The Murray Site: a Late Prehistoric Game Drive System in the Colorado Rocky Mountains

Abstract

The Murray site (5 BL 65) “is a tundra game drive near the summit of Mount Albion, Boulder County, Colorado. Rock walls and lines of cairns at the site were used in driving large grazing animals from a broad saddle onto a narrow ridgecrest, where they were killed from ambush by hunters concealed in shallow, rock-rimmed pits. Geological, lichenometric, and radiocarbon dating show that the walls and pits were constructed between about 950 and 1000 yr. BP. Initial use of the system was by people related to the Hog Back Phase (Nelson 1971), who wintered in the Front Range foothills, and who hunted north and south along the continental divide in summer and fall. The site was later modified and re-used by an unidentified Late Prehistoric complex.     

Classification and ordination in the Indian Peaks area,Colorado Rocky Mountains

Summary A mid-latitude, Northern Hemisphere alpine vegetation in the Colorado Rocky Mountains was suitable for analysis by syntaxonemie and numerical methods, which interpreted the Braun-Bianquet association data, distributed by habitat and vegetation dominance types, correspondingly. Classification and ordination yielded complementary, interpretable results, which combined were more informative than results of either technique alone. Syntaxonomic results can faeilitate the interpretation of numerical results; the syntaxonomic relationships can be clarified by the results of numerical analysis.Alliances and orders of the Braun-Blanquet hierarchy, and their diagnostic taxa groups were derived by numerical methods from an association/taxa matrix. On the basis of this matrix, numerical methods demonstrated some of the environmental gradient complexes controlling the compositional variation. The compositional distinctiveness and uniformity of orders and alliances parallel environmental distictiveness and uniformity.The following attributes of the sampled vegetation and environment were probably responsible for the successful combination of syntaxonomic and numerical results: 1. The sampled area as a geographically limited universe, characterized by relative environmental, biotic, and historical distinctiveness and uniformity, 2. The wide range, high diversity, and clear denfinition of habitat and vegetation dominance types. Because it effectively summarizes and simplifies field data, syntaxonomy can play an important role in building local vegetatio models.Most of the figures in this paper are from a book version of a University of Colorado, Department of Environmental, Population, and Organismic Biology, Ph. D. thesis which was produced at the Institute of Arctic and Alpine Research. I would like to thank Dr. P.J. Webber, the thesis advisor, for his support, for suggesting the numerical methods, and for computer programs which were written by W.F. Reid. Vicki Dow, Marilyn Joel, and Karen Sproul drafted the majority of figures. I am grateful to Gwen Archer for editorial help.     

Genetic structure in a montane mayfly Baetis bicaudatus (Ephemeroptera: Baetidae), from the Rocky Mountains, Colorado

1. Populations of a number of sub‐tropical stream insect species have been found to show unexpected patterns of genetic variation, with more differences between samples from the same stream than between whole streams or between subcatchments. Many samples also showed deviations from Hardy–Weinberg proportions. It has been proposed that these patterns result from limited numbers of matings contributing to a given stream reach, because adults emerge throughout the year, and low levels of larval drift between reaches. These patterns may be less likely in a northern hemisphere montane species with synchronous emergence of adults and high levels of drift. We tested the hypothesis that patterns of genetic variation in a montane mayfly from the Rocky Mountains, Colorado, would reflect a pattern of ‘isolation by distance’ with samples from the same creek being more similar than samples from different creeks and that deviations from Hardy–Weinberg proportions would be minimal. 2. Based on allozyme variation, the hypothesis of minimal deviations from Hardy–Weinberg proportions was not supported and there was no evidence of isolation by distance. Nevertheless the levels of differentiation among samples from within the same stream were less than those reported for most subtropical species. 3. Results from analysis of a fragment of the cytochrome oxidase gene (subunit 1) revealed contrasting patterns. The levels of genetic differentiation were an order of magnitude higher between streams than among samples within streams. In addition, although there was no significant isolation by distance effect overall, a nested clade analysis provided evidence for restricted gene flow with isolation by distance for some clades. 4. We suggest that these contrasting results may reflect the differences in male and female dispersal patterns. While differentiation at nuclear gene markers (allozymes) give information about both male and female dispersal, mitochondrial DNA markers reflect only female dispersal. We suggest that in this species, female dispersal may be more restricted, perhaps mostly along stream channels, whereas male dispersal is more widespread. An alternative explanation for the different results is the different evolutionary rates of the mitochondrial and nuclear markers.     

Environmental drivers of subalpine and alpine fen vegetation in the Southern Rocky Mountains,Colorado, USA

Fens are widely distributed wetlands worldwide and provide vital habitat for plant and animal species in mountainous regions. Alpine fens are rare in the Rocky Mountains and concentrated in the San Juan Mountains where broad regions at high elevation have relatively level topography and suitable climate to favor peat accumulation. Studies of montane and boreal peatlands have identified water chemistry as a main driver of vegetation composition. This study investigated whether similar drivers of vegetation composition are important for alpine and subalpine fens in the San Juan Mountains of Colorado, USA. Water chemistry variables were most important in structuring subalpine and alpine fen vegetation. However, these variables explained considerably less variation in alpine than subalpine fen vegetation. In addition, lower variance of water chemistry in alpine fens did not lead to lower beta diversity of vegetation in alpine than in subalpine fens. Although alpine and subalpine fen vegetation supports similar beta diversity, key differences occur in the environmental drivers of their vegetation composition.     

Microbial population dynamics in an extreme environment: controlling factors in talus soils at 3750 m in the Colorado Rocky Mountains

Variation of CH₄ emissions over a three-year period was studied in a reed-dominated (Phragmites australis) littoral transect of a boreal lake undergoing shoreline displacement due to postglacial rebound. The seasonal variation in plant-mediated CH₄ emissions during open-water periods was significantly correlated with sediment temperature. The highest plant-mediated emission rates (up to 2050 mg CH₄ m^–2 d^–1) were found in the outermost reed zone, where culms of the previous growing seasons had accumulated and free-floating plants grew on the decomposing culms. In reed zones closer to the shoreline as well as in mixed stands of reed and cattail, the maximum daily rates were usually > 500 mg CH₄ m^–2 d^–1. The total plant-mediated CH₄ emission during the open-water period was significantly correlated with the seasonal maximum of green shoot biomass. This relationship was strongest in the continuously flooded (water depth > 25 cm) outermost zones. In this area, emissions through ebullition were of greatest importance and could exceed plant-mediated emissions. In general, total emissions of the open-water periods varied from ca. 20 to 50 g CH₄ m^–2 a^–1, but in the outermost reed zone, the plant-mediated emissions could be as high as 123 g CH₄ m^–2 a^–1; ebullition emissions from this zone reached > 100 g CH₄ m^–2 a^–1. The proportion of CH₄ released in winter was usually < 10% of annual emissions. Emissions of CH₄ were higher in this flooded transgression shore the than those measured in boreal peatlands, but the role of ancient carbon stores as a substrate supply compared with recent anthropogenic eutrophication is unknown.     

Restoring the Vegetation of Mined Peatlands in the Southern Rocky Mountains of Colorado, U.S.A.

South Park is a high‐elevation, semi‐arid, treeless intermountain basin in central Colorado. A few extreme rich fens occur on the western margin and in the center of South Park where regional and local groundwater flow systems discharge to the ground surface. Over the past 40 years there has been extensive peat mining in these fens, but restoration methods have yet to be developed and successfully applied. The first part of this study compared the naturally reestablished vegetation on six mined peatlands with six pristine sites, while the second part of the study tested different revegetation techniques in 27 plots with varying depths to the water table. The six mined sites had only 30 plant species as compared with 122 species in the unmined sites; 43% of the species in the mined sites were not present in the undisturbed fens. Even after 40 years the sedges and willows that dominate the undisturbed sites were largely absent on the mined sites. The revegetation experiments seeded eight species, transplanted Carex aquatilis (water sedge) seedlings, transplanted rhizomes from six species, and transplanted four species of willow cuttings. Of the eight species seeded, only Triglochin maritima (arrowgrass) germinated and established seedlings. C. aquatilis seedlings, rhizome transplants of C. aquatilis, Kobresia simpliciuscula (elk sedge), and Juncus arcticus (arctic rush), and willow cuttings all had differing patterns of survival with respect to the annual maximum height of the water table. These results indicate that the dominant species can be successfully reintroduced to mined surfaces with the appropriate hydrologic conditions, but human intervention will be necessary to rapidly re‐establish these species. The slow rate of peat accumulation means that restoration of the mined fens will require hundreds, if not thousands, of years.     

The Organization of Male and Female Labor in Foraging Societies: Implications for Early Paleoindian Archaeology

I use cross-cultural ethnographic data to explore the relationship between male and female subsistence labor among hunter-gatherer populations by examining data regarding resource procurement, time allocation, and task differentiation between the sexes relative to dependence on hunted foods. The findings indicate that female foragers generally perform a variety of nonsubsistence collection activities and preferentially procure high-return resources in hunting-based economies. I develop ideas about predictable relationships concerning the amount of time female foragers expend on subsistence and technological tasks relative to the dietary contribution of meat. I then use ethnographic trends to evaluate archaeological assumptions regarding the sexual division of labor in prehistoric foraging contexts, focusing on the dichotomous views of Clovis labor organization. I argue that archaeological interpretations of prehistoric labor roles in hunting-based foraging societies are commonly polarized between stereotypical views of male and female subsistence behaviors. I develop an interpretation of Early Paleoindian labor organization, emphasizing female labor in the production of material goods and the procurement of low-risk plant and animal resources based on global economic trends among foragers.     

Persistence of high elevation fens in the Southern Rocky Mountains,on Grand Mesa,Colorado, U.S.A.

Small headwater fens at high elevations exist in the dry climatic regime of western Colorado, despite increasing demands for water development since the 1800’s. Fens on Grand Mesa have accumulated plant material as peat for thousands of years due to cold temperatures and consistently saturated soils. The peatlands maintain unique plant communities, wildlife habitat, biodiversity, and carbon storage. We located and differentiated 88 fens from 15 wet meadows and 2 marshes on Grand Mesa. Field work included determining vegetation, soils, moisture regimes, and impacts from human activities. All fens were groundwater-supported systems that occurred in depressions and slopes within sedimentary landslide and volcanic glacial till landscapes. Fens occupied 400 ha or less than 1 % of the 46,845 ha research area and ranged in size from 1 to 46 ha. Peat water pH in undisturbed sites ranged from 4.3 to 7.1. Most fens had plant communities dominated by sedges (Carex) with an understory of brown mosses. Variation in vegetation was controlled by stand wetness, water table level, organic C, conductivity (EC), and temperature °C. Fen soils ranged from 13.6 to 44.1 % organic C with a mean of 30.3 %. Species diversity in fens was restricted by cold short growing seasons, stressful anaerobic conditions, and disturbance. Multivariate analysis was used to analyze relationships between vegetation, environmental, and impact variables. Stand wetness, water table level, OC, electrical conductivity (EC), and temperature were used to analyze vegetation variance in undisturbed fens, wet meadows, and marshes. Vegetation composition in impacted fens was influenced by flooding, sedimentation, stand wetness, water table level, OC, EC, and temperature. Hydrologically modified fens supported 58 plant species compared to 101 species in undisturbed fens. Analysis of historical 1936–2007 aerial photographs and condition scalars helped quantify impacts of human activities in fens as well as vegetation changes. Fourteen fens had evidence of peat subsidence, from organic soil collapse, blocks of peat in the margins, soil instability, and differences in surface peat height between the fen soil surface and the annually flooded soil surface. Of 374 ha of fens in the Grand Mesa study area, 294 ha (79 %) have been impacted by human activities such as ditching, drainage, flooding, or vehicular rutting. Many fens had little restoration potential due to severe hydrological and peat mass impacts, water rights, or the cost of restoration.     

From Casta to Californio: Social Identity and the Archaeology of Culture Contact

In culture contact archaeology, studies of social identities generally focus on the colonized–colonizer dichotomy as the fundamental axis of identification. This emphasis can, however, mask social diversity within colonial or indigenous populations, and it also fails to account for the ways that the division between colonizer and colonized is constructed through the practices of colonization. Through the archaeology of material culture, foodways, and architecture, I examine changing ethnic, racial, and gendered identities among colonists at El Presidio de San Francisco, a Spanish-colonial military settlement. Archaeological data suggest that military settlers were engaged in a double material strategy to consolidate a shared colonial identity, one that minimized differences among colonists and simultaneously heightened distinctions between colonists and local indigenous peoples.     

Polyploid and hybrid evolution in roses east of the Rocky Mountains

This study investigates the impact of hybridization and polyploidy in the evolution of eastern North American roses. We explore these processes in the Rosa carolina complex (section Cinnamomeae), which consists of five diploid and three tetraploid species. To clarify the status and origins of polyploids, a haplotype network (statistical parsimony) of the glyceraldehyde 3-phosphate dehydrogenase (GAPDH) nuclear gene was estimated for polyploids of the complex and for diploids of section Cinnamomeae in North America. A genealogical approach helped to decipher the evolutionary history of polyploids from noise created by hybridization, incomplete lineage sorting, and allelic segregation. At the diploid level, species west of the Rocky Mountains are distinct from eastern species. In the east, two groups of diploids were found: one consists of R. blanda and R. woodsii and the other of R. foliolosa, R. nitida, and R. palustris. Only eastern diploids are involved in the origins of the polyploids. Rosa arkansana is derived from the blanda-woodsii group, R. virginiana originated from the foliolosa-nitida-palustris group, and R. carolina is derived from a hybrid between the two diploid groups. The distinct origins of these polyploid taxa support the hypothesis that the three polyploids are separate species.     

Biogeochemical Change During Climate-Driven Afforestation: A Paleoecological Perspective from the Rocky Mountains

Shifts in an ecosystem’s state can alter biogeochemical cycling and the extent of nutrient conservation within a terrestrial landscape on multiple time scales. Transient biogeochemical changes may follow disturbance and succession, although persistent long-term differences may exist under different climates and vegetation types. We evaluate the potential for such biogeochemical changes in the context of long-term ecological history by measuring the nitrogen isotope composition of organic matter in a lake sediment core. We targeted Little Windy Hill Pond (LWH) in the Medicine Bow Mountains, Wyoming because reconstructions of the lake level, fire, and vegetation histories from the lacustrine sediments indicated a century-scale transformation from an arid, shrub-dominated landscape to a sub-alpine, tree-dominated ecosystem with extensive woody cover and large, live biomass pools. We demonstrate that the afforestation at the beginning of the Holocene transformed the Artemisia-dominated ecosystem, which had persisted for millennia during the Pleistocene. The changes affected nitrogen cycling dynamics, especially through intensified nutrient conservation when live biomass pools increased with greater woody cover. The LWH sediments record a baseline δ¹⁵N shift from 2.2–3.0 to 0.3–2.0‰ as less ¹⁵N-enriched organic matter accumulated in the lake. We also observed a transient pattern of maximum nutrient conservation and minimum δ¹⁵N values as terrestrial biomass increased during the aggradation (~175 years) and transition phases of ecological succession. Our nitrogen isotope results support theoretical expectations of long-term biogeochemical dynamics as nutrient conservation increases during afforestation.     

Assessing the sensitivity of alpine lakes and ponds to nitrogen deposition in the Canadian Rocky Mountains

To demonstrate the sensitivity of aquatic ecosystems to forecasted increases in nitrogen deposition along the eastern ranges of the Canadian Rocky Mountains, we conducted midsummer limnological surveys of 29 remote alpine lakes and ponds via helicopter in 2007. Chemical analysis of water and in vitro nitrogen-enrichment bioassays of phytoplankton collected from each site were performed to estimate nutrient limitation. Use of a common chemical index for nutrient limitation (total dissolved inorganic nitrogen: total phosphorus; DIN:TP) together with supportive experimental evidence revealed nitrogen limitation in only 14% of the cases. Shallow (≤1 m maximum depth) ponds were more likely to be nitrogen-limited than lakes, especially as the former exhibited a significantly lower mean DIN:TP ratio of 7.4 during the late summer. Chemical and bioassay-based inferences of nitrogen limitation agreed in 74.5% of the cases, owing mainly to evidence of phosphorus limitation of the surveyed lake ecosystems (mean DIN:TP = 18) being supported by nonsignificant responses of their phytoplankton to nitrogen amendment. Our findings reveal that increased nitrogen deposition should not result in immediate widespread eutrophication of the Canadian Rockies; however, certain alpine ponds appeared nitrogen-limited, making them sensitive early indicators of the potential effects of anthropogenic nitrogen deposition in remote mountainous regions.     

Why replication is important in landscape genetics: American black bear in the Rocky Mountains

We investigated how landscape features influence gene flow of black bears by testing the relative support for 36 alternative landscape resistance hypotheses, including isolation by distance (IBD) in each of 12 study areas in the north central U.S. Rocky Mountains. The study areas all contained the same basic elements, but differed in extent of forest fragmentation, altitude, variation in elevation and road coverage. In all but one of the study areas, isolation by landscape resistance was more supported than IBD suggesting gene flow is likely influenced by elevation, forest cover, and roads. However, the landscape features influencing gene flow varied among study areas. Using subsets of loci usually gave models with the very similar landscape features influencing gene flow as with all loci, suggesting the landscape features influencing gene flow were correctly identified. To test if the cause of the variability of supported landscape features in study areas resulted from landscape differences among study areas, we conducted a limiting factor analysis. We found that features were supported in landscape models only when the features were highly variable. This is perhaps not surprising but suggests an important cautionary note - that if landscape features are not found to influence gene flow, researchers should not automatically conclude that the features are unimportant to the species' movement and gene flow. Failure to investigate multiple study areas that have a range of variability in landscape features could cause misleading inferences about which landscape features generally limit gene flow. This could lead to potentially erroneous identification of corridors and barriers if models are transferred between areas with different landscape characteristics.     

Prevalence of antibodies to canine parvovirus and distemper virus in wolves in the Canadian Rocky Mountains

Wild carnivores are often exposed to diseases via contact with peridomestic host species that travel through the wildland-urban interfaces. To determine the antibody prevalences and relationships to human activity for two common canid pathogens, we sampled 99 wolves (Canis lupus) from 2000 to 2008 for antibodies to canine parvovirus (CPV) and canine distemper virus (CDV) in Banff and Jasper National Parks and surrounding areas of the Canadian Rockies. This population was the source for wolves reintroduced into the Northern Rockies of the US. Of 99 wolves sampled, 94 had detectable antibody to CPV (95%), 24 were antibody-positive for CDV (24%), and 24 had antibodies to both pathogens (24%). We tested whether antibody prevalences for CPV and CDV were higher closer to human activity (roads, town sites, First Nation reserves) and as a function of sex and age class. Wolves ≥2 yr old were more likely to be have antibodies to CPV. For CDV, male wolves, wolves ≥2 yr, and those closer to First Nation reserves were more likely to have antibodies. Overall, however, we found minimal support for human influence on antibody prevalence for CDV and CPV. The similarity between our antibody prevalence results and results from recent studies in Yellowstone National Park suggests that at least in the case of CDV, and perhaps CPV, these could be important pathogens with potential effects on wolf populations.