2011 monitoring and tracking wet nitrogen deposition at Rocky Mountain National Park
No abstract available.
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Geology topics
Research about Rocky Mountain National Park
Source-linked reports with geographic coverage including Rocky Mountain National Park.
Evaluation of National Atmospheric Deposition Program measurements for co-located Sites CO89 and CO98 at Rocky Mountain National Park, 2012
Atmospheric wet-deposition monitoring in Rocky Mountain National Park included precipitation depth and aqueous chemical measurements at co-located National Atmospheric Deposition Program (NADP) sites CO89 and CO98 (Loch Vale) during 2012. The co-located sites are separated by approximately 6.5 meters horizontally and 0.5 meters in altitude, which meets NADP siting criteria. Median weekly absolute percent differences for selected parameters including: sample volume, 8.0 percent; ammonium concentration, 9.1 percent; nitrate concentration, 8.5 percent; sulfate concentration, 10.2 percent. Annual precipitation-weighted mean concentrations were higher for CO98 compared to CO89 for all analytes. The chemical concentration record for CO98 contains more valid samples than the CO89 record. Therefore, the CO98 record is more representative of 2012 total annual deposition at Loch Vale. Daily precipitation-depth records for the co-located precipitation gages were 100 percent complete, and the total annual precipitation depths between the sites differed by 0.1 percent for the year (91.5 and 91.4 cm).
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The genetic structure of a relict population of wood frogs
Habitat fragmentation and the associated reduction in connectivity between habitat patches are commonly cited causes of genetic differentiation and reduced genetic variation in animal populations. We used eight microsatellite markers to investigate genetic structure and levels of genetic diversity in a relict population of wood frogs ( Lithobates sylvatica ) in Rocky Mountain National Park, Colorado, where recent disturbances have altered hydrologic processes and fragmented amphibian habitat. We also estimated migration rates among subpopulations, tested for a pattern of isolation-by-distance, and looked for evidence of a recent population bottleneck. The results from the clustering algorithm in Program STRUCTURE indicated the population is partitioned into two genetic clusters (subpopulations), and this result was further supported by factorial component analysis. In addition, an estimate of FST (FST = 0.0675, P value \0.0001) supported the genetic differentiation of the two clusters. Estimates of migration rates among the two subpopulations were low, as were estimates of genetic variability. Conservation of the population of wood frogs may be improved by increasing the spatial distribution of the population and improving gene flow between the subpopulations. Construction or restoration of wetlands in the landscape between the clusters has the potential to address each of these objectives.
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The importance of local and landscape-scale processes to the occupancy of wetlands by pond-breeding amphibians
Variation in the distribution and abundance of species across landscapes has traditionally been attributed to processes operating at fine spatial scales (i.e., environmental conditions at the scale of the sampling unit), but processes that operate across larger spatial scales such as seasonal migration or dispersal are also important. To determine the relative importance of these processes, we evaluated hypothesized relationships between the probability of occupancy in wetlands by two amphibians [wood frogs (Lithobates sylvaticus) and boreal chorus frogs (Pseudacris maculata)] and attributes of the landscape measured at three spatial scales in Rocky Mountain National Park, Colorado. We used cost-based buffers and least-cost distances to derive estimates of landscape attributes that may affect occupancy patterns from the broader spatial scales. The most highly ranked models provide strong support for a positive relationship between occupancy by breeding wood frogs and the amount of streamside habitat adjacent to a wetland. The model selection results for boreal chorus frogs are highly uncertain, though several of the most highly ranked models indicate a positive association between occupancy and the number of neighboring, occupied wetlands. We found little evidence that occupancy of either species was correlated with local-scale attributes measured at the scale of individual wetlands, suggesting that processes operating at broader scales may be more important in influencing occupancy patterns in amphibian populations.
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Monitoring plan for vegetation responses to elk management in Rocky Mountain National Park
Rocky Mountain National Park (RMNP) in north-central Colorado supports numerous species of wildlife, including several large ungulate species among which Rocky Mountain elk (Cervus elaphus) are the most abundant. Elk are native to RMNP but were extirpated from the area by the late 1800s. They were reintroduced to the area in 1913-1914, and the elk herd grew to the point that it was actively managed from 1944 until 1968. In 1969, the active control of elk was discontinued and since then the herd has increased to a high point ranging from 2,800 to 3,500 between 1997 and 2001. In recent years, there has been growing concern over the condition of vegetation in the park and conflicts between elk and humans, both inside and outside the park. In response to these concerns, RMNP implemented an Elk and Vegetation Management Plan (EVMP) in 2009 to guide management actions in the park over a 20-year time period with the goal of reducing the impacts of elk on vegetation and restoring the natural range of variability in the elk population and affected plant and animal communities. The EVMP outlines the desired future condition for three vegetation communities where the majority of elk herbivory impacts are being observed: aspen, montane riparian willow, and upland herbaceous communities. The EVMP incorporates the principle of adaptive management whereby the effectiveness of management actions is assessed and adjusted as needed to successfully achieve objectives. Determination of whether vegetation objectives are being achieved requires monitoring and evaluation of target vegetation communities. The current report describes the design and implementation of a vegetation-monitoring program to help RMNP managers assess the effectiveness of their management actions and determine when and where to alter actions to achieve the EVMP's vegetation objectives. This monitoring plan details the process of selecting variables to be monitored, overall sampling design and structure, site selection, data collection methods, and statistical analyses to be used to conduct this monitoring program in conjunction with the EVMP. We report the baseline conditions observed at the time of the establishment of monitoring sites. We include detailed field protocols for site establishment and data collection, as well as timetables for sampling, so that RMNP staff will be able to continue monitoring the sites established during this implementation stage, and continue to add new sites when necessary, as the execution of the EVMP proceeds over the next 20 years.
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Chemical weathering in the Loch Vale Watershed, Rocky Mountain National Park, Colorado
Mineralogic, hydrologic, and geochemical data were used to determine the source of solutes to surface waters draining the Loch Vale Watershed (LVWS), an alpine-subalpine drainage located in the Front Range of Colorado. The flux of dissolved solids from LVWS is primarily controlled by interactions between snowmelt and materials derived from the local bedrock; the biomass has only a minor effect on solute budgets except for ammonium. LVWS is underlain by Precambrian granite and gneiss, the major minerals include quartz, microcline, plagioclase, biotite, and sillimanite. Small amounts of calcite were found along hydrothermally altered zones in the bedrock. Mass balance calculations indicate that the weathering of calcite contributes nearly 40% of the cations derived within the basin. The importance of calcite weathering in LVWS is a result of its chemical reactivity and the high rate of physical erosion in this alpine environment. The average cationic denudation rate in the drainage (390 eq/ha/yr) is similar to long-term rates in forested Adirondack watersheds (500–600 eq/ha/yr), but much lower than the average for the North American Continent (3800 eq/ha/yr). Surface waters in LVWS are susceptible to acidification should acid deposition from the atmosphere increase.
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Species-area curves indicate the importance of habitats' contributions to regional biodiversity
We examined species-area curves, species composition and similarity (Jaccard's coefficients), and species richness in 17 vegetation types to develop a composite index of a vegetation type's contribution to regional species richness. We collected data from 1 to 1000 m2 scales in 147 nested plots in Rocky Mountain National Park, Colorado, USA to compare three species-area curve models' abilities to estimate the number of species observed in each vegetation type. The log(species)-log(area) curve had the largest adjusted coefficients of determination (r2 values) in 12 of the 17 types, followed by the species-log(area) curve with five of the highest values. When the slopes of the curves were corrected for species overlap among plots with Jaccard's coefficients, the species-log(area) curves estimated values closest to those observed. We combined information from species-area curves and measures of heterogeneity with information on the area covered by each vegetation type and found that the types making the greatest contributions to regional biodiversity covered the smallest areas. This approach may provide an accurate and relatively rapid way to rank hotspots of plant diversity within regions of interest.
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Estimation of temporary emigration in male toads
Male boreal toads (Bufo boreas) are thought to return to the breeding site every year but, if absent in a particular year, will be more likely to return the following year. Using Pollock's robust design we estimated temporary emigration (the probability a male toad is absent from a breeding site in a given year) at three locations in Colorado, USA: two in Rocky Mountain National Park and one in Chaffee County. We present data that suggest that not all male toads return to the breeding site every year. Our analyses indicate that temporary emigration varies by site and time (for example, from 1992 to 1998, the probability of temporary emigration ranged from 10% to 29% and from 3% to 95% at Lost Lake and Kettle Tarn, respectively). Although the results provide weak evidence that males are more likely to return after a year's hiatus, a general pattern of state-dependent temporary emigration was not supported. We also hypothesized relationships between temporary emigration and a number of weather variables. While some competitive models included weather covariates, imprecise and variable estimates of the effects of these covariates precluded fully defining their impact on temporary emigration. ?? 2006 by the Ecological Society of America.
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Alpine plant community trends on the elk summer range of Rocky Mountain National Park, Colorado: An analysis of existing data
The majority of the elk (Cervus elaphus) population of Rocky Mountain National Park in Colorado summer in the park’s high-elevation alpine and subalpine meadows and willow krummholz. The park’s population of white-tailed ptarmigan (Lagopus leucurus altipetens) depends on both dwarf and krummholz willows for food and cover. Concern about the effects of elk herbivory on these communities prompted the monitoring of 12 vegetation transects in these regions from 1971 to 1996. Over this 25-year period, data were collected on plant species cover and frequency and shrub heights. These data have not been statistically analyzed for trends in the measured variables over time to determine changes in species abundance. Krummholz willow species (Salix planifolia, S. brachycarpa) declined 17–20 percent in cover and about 25 centimeters in height over the study period. Graminoids (particularly Deschampsia caespitosa, Carex, and Poa) increased slightly from 1971 to 1996. No significant increases of nonnative plant species were observed. An increase in presence of bare ground over the 25-year period warrants continued measurement of these transects. Lack of good data on elk density, distribution, or use levels precludes correlating changes in plant species cover, frequency, or heights with elk population trends. I recommend development of a more rigorously designed monitoring program that includes these transects as well as others chosen on a random or stratified design and consistent measurement protocol and sampling intervals. Some method of quantifying elk use, either through measurement of plant utilization, pellet counts, or census-type surveys, would allow correlation of changes in plant species over time with changes in elk distribution and density on the park’s alpine and subalpine regions.
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Mercury transport in a high-elevation watershed in Rocky Mountain National Park, Colorado
Mercury (Hg) was measured in stream water and precipitation in the Loch Vale watershed in Rocky Mountain National Park, Colorado, during 2001–2002 to investigate processes controlling Hg transport in high-elevation ecosystems. Total Hg concentrations in precipitation ranged from 2.6 to 36.2 ng/L and showed a strong seasonal pattern with concentrations that were 3 to 4 times higher during summer months. Annual bulk deposition of Hg was 8.3 to 12.4 μ g/m 2 and was similar to deposition rates in the Midwestern and Northeastern U.S. Total Hg concentrations in streams ranged from 0.8 to 13.5 ng/L and were highest in mid-May on the rising limb of the snowmelt hydrograph. Stream-water Hg was positively correlated with dissolved organic carbon suggesting organically complexed Hg was flushed into streams from near-surface soil horizons during the early stages of snowmelt. Methylmercury (MeHg) in stream water peaked at 0.048 ng/L just prior to peak snowmelt but was at or below detection (< 0.040 ng/L) for the remainder of the snowmelt season. Annual export of total Hg in Loch Vale streams ranged from 1.2 to 2.3 μ g/m 2 , which was less than 20% of wet deposition, indicating the terrestrial environment is a net sink of atmospheric Hg. Concentrations of MeHg in stream water and corresponding watershed fluxes were low, indicating low methylation rates or high demethylation rates or both.
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Effects of conifers and elk browsing on quaking aspen forests in the central Rocky Mountains, USA
Elk browsing and conifer species mixing with aspen ( Populus tremuloides Michx.) present current challenges to aspen forest management in the western United States. We evaluated the effects of conifers and elk browsing on quaking aspen stands in and near Rocky Mountain National Park using tree rings to reconstruct patterns of aspen establishment, growth, and mortality over the past 120 years. High conifer encroachment and elk browse were both associated with decreased aspen recruitment, with mean recruitment dropping over 30% from pure aspen to mixed stands and over 50% from low-browse to high-browse stands. Maximum aspen recruitment was lower in mixed stands than in pure stands with the same tree basal area. High levels of elk browsing were also associated with a 30% decrease in stand-level growth of aspen. Neither high conifer abundance nor elk browse affected the growth of individual trees or aspen mortality. Aspen establishment was negatively influenced by conifers and elk browsing; however, aspen growth and mortality appeared to be resilient to these two external influences. Overall, these results suggest that long-term preservation of aspen forests could be achieved by enhancing aspen recruitment.
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Effects of elk herbivory on vegetation and nitrogen processes
We used 35-year and 4-year ungulate exclosures to determine the effects of elk ( Cervus elaphus ) herbivory on above-ground and below-ground production and soil fertility on the elk winter range in Rocky Mountain National Park (RMNP), Colorado, USA. We used paired grazed and ungrazed plots to evaluate ungulate herbivory effects in short and tall willow ( Salix spp.), aspen ( Populus spp.), and upland grass/shrub vegetation associations. We measured nitrogen (N) fluxes (litter deposition, fecal and urinary deposition from elk, movements of N by elk, N mineralization, soil N availability, elk consumption rates) within the elk winter, above-ground and below-ground N pools (herbaceous, shrub and root biomass, %N in plants, roots, and soil), and N fluxes on and off the elk winter range (seasonal movement of N by elk). Nitrogen mineralization and soil nitrate (NO 3 ) pools were reduced in the short willow community ( P = 0.07 and 0.10, respectively; n = 4 sites) in grazed plots, but not in the upland grass/shrub community or tall willow sites ( P >0.10). Annual growth of willows was reduced by 98% in grazed plots, relative to 35-year exclosures, and 66% relative to 4-year exclosures. Thus, height, canopy size, and litter biomass of willows were reduced, and N yield of willows was 64% less in grazed plots. We evaluated movement of N by elk among 6 major vegetation associations and found that elk grazed more and bedded less in willow vegetation association compared to mixed conifer, mesic meadow, and grassland/shrub associations ( P = 0.014, 0.001, and 0.026, respectively), suggesting that elk herbivory and movement led to a net loss of N in the willow vegetation association. Elk spent less total time in willows than mesic meadow association, yet they consumed large amounts of willow plant biomass. We recommend management of elk numbers and elk herbivory that takes into consideration impacts to N process function, as negative effects from current levels of herbivory were observed in ≥1 of 3 vegetation associations studied.
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Recent ecological and biogeochemical changes in alpine lakes of Rocky Mountain National Park (Colorado, USA): A response to anthropogenic nitrogen deposition
Dated sediment cores from five alpine lakes (>3200 m asl) in Rocky Mountain National Park (Colorado Front Range, USA) record near-synchronous stratigraphic changes that are believed to reflect ecological and biogeochemical responses to enhanced nitrogen deposition from anthropogenic sources. Changes in sediment proxies include progressive increases in the frequencies of mesotrophic planktonic diatom taxa and diatom concentrations, coupled with depletions of sediment δ 15 N and C : N values. These trends are especially pronounced since approximately 1950. The most conspicuous diatoms to expand in recent decades are Asterionella formosa and Fragilaria crotonensis . Down-core species changes are corroborated by a year-long sediment trap experiment from one of the lakes, which reveals high frequencies of these two taxa during autumn and winter months, the interval of peak annual limnetic [NO 3 - ]. Although all lakes record recent changes, the amplitude of stratigraphic shifts is greater in lakes east of the Continental Divide relative to those on the western slope, implying that most nitrogen enrichment originates from urban, industrial and agricultural sources east of the Rocky Mountains. Deviations from natural trajectories of lake ontogeny are illustrated by canonical correspondence analysis, which constrains the diatom record as a response to changes in nitrogen biogeochemistry. These results indicate that modest rates of anthropogenic nitrogen deposition are fully capable of inducing directional biological and biogeochemical shifts in relatively pristine ecosystems.
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Wilderness experience in Rocky Mountain National Park 2002; report to respondents
A substantial amount of backcountry (about 250,000 acres) in Rocky Mountain National Park [RMNP of the Park] may be designated as wilderness areas in the coming years. Currently, over 3 million visitors drives through the park on Trail Ridge Road, camp in designated campgrounds, day hike, etc. each year. Many of those visitors also report using the backcountry-wilderness areas that are not easily accessible by roads or trails. Use of the backcountry is growing at RMNP and is accompanied by changing visitor expectations and preferences for wilderness management. For these reasons it is of great importance for the Park to periodically assess what types of environments and conditions wilderness users seek to facilitate a quality experience. To assist in this effort, the Political Analysis and Science Assistance [PSAS] program / Fort Collins Center / U.S. Geological Survey, in close collaboration with personnel and volunteers from RMNP, as well as the Natural Resource Recreation and Tourism [NRRT] Department at Colorado State University, launched a research effort in the summer of 2002 to investigate visitors wilderness experiences in the Park. Specifically, the purpose of this research was: (1) To determine what constitutes a wilderness experience; (2) To identify important places, visual features, and sounds essential to a quality wilderness experience and; (3) To determine what aspects may detract from wilderness experience. Thus, answers to these questions should provide insight for Park managers about visitors expectation for wilderness recreation and the conditions they seek for quality wilderness experiences. Ultimately, this information can be used to support wilderness management decisions within RMNP. The social science technique of Visitor Employed Photography [VEP] was used to obtain information from visitors about wilderness experiences. Visitors were selected at random from Park-designated wilderness trails, in proportion to their use, and asked to participate in the survey. Respondents were given single use, 10-exposure cameras and photo-log diaries to record experiences. A total of 293 cameras were distributed, with a response rate of 87%. Following the development of the photos, a copy of the photos, two pertinent pages from the photo-log, and a follow-up survey were mailed to respondents. Fifty-six percent of the follow-up surveys were returned. Findings from the two surveys were analyzed and compared.
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Atmospheric deposition of nutrients, pesticides, and mercury in Rocky Mountain National Park, Colorado, 2002
Nutrients, current-use pesticides, and mercury were measured in atmospheric deposition during summer in Rocky Mountain National Park in Colorado to improve understanding of the type and magnitude of atmospheric contaminants being deposited in the park. Two deposition sites were established on the east side of the park: one at an elevation of 2,902 meters near Bear Lake for nutrients and pesticides, and one at an elevation of 3,159 meters in the Loch Vale watershed for mercury. Concentrations of nutrients in summer precipitation at Bear Lake ranged from less than 0.007 to 1.29 mg N/L (milligrams of nitrogen per liter) for ammonium and 0.17 to 4.59 mg N/L for nitrate and were similar to those measured at the Loch Vale National Atmospheric Deposition Network station, where nitrogen concentrations in precipitation are among the highest in the Rocky Mountains. Atrazine, dacthal, and carbaryl were the most frequently detected pesticides at Bear Lake, with carbaryl present at the highest concentrations (0.0079 to 0.0952 ?g/L (micrograms per liter), followed by atrazine (less than 0.0070 to 0.0604 ?g/L), and dacthal (0.0030 to 0.0093 ?g/L). Mercury was detected in weekly bulk deposition samples from Loch Vale in concentrations ranging from 2.6 to 36.2 ng/L (nanograms per liter). Concentrations in summer precipitation were combined with snowpack data from a separate study to estimate annual deposition rates of these contaminants in 2002. Annual bulk nitrogen deposition in 2002 was 2.28 kg N/ha (kilograms of nitrogen per hectare) at Bear Lake and 3.35 kg N/ha at Loch Vale. Comparison of wet and bulk deposition indicated that dry deposition may account for as much as 28 percent of annual nitrogen deposition, most of which was deposited during the summer months. Annual deposition rates for three pesticides were estimated as 45.8 mg/ha (milligrams per hectare) of atrazine, 14.2 mg/ha of dacthal, and 54.8 mg/ha of carbaryl. Because of much higher pesticide concentrations in summer precipitation than in winter snow, between 80 to 90 percent of the annual pesticide deposition occurs during summer. Mercury deposition to Loch Vale was estimated at 7.1 ?g/m2 (micrograms per square meter) of which nearly 70 percent of the annual mercury deposition occurred during summer. Despite the fact that most precipitation at high-elevations falls during winter, these results emphasize the importance of monitoring precipitation chemistry during summer to improve estimates of contaminant deposition to high-elevation ecosystems in Rocky Mountain National Park. Air-parcel back trajectories were calculated using an atmospheric transport model to identify potential source regions for contaminants reaching the park. The results indicate that during the winter, the most likely source of contami-nants is from areas northwest of the park, but during summer, contaminants are most likely coming from sources to the southwest and east.
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Beaver (Castor canadensis) in heavily browsed environments
Beaver ( Castor canadensis ) populations have declined or failed to recover in heavily browsed environments. I suggest that intense browsing by livestock or ungulates can disrupt beaver-willow ( Salix spp.) mutualisms that likely evolved under relatively low herbivory in a more predator-rich environment, and that this interaction may explain beaver and willow declines. Field experiments in Rocky Mountain National Park, Colorado, USA, found the interaction of beaver and elk ( Cervus elaphus ) herbivory suppressed compensatory growth in willow. Intense elk browsing of simulated beaver-cut willow produced plants which were small and hedged with a high percentage of dead stems, whereas protected plants were large and highly branched with a low percentage of dead stems. Evaluation of a winter food cache showed beaver had selected woody stems with a lower percentage of leaders browsed by elk. A lack of willow stems suitable as winter beaver food may cause beaver populations to decline, creating a negative feedback mechanism for beaver and willow. In contrast, if browsing by livestock or ungulates can be controlled, and beaver can disperse from a nearby source population, then beaver may build dams in marginal habitat which will benefit willow and cause a positive riparian response that restores proper function to degraded habitat. In a shrub-steppe riparian ecosystem of northwestern Colorado, USA, rest from overgrazing of livestock released herbaceous vegetation initiating restoration of a beaver-willow community. Thus, competition from livestock or ungulates can cause beaver and willow to decline and can prevent their restoration in heavily browsed riparian environments, but beaver and willow populations can recover under proper grazing management.
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Influences of herbivory and water on willow in elk winter range
Elimination of large predators and reduced hunter harvest have led to concerns that an increasing elk ( Cervus elaphus ) population may be adversely affecting vegetation on the low-elevation elk winter range of Rocky Mountain National Park, Colorado, USA. Beaver ( Castor canadensis ) and their impoundments also have declined dramatically (94%) in the same area over the past 50 years coincident with a 20% decline in willow ( Salix spp.) cover. From 1994 to 1998, we studied vegetation production responses of willow communities to elk herbivory and water availability. We estimated willow production by measuring current annual growth of shrubs in 9.3-m2 circular plots, and we measured herbaceous production by clipping vegetation within 0.25-m2 circular plots. Elk herbivory suppressed willow heights, leader lengths, annual production, and herbaceous productivity of willow communities. Water impoundment had a positive effect on herbaceous plant production, but little effect on shrubs, possibly because water tables were naturally high on the study sites even without beaver dams. Nevertheless, the winter range environment previously included more riparian willow habitat because of more stream area (47-69%) due to larger beaver populations. Elk herbivory appears to be the dominant force determining vegetation productivity in willow sites, but the effects may be exacerbated by lowered water tables. Fewer elk or protection from browsing, and water enhancement for <10 years along with management to encourage elk movement away from willow communities, could possibly work as strategies to reestablish sustainable willow communities.
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Ecological evaluation of the abundance and effects of elk herbivory in Rocky Mountain National Park, Colorado, 1994-1999
Several National Park Service units in the Intermountain region possess a number of closely related management needs relative to the abundance of wild ungulates and their herbivory effects on plants and ecosystem processes. In 1993, the then National Biological Service (NBS) - now U.S. Geological Survey, Biological Resources Discipline (USGS, BRD) initiated a series of research studies in four park units in the Intermountain West., into the abundance and effects of ungulates on park ecosystems. Each of these parks received a number of similar research study elements including: (a) a number of new ungulate grazing exclosures (n = 12-21 exclosures per park); (b) aerial survey sightability models to estimate population sizes of ungulates; (e) measures of biomass production and consumption rates near the exclosures and across the landscape; (d) studies of the effects of the grazing on plant abundance, species diversity, and ecosystem effects; and (e) computer model simulations (SAVANNA) of the effects on the ecosystem and plant resources of different ungulate management scenarios. One park unit, Rocky Mountain National Park, Colorado, received funding from the U.S. Geological Survey (USGS, BRD) and parallel funding from NPS for an intensive research study of the effects of elk on the park ecosystems.
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