Rocky Mountain National Park Research Articles

Regulating overabundant ungulate populations: An example for elk in Rocky Mountain National Park, Colorado

In many areas of the world, populations of native ungulates have become so abundant that they are believed to be harming vegetation and disrupting ecosystem function. Methods for controlling overabundance populations include culling animals from the population and controlling fertility using contraceptives. However, understanding the feasibility these alternatives requires insight into their long-term effects on populations. We constructed a simulation model to evaluate options for regulating elk populations in and around Rocky Mountain National Park and used the model to compare different treatment options. Methods were evaulated with respect to the time required to reduce the population to a target level, the number of animals treated and/or culled and the risk of extinction. We contrasted culling with lifetime-effect contraceptives and yearlong contraceptives. Lifetime contraceptives required treating the fewest animals to maintain the population at desired targets. However, this approach also causes the greatest population variability and potential risk of extinction. Yearlong contraceptives required treatment of dramatically more animals but had essentially no extinction risk whereas culling produced intermediate levels of both extinction risk and number of animals treated. These results characterize the risks and benefits of alternative control strategies for overabundant wildlife. They emerge from a modeling approach that can be broadly useful in helping managers in choose between alternatives for regulating overabundant wildlife.

Bighorn Sheep Abundance Following a Suspected Pneumonia Epidemic in Rocky Mountain National Park

Abstract: Anecdotal evidence of a pneumonia epizootic among bighorn sheep (Ovis canadensis canadensis) in Rocky Mountain National Park (RMNP), Colorado, USA, during the mid‐1990s prompted park officials to examine the current condition of the herds. Here we present a mark—resight study design to estimate population abundance that, in many circumstances, is a reliable and cost‐effective alternative to traditional mark—recapture or to indices of population abundance. We captured 59 adult females and radiocollared them via helicopter net‐gunning during winter 2002–2003. From ground resighting surveys conducted May—September, we estimated the total RMNP bighorn population at 389.9 (SE = 34.9, CI = 327.2–464.6) in 2003 and 366.4 (SE = 34.7, CI = 304.4–441.0) in 2004. Previous abundance estimates suggest a park‐wide decline has occurred between the late 1980s and the suspected pneumonia epidemic of the mid‐1990s. Although the 2 years of data from our study are not enough to predict whether the herds are capable of recovering to previous levels, they provide park officials the tools necessary to make the most informed decisions for future monitoring and management of this fragile species.

Natural Regeneration of Alpine Tundra Vegetation after Human Trampling: a 42-year Data Set from Rocky Mountain National Park, Colorado, U.S.A

ABSTRACTThe vegetation composition of four contiguous permanent plots was analyzed during 37 of 42 years between 1959 and 2001 to evaluate successional processes following the cessation of human trampling in alpine tundra. The plots were established adjacent to the Rock Cut parking lot at ~3658 m elevation along Trail Ridge Road in Rocky Mountain National Park, Colorado. Due to limitations in the original study design, the lack of true replication required that the plots be treated individually when subject to indirect ordination analysis to follow trends in overall plant composition and cover. The three most abundant species in the study plots were Artemisia scopulorum, Acomastylis rossii, and Kobresia myosuroides. At the beginning of the study in 1959, total cover ranged from 20 to 55% in the four plots. By 1961, three of the four plots achieved total canopy cover values of at least 100%. Vascular plant species richness (number of taxa per plot) averaged 20 in 1959, but by 1967 had nearly doubled to 37. During the first several years, rates of seedling emergence were high among most taxa with the notable exceptions of K. myosuroides and A. rossii. However, likely due to desiccation and needle ice, seedling mortality was high. K. myosuroides spread exclusively from remnant tufts, as did three species of cushion plants which survived the trampling. The overall decline in plant cover during the last two decades of this study, particularly for K. myosuroides, indicates that long-term unassisted regeneration of severely degraded alpine tundra sites will take more than a century. While there have been periods of plant colonization and spread, climate factors such as a series of heavy snow years, and unchecked soil erosion from trails, can limit plant establishment and stop the recovery process, or push the recovery back by several decades. The negative influence of soil erosion, and quite possibly additional trampling, over a significant portion of the study plot points to the critical importance of using extreme care when establishing long-term monitoring plots, particularly in high-use areas.

America's Switzerland: Estes Park and Rocky Mountain National Park, the Growth Years

America's Switzerland: Estes Park and Rocky Mountain National Park, the Growth Years

Spatial and temporal variations in bed load transport intensity in a gravel bed river bend

Variability in bed load sediment transport is investigated for a bend of the Colorado River in Rocky Mountain National Park. Data from 190 bed load samples taken at 50 to 125% bankfull flow at a large number of locations throughout the reach indicate that the fine and coarse fractions of the load are differentially routed, such that fine grains are swept inward over the point bar, while coarse grains are routed outward toward the pool. At bankfull flow, all size fractions of the available sediment are transported throughout the bend, but the median grain size of the bed load increases with distance toward the outer bank. This differential routing decreases slightly with increasing discharge beyond bankfull, as indicated by a shift in the locus of coarse particle transport from the outside of the bend inward to the channel center. Furthermore, while fine sediments are fully mobile throughout the bend, partial mobility of the coarse fractions of the load transitions to full mobility toward the bend's outer region. These patterns are flow dependent; with increasing discharge the distribution of excess Shields stress becomes more uniform, resulting in reduced variability in bed load transport rates across the channel. These variations in transport intensity lead to a volumetric balance of transported sediment between the inner and outer regions of the channel, which thereby promotes the geomorphic stability of the bend.

YMCA Hiking Patterns at Rocky Mountain National Park: Implications for Public Health

There is little data on hiking patterns in national parks to support hiking behavior as a vehicle to meet the joint YMCA, CDC, and National Park Service initiatives to encourage physical activity through public land use. The YMCA of the Rockies hiking program provided data from Hike Report forms completed after 343 supervised hikes for one summer season in Rocky Mountain National Park (ROMO) to assess visitor hiking patterns. Of the total hikes, 64.4% were categorized as easy, 27.1% moderate, and 8.5% difficult. There were 1937 individual hikers which represented 13.3% of the estimated potential hiker sample. The majority of hikers (69%) only took easy hikes with 72.7% participating in only one hike and 27.3% doing two or more hikes. Energy cost estimates for hike categories indicated mean MET levels between 4.0 to 5.7. Hiking patterns at ROMO may be reflective of general population inactivity suggesting the need to design strategies to promote visitor hiking.

20th-century variations in area of cirque glaciers and glacierets, Rocky Mountain National Park, Rocky Mountains, Colorado, USA

AbstractComparison of historic maps and aerial and ground-based photographs for the small cirque glaciers and glacierets of Rocky Mountain National Park in the northern Front Range of Colorado, USA, indicates modest change during the 20th century. The glaciers retreated through the first half of the 20th century, advanced slightly from the mid-1940s to the end of the century and have retreated slightly since. High interannual variability in area and temporal gaps in data complicate the trends. Local climate records indicate a lack of systematic change between 1950 and 1975, but significant warming afterwards. Local topographic effects (e.g. wind redistribution of snow and avalanching) are important influences. These small glaciers respond to changes in regional climate; summer temperature alone is a good predictor of the mass balance of Andrews Glacier (r = -0.93). Spring snowfall is also an important factor. That winter precipitation is not statistically significant supports the notion that these small glaciers gain much snow from wind drift and avalanching, making winter snow accumulation almost indifferent to variations in direct snowfall. Less than expected glacier retreat may be due to increased summer cloudiness.

NORTH AMERICAN ELK BUGLE VOCALIZATIONS: MALE AND FEMALE BUGLE CALL STRUCTURE AND CONTEXT

Bugle calls of male North American elk (Cervus elaphus) are common sounds during fall in the Canadian and United States Rocky Mountains. In contrast, bugle calls of female elk are rarely heard. We quantified the acoustic structure of elk bugle calls, which is an essential 1st step to understanding of the function of the call. We also investigated whether motivation‐structural rules apply to these long-distance calls. We measured male elk bugle calls in Rocky Mountain National Park, Colorado, during autumn of 1998 and 1999 and we measured female elk bugle calls on 2 Colorado elk ranches (private establishments that raise elk for commercial purposes) during spring of 2001 and 2002. All bugle calls had 3 segments: on-glide, whistle, and off-glide. Male bugle calls were longer in duration than female bugle calls (P , 0.01). Bugle calls emitted in aggressive interactions had 4 or 5 low-frequency formants, resulting in harsher, wider bandwidth bugles (P , 0.001) compared to the tonal calls emitted in nonaggressive contexts, which lacked formants. Thus, elk bugle calls appear to conform to motivation‐structural rules.

SPATIAL HETEROGENEITY INFLUENCES NATIVE AND NONNATIVE PLANT SPECIES RICHNESS

Spatial heterogeneity may have differential effects on the distribution of native and nonnative plant species richness. We examined the effects of spatial heterogeneity on native and nonnative plant species richness distributions in the central part of Rocky Mountain National Park, Colorado, USA. Spatial heterogeneity around vegetation plots was characterized using landscape metrics, environmental/topographic variables (slope, aspect, elevation, and distance from stream or river), and soil variables (nitrogen, clay, and sand). The landscape metrics represented five components of landscape heterogeneity and were measured at four spatial extents (within varying radii of 120, 240, 480, and 960 m) using the FRAGSTATS landscape pattern analysis program. Akaike's Information Criterion adjusted for small sample size (AICc) was used to select the best models from a set of multiple linear regression models developed for native and nonnative plant species richness at four spatial extents and three levels of ecological hierarchy (i.e., landscape, land cover, and community). Both native and nonnative plant species richness were positively correlated with edge density, Simpson's diversity index and interspersion/juxtaposition index, and were negatively correlated with mean patch size. The amount of variation explained at four spatial extents and three hierarchical levels ranged from 30% to 70%. At the landscape level, the best models explained 43% of the variation in native plant species richness and 70% of the variation in nonnative plant species richness (240-m extent). In general, the amount of variation explained was always higher for nonnative plant species richness, and the inclusion of landscape metrics always significantly improved the models. The best models explained 66% of the variation in nonnative plant species richness for both the conifer land cover type and lodgepole pine community. The relative influence of the components of spatial heterogeneity differed for native and nonnative plant species richness and varied with the spatial extent of analysis and levels of ecological hierarchy. The study offers an approach to quantify spatial heterogeneity to improve models of plant biodiversity. The results demonstrate that ecologists must recognize the importance of spatial heterogeneity in managing native and nonnative plant species.

Historical Fire Cycles in the Canadian Rocky Mountain Parks

Abstract The subject of this article is the fire history of seven contiguous national and provincial parks in the Canadian Rocky Mountains, four to the east of the continental divide and three to the west. Seven centuries of time-since-fire data were combined and arrayed in three sets: all seven parks together, then the east-side and west-side groups separately. Fire cycles were estimated by four different methods: two of them statistical and two deterministic. Statistical evidence of distinct changes in fire regime, always toward a lower burning rate, was uncovered, with transitions in 1760 and 1940 on the east side, and in 1840 on the west side. The principal conclusions were: The seven parks as a unit supported a fire cycle of 60–70 yr for nearly five centuries before 1760. The burning rate then dropped sharply and a longer cycle of about 175 yr prevailed until 1940. Fire history in the combined large parks on the east side was similar to the above. By contrast, the smaller west-side parks group sustained a fire cycle of about 90 yr for at least five centuries before 1840; the burning rate then decreased irregularly to 2000. On the east side, the near absence of burned area after 1940 was attributed to the onset of effective fire protection. Possible prior causes of the earlier transitions on east and west sides include changes in climate or aboriginal fire practices, but this issue is left unresolved.

Assessing exotic plant species invasions and associated soil characteristics: A case study in eastern Rocky Mountain National Park, Colorado, USA, using the pixel nested plot design

Rocky Mountain National Park (RMNP), Colorado, USA, contains a diversity of plant species. However, many exotic plant species have become established, potentially impacting the structure and function of native plant communities. Our goal was to quantify patterns of exotic plant species in relation to native plant species, soil characteristics, and other abiotic factors that may indicate or predict their establishment and success. Our research approach for field data collection was based on a field plot design called the pixel nested plot. The pixel nested plot provides a link to multi-phase and multi-scale spatial modeling-mapping techniques that can be used to estimate total species richness and patterns of plant diversity at finer landscape scales. Within the eastern region of RMNP, in an area of approximately 35,000 ha, we established a total of 60 pixel nested plots in 9 vegetation types. We used canonical correspondence analysis (CCA) and multiple linear regressions to quantify relationships between soil characteristics and native and exotic plant species richness and cover. We also used linear correlation, spatial autocorrelation and cross correlation statistics to test for the spatial patterns of variables of interest. CCA showed that exotic species were significantly ( P < 0.05) associated with photosynthetically active radiation ( r = 0.55), soil nitrogen ( r = 0.58) and bare ground ( r = −0.66). Pearson's correlation statistic showed significant linear relationships between exotic species, organic carbon, soil nitrogen, and bare ground. While spatial autocorrelations indicated that our 60 pixel nested plots were spatially independent, the cross correlation statistics indicated that exotic plant species were spatially associated with bare ground, in general, exotic plant species were most abundant in areas of high native species richness. This indicates that resource managers should focus on the protection of relatively rare native rich sites with little canopy cover, and fertile soils. Using the pixel nested plot approach for data collection can facilitate the ecological monitoring of these vulnerable areas at the landscape scale in a time- and cost-effective manner.

Review of Pickering, America's Switzerland: Estes Park and Rocky Mountain National Park, the Growth Years

Review of Pickering, America's Switzerland: Estes Park and Rocky Mountain National Park, the Growth Years

Recreation as a Spatial Good: Distance Effects on Changes in Recreation Visitation and Benefits

The effects of travel distance on visitation and associated recreation benefits are tested for a large national park. Visitor responses to a survey depicting various natural resource scenarios at Rocky Mountain National Park were used to estimate the effects of distance traveled on nature-based tourism behavior and benefits. Distance was a significant determinant in both the visitation and contingent valuation models. Long-distance visitors were more stable in their visitation patterns in the face of natural resource changes. Marginal recreational benefits per trip increased with distance but at a decreasing rate. However, in-state visitors accrued higher annual benefits because of greater trip frequency. The relative importance of visitor types can help private and public decision-makers better respond to different visitor needs. The findings also provide a unique perspective on consumer spatial tradeoffs and the national value of recreational resources.

Application of a coupled ecosystem-chemical equilibrium model, DayCent-Chem, to stream and soil chemistry in a Rocky Mountain watershed

Atmospheric deposition of sulfur and nitrogen species have the potential to acidify terrestrial and aquatic ecosystems, but nitrate and ammonium are also critical nutrients for plant and microbial productivity. Both the ecological response and the hydrochemical response to atmospheric deposition are of interest to regulatory and land management agencies. We developed a non-spatial biogeochemical model to simulate soil and surface water chemistry by linking the daily version of the CENTURY ecosystem model (DayCent) with a low temperature aqueous geochemical model, PHREEQC. The coupled model, DayCent-Chem, simulates the daily dynamics of plant production, soil organic matter, cation exchange, mineral weathering, elution, stream discharge, and solute concentrations in soil water and stream flow. By aerially weighting the contributions of separate bedrock/talus and tundra simulations, the model was able to replicate the measured seasonal and annual stream chemistry for most solutes for Andrews Creek in Loch Vale watershed, Rocky Mountain National Park. Simulated soil chemistry, net primary production, live biomass, and soil organic matter for forest and tundra matched well with measurements. This model is appropriate for accurately describing ecosystem and surface water chemical response to atmospheric deposition and climate change.

Place as Relationship Partner: An Alternative Metaphor for Understanding the Quality of Visitor Experience in a Backcountry Setting

This article presents empirical evidence to address how some visitors build relationships with a wildland place over time. Insights are drawn from qualitative interviews of recreation visitors to the backcountry at Rocky Mountain National Park in Colorado. The article describes relationship to place as the active construction and accumulation of place meanings. The analysis is organized around three themes that describe how people develop relationships to place: time and experience accrued in place, social and physical interactions in and with the setting, and an active reflective process of regulating sense of identity to affirm commitment to place.

Green-Tailed Towhee Response to Prescribed Fire in Montane Shrubland

Abstract Fire alters the structure and composition of shrublands and affects habitat quality for the associated avifauna. Because shrubland ecosystems have been greatly reduced from their original extent in western North America and fire is increasingly being used to manage these landscapes, a better understanding of how fire affects the associated vegetation and wildlife is imperative. We evaluated the response of Green-tailed Towhees (Pipilo chlorurus) to prescribed fire in the montane shrublands of Rocky Mountain National Park, Colorado during 2002 and 2003. Three to five years following prescribed burning, Green-tailed Towhee density and shrub cover were generally higher in unburned areas. Nests (n = 179) were located in unburned vegetation; within burned sites, all nests were in remnant patches. Green-tailed Towhee nest survival was 57% (95% CI = 49%–65%) across the two years of the study. More than half of the nests were in common juniper (Juniperus communis) shrubs, and nest survival was higher for nests in junipers than those in other shrub species. Daily nest survival rates were lower at the site with the highest density of towhees and declined over the breeding season. With regard to shrub cover, opposite trends were observed for nest-site selection and nest survival: nest plots had greater shrub cover than non-nest plots, but nest survival decreased with increasing shrub cover. Because shrub cover affects towhee density and nest survival in conflicting ways, fire management at Rocky Mountain National Park alters both habitat availability and suitability for Green-tailed Towhees.

Implications of climate and environmental change for nature-based tourism in the Canadian Rocky Mountains: A case study of Waterton Lakes National Park

In western North America, Rocky Mountain national parks represent a major resource for nature-based tourism. This paper examines how climate change may influence park tourism in the Rocky Mountain region by focusing on both the direct and indirect impacts of climate change for visitation to Waterton Lakes National Park (WLNP) (Alberta, Canada). A statistical model of monthly visitation and climate was developed to examine the direct impact of climate change on visitation. The model projected that annual visitation would increase between 6% and 10% in the 2020s and between 10% and 36% in the 2050s. To explore how climate-induced environmental change could also indirectly affect visitation, a visitor survey was used ( N = 425 ). The environmental change scenarios for the 2020s and 2050s were found to have minimal influence on visitation, however the environmental change scenario for the 2080s (under the warmest climate change conditions) was found to have a negative effect on visitation, as 19% of respondents indicated they would not visit the park and 37% stated they would visit the park less often. The contrasting result of the two analyses for the longer-term impact of climate change was a key finding. The management implications of these findings and methodological challenges associate with climate change impact assessment for tourism are also discussed.

America's Switzerland: Estes Park and Rocky Mountain National Park, the growth years

America's Switzerland: Estes Park and Rocky Mountain National Park, the growth years

Beaver dams and overbank floods influence groundwater–surface water interactions of a Rocky Mountain riparian area

Overbank flooding is recognized by hydrologists as a key process that drives hydrogeomorphic and ecological dynamics in mountain valleys. Beaver create dams that some ecologists have assumed may also drive riparian hydrologic processes, but empirical evidence is lacking. We examined the influence of two in‐channel beaver dams and a 10 year flood event on surface inundation, groundwater levels, and flow patterns in a broad alluvial valley during the summers of 2002–2005. We studied a 1.5 km reach of the fourth‐order Colorado River in Rocky Mountain National Park (RMNP), Colorado, USA. The beaver dams and ponds greatly enhanced the depth, extent, and duration of inundation associated with floods; they also elevate the water table during both high and low flows. Unlike previous studies we found the main effects of beaver on hydrologic processes occurred downstream of the dam rather than being confined to the near‐pond area. Beaver dams on the Colorado River caused river water to move around them as surface runoff and groundwater seepage during both high‐ and low‐flow periods. The beaver dams attenuated the expected water table decline in the drier summer months for 9 and 12 ha of the 58 ha study area. Thus we provide empirical evidence that beaver can influence hydrologic processes during the peak flow and low‐flow periods on some streams, suggesting that beaver can create and maintain hydrologic regimes suitable for the formation and persistence of wetlands.

Species–area curves indicate the importance of habitats’ contributions to regional biodiversity

Abstract 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 m 2 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 ( r 2 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.