models and variable infiltration capacity hydrological modeling system

Abstract. Global climate models predict relative humidity (RH) in the western US will decrease at a rate of about 0.1–0.6 percentage points per decade, albeit with seasonal differences (most drying in spring and summer), geographical variability (greater declines in the interior), stronger reductions for greater anthropogenic radiative forcing, and notable spread among the models. Although atmospheric moisture content increases, this is more than compensated for by higher air temperatures, leading to declining RH. Fine-scale hydrological simulations driven by the global model results should reproduce these trends. It is shown that the MT-CLIM meteorological algorithms used by the Variable Infiltration Capacity (VIC) hydrological model, when driven by daily Tmin, Tmax, and precipitation (a configuration used in numerous published studies), do not preserve the original global model's humidity trends. Trends are biased positive in the interior western US, so that strong RH decreases are changed to weak decreases, and weak decreases are changed to increases. This happens because the MT-CLIM algorithms VIC incorporates infer an overly large positive trend in atmospheric moisture content in this region, likely due to an underestimate of the effect of increasing aridity on RH. The result could downplay the effects of decreasing RH on plants and wildfire. RH trends along the coast have a weak negative bias due to neglect of the ocean's moderating influence. A numerical experiment where the values of Tdew are altered to compensate for the RH error suggests that eliminating the atmospheric moisture bias could, in and of itself, decrease runoff up to 14% in high-altitude regions east of the Sierra Nevada and Cascades, and reduce estimated Colorado River runoff at Lees Ferry up to 4% by the end of the century. It could also increase the probability of large fires in the northern and central US Rocky Mountains by 13 to 60%.

Spatial scaling of wildland fuels for six forest and rangeland ecosystems of the northern Rocky Mountains, USA

Wildland fuels are important to fire managers because they can be manipulated to achieve management goals, such as restoring ecosystems, decreasing fire intensity, minimizing plant mortality, and reducing erosion. However, it is difficult to accurately measure, describe, and map wildland fuels because of the great variability of wildland fuelbed properties over space and time. Few have quantified the scale of this variability across space to understand its effect on fire spread, burning intensity, and ecological effects. This study investigated the spatial variability of loading (biomass) across major surface and canopy fuel components in low elevation northern Rocky Mountain forest and rangeland ecosystems to determine the inherent scale of surface fuel and canopy fuel distributions. Biomass loadings (kg m−2) were measured for seven surface fuel components—four downed dead woody fuel size classes (0–6 mm, 6–25 mm, 25–75 mm, and 75 + mm), duff plus litter, shrub, and herb—using a spatially nested plot sampling design within a 1 km2 square sampling grid installed at six sites in the northern US Rocky Mountains. Bulk density, biomass, and cover of the forest canopy were also measured for each plot in the grid. Surface fuel loadings were estimated using a combination of photoload and destructive collection methods at many distances within the grid. We quantified spatial variability of fuel component loading using spatial variograms, and found that each fuel component had its own inherent scale with fine fuels varying at scales of 1–5 m, coarse fuels at 10–150 m, and canopy fuels from 100 to 500 m. Using regression analyses, we computed a scaling factor of 4.6 m for fuel particle diameter (4.6 m increase in scale with each cm increase in particle diameter). Findings from this study can be used to design fuel sampling projects, classify fuelbeds, and map fuel characteristics, such as loading, to account for the inherent scale of fuel distributions to get more accurate fuel loading estimations.

Phenotypic plasticity and adaptive evolution contribute to advancing flowering phenology in response to climate change

Anthropogenic climate change has already altered the timing of major life-history transitions, such as the initiation of reproduction. Both phenotypic plasticity and adaptive evolution can underlie rapid phenological shifts in response to climate change, but their relative contributions are poorly understood. Here, we combine a continuous 38 year field survey with quantitative genetic field experiments to assess adaptation in the context of climate change. We focused on Boechera stricta (Brassicaeae), a mustard native to the US Rocky Mountains. Flowering phenology advanced significantly from 1973 to 2011, and was strongly associated with warmer temperatures and earlier snowmelt dates. Strong directional selection favoured earlier flowering in contemporary environments (2010-2011). Climate change could drive this directional selection, and promote even earlier flowering as temperatures continue to increase. Our quantitative genetic analyses predict a response to selection of 0.2 to 0.5 days acceleration in flowering per generation, which could account for more than 20 per cent of the phenological change observed in the long-term dataset. However, the strength of directional selection and the predicted evolutionary response are likely much greater now than even 30 years ago because of rapidly changing climatic conditions. We predict that adaptation will likely be necessary for long-term in situ persistence in the context of climate change.

Snowpack and precipitation chemistry at a high altitude site in the Canadian Rocky Mountains

Summary This study presents a first quantitative study of inorganic ion concentrations and loading in precipitation in the Canadian Rocky Mountains. The 2005/2006 winter snowpack and July 2006 rainfall are examined to define the magnitude, and altitudinal and seasonal variability of atmospheric deposition at high altitude sites. Little is currently known about the sources and concentrations of inorganic ions in watersheds in this region, and careful measurement of snowpack and rainfall chemistry are required to accurately assess the total annual deposition and the potential environmental effects of atmospheric pollution on high elevation ecosystems and snowmelt-dominated catchments on both sides of the continental divide. Snowpit profiles from three sites between 2100 and 2750 m above sea level (masl) show little variation in ion concentrations with altitude, but all sites show strong seasonal variations. Air-mass back trajectories and the identification of storms in snowpits using high-resolution oxygen isotope (δ 18 O) data show that the increases in acid anions in the surface (spring) layers and early-winter snow layers are associated with southwesterly storm systems that swept moisture across the northwestern US into western Canada. July rainfall ion concentrations were 1.5–3.0 times higher than winter snowpack concentrations and were also primarily associated with southwesterly storms. The chemical composition of precipitation in this region, and the relative contribution of snow and rain to annual precipitation, suggest that rates of nitrogen (N) deposition in the Canadian Rocky Mountains may be comparable to the US Rocky Mountains where N deposition is altering ecosystem function. These results lend support to increased monitoring of precipitation chemistry in this environmentally sensitive region.

Modeling Cumulative Effects of Wildfire Hazard Policy and Exurban Household Location Choices: An Application of Agent-based Simulations

The flow of amenity-based migrants to fire-prone areas of the US Rocky Mountain West has brought increasing attention to wildfire hazard mitigation management. This paper attempts to build agent-based models which link natural amenity driven exurban growth to wildfire mitigation regimes to provide a framework for assessing cumulative effects of hazard mitigation policy under alternative policy structures. Three simulations were built to demonstrate how agent-based models (ABM) can be used to examine and compare people's choices of residential location in response to natural amenities and wildfire policies. This paper investigates the ways in which policy effects are incorporated dynamically into the land development decision-making process at an individual level in a case study area. Our results show that individual location choices with respect to wildfire risk are sensitive to wildfire mitigation policies.

Influences of 20th‐century warming at the upper tree line contingent on local‐scale interactions: evidence from a latitudinal gradient in the Rocky Mountains, USA

ABSTRACTAims Twentieth‐century climate, the spatial pattern of tree establishment and positive feedback influence upper tree line ecotones. Here, I investigate how these factors interact to gain a more holistic understanding of how broad‐scale abiotic and local‐scale site conditions regulate tree establishment within upper tree line ecotones.Location A latitudinal gradient (c. 35–45° N) in the US Rocky Mountains. Study sites (n= 22) were located in the Bighorn (BH), Medicine Bow (MB), Front Range (FR) and Sangre de Cristo (SDC) mountain ranges.Methods Dendroecological techniques were used to reconstruct tree establishment dates that were compared with 20th‐century climate data using correlation and regime shift analyses. Spatial patterns of tree establishment were analysed by Ripley's K and used to determine local‐scale interactions capable of ameliorating broad‐scale climate inputs through positive feedback.Results Significant correlations (P < 0.01) between tree establishment and climate were confined to the FR, where a positive correlation was found with summer (June–August) and cool season (November–April) temperature range (Tmax−Tmin). These trees were almost exclusively situated in a random spatial pattern. Similar patterns exist in the BH, yet their establishment was contingent on the availability of local shelter in the lee of boulders. Trees in the MB and SDC were primarily clustered in space and had no significant correlations with climate. Considerable lag times exist between regime shift changes in climate towards more favourable growing conditions and corresponding shifts in tree establishment in all mountain ranges except the FR, where synchronous shifts occurred in the early 1950s.Main conclusions These results suggest that the influence of broad‐scale climate on upper tree line dynamics is contingent on the local‐scale spatial patterns of tree establishment and related influences of positive feedback. This research has important implications for understanding how vegetation communities will respond to global climate change.

Energy Development in the US Rockies: A Role for Counties?

This article analyzes the role played by county commissioners in Colorado and Montana in restricting or facilitating the use of clean energy sources in the generation of electrical power. Using data obtained from responses to an internet survey, we found that many commissioners in both states developed land use policies dealing with renewable energy resources over the preceding five years. Colorado and Montana officials were quite similar in terms of their positive reaction to changes that would facilitate greater county interest in clean energy policies. Most respondents favored increasing the pace of renewable energy use in relation to traditional energy sources but were also supportive of a more inclusive renewable portfolio standard that would embrace clean coal technologies and nuclear power.

Techbits: Hydraulic Fracturing Potential, Challenges Highlighted in Conference

Techbits A distinguished panel of operating company representatives assembled earlier this year to share their views on how hydraulic fracturing is being applied today, and what challenges must be overcome to achieve further gains. The panelists took part in the plenary session "Hydraulic Fracturing: Think Global But Act Local" at the SPE Hydraulic Fracturing Technology Conference 2009 in The Woodlands, Texas. Stephen Holditch, Department Head and Samuel Roberts Noble Foundation-endowed Chair in Petroleum Engineering at Texas A&M University, moderated the plenary. He opened with a discussion of the so-called "resource triangle" theory that states that hydrocarbon resources are distributed log-normally in nature, with easily developed conventional reserves—which are a relatively small portion of overall volume—located at the top of the triangle. "As you get deeper into the resource triangle [closer to the base], the amount of unconventional resource plays is tremendous," Holditch said. A method developed at A&M to evaluate the ratio of conventional to unconventional resources in a basin suggests that there is approximately 10 times more technically recoverable oil and gas from unconventional resources than from conventional reserves. This method was developed from data-rich basins in the US Rockies region, but Holditch is confident that this same ratio should be found in basins around the world. "We are looking at more basins with this technique, and if the 10-to-1 [unconventional to conventional] ratio holds up, this means there is an enormous amount of unconventional resources yet to be produced around the world," he said. "Technology transfer on techniques such as hydraulic fracturing will be key to unlocking these resources." Kirk Bartko, Senior Petroleum Engineering Consultant with Saudi Aramco's Petroleum Engineering Support Division, spoke next about his company's stimulation efforts in Saudi Arabia. He said that as of 2006, the country had more than 5% of the world's known gas reserves with 230 Tcf. "Domestic demand is 7 Bcf per day, and by 2025 this is expected to grow to 14 Bcf per day due to increasing industrial requirements and electricity generation," he continued.

Linear forest patterns in subalpine environments

Studies of feedback between ecological pattern and process can benefit from the analysis of visually striking patterns, as they may reveal underlying processes and clarify the relative role of exogenous versus endogenous factors in driving vegetation change. Roughly linear forest patches are common in subalpine environments, including `hedges', `ribbon forest', and `Shimagare' or `wave regenerated forests' (waves). The influence of wind is common among these patterns, but the role of positive feedback, the most important component of self-organization in biological systems, varies. Hedges are orientated parallel to prevailing winds in several mid-latitude mountain ranges worldwide. Desiccation and ice-particle abrasion kills windward foliage while the vegetation shelters leeward seedlings and growth, so that the patches migrate slowly across the slope. Ribbon forest consists of strips orientated perpendicular to prevailing winds. They have been examined only in the US Rocky Mountains and are the least studied and understood of these phenomena. There are at least three distinct types of ribbon forest, which appear to develop in different ways. Waves are migrating strips of mortality and regeneration orientated perpendicular to prevailing winds in the USA, Japan and Argentina, and dominant controls vary by site. Hedges and waves can develop endogenously with a constant wind, and so can be considered self-organizing in the sense that feedback at the scale of individual trees creates a pattern across the scale of many trees without exogenous forcing. Most ribbon forests seem to be dominated by exogenous forces, but more work is needed to fully characterize the different types.

Breeding biologies, seed production and species‐rich bee guilds of Cleome lutea and Cleome serrulata (Cleomaceae)

AbstractThe summer‐blooming annual forbs Cleome lutea and Cleome serrulata (Cleomaceae) are native across the US Intermountain West and Rocky Mountains, respectively. Their farmed seed is sought to help rehabilitate western rangelands in those regions. This study of the reproductive biologies and pollinator faunas of C. lutea and C. serrulata is the first for this cosmopolitan family, the sister family to the Brassicaceae. Unlike the S‐allele self‐incompatibility systems of some Brassicaceae, both species of Cleome were found to be self‐fertile and capable of some autogamy. Compared with selfing, outcrossing did not enhance seed set, seed viability or seedling vigor for either species (in fact, selfed progeny were more robust). Large, openly visited plants yielded >20 000 seeds each. Like several species of the sister family Capparaceae, flowers of both species first shed their pollen, secreted nectar and became receptive nocturnally. Although no nocturnal visitors were found, both Cleome species attracted a diverse array of diurnal native bees, wasps and butterflies. Among the many floral generalist bees that work Cleome flowers for pollen and nectar are two managed agricultural pollinators, Apis mellifera and Megachile rotundata. These observations bode well for pollinating C. lutea and C. serrulata in small commercial seed fields. It appears that diverse wild bees would benefit from the addition of native Cleome to restoration seed mixes, with the objective of sustaining native pollinator faunas during the first few years of postfire plant community rehabilitation.

Population Growth of Yellowstone Grizzly Bears: Uncertainty and Future Monitoring

Grizzly bears (Ursus arctos) in the Greater Yellowstone Ecosystem of the US Rocky Mountains have recently increased in numbers, but remain vulnerable due to isolation from other populations and predicted reductions in favored food resources. Harris et al. (2006) projected how this population might fare in the future under alternative survival rates, and in doing so estimated the rate of population growth, 1983–2002. We address issues that remain from that earlier work: (1) the degree of uncertainty surrounding our estimates of the rate of population change (λ); (2) the effect of correlation among demographic parameters on these estimates; and (3) how a future monitoring system using counts of females accompanied by cubs might usefully differentiate between short-term, expected, and inconsequential fluctuations versus a true change in system state. We used Monte Carlo re-sampling of beta distributions derived from the demographic parameters used by Harris et al. (2006) to derive distributions of λ during 1983–2002 given our sampling uncertainty. Approximate 95% confidence intervals were 0.972–1.096 (assuming females with unresolved fates died) and 1.008–1.115 (with unresolved females censored at last contact). We used well-supported models of Haroldson et al. (2006) and Schwartz et al. (2006a,b,c) to assess the strength of correlations among demographic processes and the effect of omitting them in projection models. Incorporating correlations among demographic parameters yielded point estimates of λ that were nearly identical to those from the earlier model that omitted correlations, but yielded wider confidence intervals surrounding λ. Finally, we suggest that fitting linear and quadratic curves to the trend suggested by the estimated number of females with cubs in the ecosystem, and using AICc model weights to infer population sizes and λ provides an objective means to monitoring approximate population trajectories in addition to demographic analysis.

Fire, fuels and restoration of ponderosa pine–Douglas fir forests in the Rocky Mountains, USA

AbstractAim Forest restoration in ponderosa pine and mixed ponderosa pine–Douglas fir forests in the US Rocky Mountains has been highly influenced by a historical model of frequent, low‐severity surface fires developed for the ponderosa pine forests of the Southwestern USA. A restoration model, based on this low‐severity fire model, focuses on thinning and prescribed burning to restore historical forest structure. However, in the US Rocky Mountains, research on fire history and forest structure, and early historical reports, suggest the low‐severity model may only apply in limited geographical areas. The aim of this article is to elaborate a new variable‐severity fire model and evaluate the applicability of this model, along with the low‐severity model, for the ponderosa pine–Douglas fir forests of the Rocky Mountains.Location Rocky Mountains, USA.Methods The geographical applicability of the two fire models is evaluated using historical records, fire histories and forest age‐structure analyses.Results Historical sources and tree‐ring reconstructions document that, near or before ad 1900, the low‐severity model may apply in dry, low‐elevation settings, but that fires naturally varied in severity in most of these forests. Low‐severity fires were common, but high‐severity fires also burned thousands of hectares. Tree regeneration increased after these high‐severity fires, and often attained densities much greater than those reconstructed for Southwestern ponderosa pine forests.Main conclusions Exclusion of fire has not clearly and uniformly increased fuels or shifted the fire type from low‐ to high‐severity fires. However, logging and livestock grazing have increased tree densities and risk of high‐severity fires in some areas. Restoration is likely to be most effective which seeks to (1) restore variability of fire, (2) reverse changes brought about by livestock grazing and logging, and (3) modify these land uses so that degradation is not repeated.

Spatiotemporal variability in stream chemistry in a high-elevation catchment affected by mine drainage

This study examined solute dynamics on both spatial and temporal (seasonal, 24 h) scales in a high-elevation stream affected by drainage from abandoned metal mines. Peru Creek is located along the Continental Divide in the US Rocky Mountains, and the hydrologic cycle is dominated by melting of snow. Spatially, tributary inflows produced order-of-magnitude concentration changes along Peru Creek; these were due to dilution and concentration, and also to precipitation of solids. Seasonally, the concentration of most solutes increased as snowmelt diminished. Concentrations of Al, Fe, Cu and Zn, at times affected by instream processes, increased the most, by factors of 2.1–12.8. Ca, Mg, and SO 4 2−, which approximated conservative behavior, increased by factors of 1.7–2.2. Si, Na and K, which were unaffected by mine drainage, increased less, by factors of 1.1–1.6. Concentrations of NO 3 − decreased slightly during the snowmelt season. Hydrologic, photochemical and biological processes were active on the 24 h timescale and produced daily concentration variations of up to 40%. Accurate predictions of solute concentrations, which rely on knowledge of processes that produce natural cycling, are crucial in developing models of toxicity and pollutant loading.

Fire History in Interior Ponderosa Pine Communities of the Black Hills, South Dakota, USA

Chronologies of fire events were reconstructed from crossdated fire-scarred ponderosa pine trees for four sites in the south-central Black Hills. Compared to other ponderosa pine forests in the southwest US or southern Rocky Mountains, these communities burned less frequently. For all sites combined, and using all fires detected, the mean fire interval (MFI), or number of years between fire years, was 16 years (± 14 SD) for the period 1388 to 1900. When a yearly minimum percentage of trees recording scars of ≥ 25% is imposed, the MFI was 20 years (± 14 SD). The length of the most recent fire-free period (104 years, from 1890 to 1994) exceeds the longest intervals in the pre-settlement era (before ca. 1874), and is likely the result of human-induced land use changes. Based on fire scar position within annual rings, most past fires occurred late in the growing season or after growth had ceased for the year. These findings have important implications for management of ponderosa pine forests in the Black Hills and for understanding the role of fire in pre-settlement ecosystem function.

The effects of aggregating sub-grid land surface variation on large-scale estimates of net primary production

The use of large grid cell databases (1/2° to 5°) to drive nonlinear ecosystem process models may create an incompatibility of scales which can often lead to biased outputs. Global simulations of net primary production (NPP) often assume that bias due to averaging of sub-grid variations in climate, topography, soils, and vegetation is minimal, yet the magnitude and behavior of this bias on estimates of NPP are largely unknown. The effects of averaging sub-grid land surface variations on NPP estimates were evaluated by simulating a 1° × 1° land surface area as represented by four successive levels of landscape complexity, ranging from a single computation to 8,456 computations of NPP for the study area. Averaging sub-grid cell landscape variations typical of the northern US Rocky Mountains can result in overestimates of NPP as large as 30 %. Aggregating climate within the 1° cell contributed up to 50 % of the bias to NPP estimates, while aggregating topography, soils, and vegetation was of secondary importance. Careful partitioning of complex landscapes can efficiently reduce the magnitude of this overestimation.

Correlations between pyrolysis mass spectra of Rocky Mountain coals and conventional coal parameters

Correlations between Curie-point pyrolysis m.s. data on 102 coal samples from the US Rocky Mountain coal province and a set of 25 conventional parameters, including ultimate, proximate, petrographic and mineralogic measurements, obtained from the Penn State Coal Data Bank were investigated using computerized multivariate statistical analysis techniques. Strong correlations were found between both data sets with regard to rank-related parameters as well as sulphur parameters, whereas moderately strong correlations exist with regard to petrographic and mineralogical parameters as well as nitrogen content. Independent factor analysis of both data matrices provides factor score plots showing remarkably similar relations between samples from different coal regions, fields and seams. In fact, up to 80% of common variance is found in the conventional and pyrolysis m.s. data sets. The large proportion of variance common to both data sets permits the calculation of numerical models which enable direct prediction of technologically important parameters such as rank, calorific value and, possibly, aromaticity from pyrolysis m.s. patterns.