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Item Hydrothermal influences on the Holocene environmental history of central Yellowstone National Park(Montana State University - Bozeman, College of Letters & Science, 2020) Schiller, Christopher Michael; Chairperson, Graduate Committee: Cathy Whitlock; Cathy Whitlock, Kathryn L. Elder, Nels A. Iverson and Mark B. Abbott were co-authors of the article, 'Erroneously old radiocarbon ages from terrestrial pollen concentrates in Yellowstone Lake, Wyoming, USA' in the journal 'Radiocarbon' which is contained within this dissertation.; Rosine Cartier, Cathy Whitlock and Lisa A. Morgan were co-authors of the article, 'Multi-proxy record of Holocene paleoenvironmental conditions from Yellowstone Lake, Wyoming, USA' submitted to the journal 'Quaternary science reviews' which is contained within this dissertation.; Cathy Whitlock, Sabrina R. Brown and Petra Zahajska were co-authors of the article, 'Holocene geo-ecological evolution in Lower Geyser Basin, Yellowstone National Park' submitted to the journal 'Geological Society of America bulletin' which is contained within this dissertation.; Cathy Whitlock, Mio Alt and Lisa A. Morgan were co-authors of the article, 'Vegetation responses to Quaternary volcanic and hydrothermal disturbances in the northern Rocky Mountains and Greater Yellowstone Ecosystem' in the journal 'Palaeogeography, Palaeoclimatology, Plaeoecology' which is contained within this dissertation.The postglacial vegetation history of Yellowstone National Park is well established by past paleoecological studies, but the role of hydrothermal activity--pervasive in areas of the park--in that history is poorly understood. To address this unknown, pollen and charcoal records were examined from lake sediment cores at multiple sites in central Yellowstone National Park to reconstruct Holocene vegetation. First, radiocarbon ages obtained from pollen concentrates were compared with other age controls at Yellowstone Lake, revealing ages that were up to 4300 cal years too old. Erroneous ages were due to either old carbon contamination from magmatic or hydrothermally degassed CO 2 or old pollen reworked from an unknown source. Second, Holocene vegetation and fire history were reconstructed from a Yellowstone Lake sediment core. The record was characterized by gradually increasing closure or extent of Pinus contorta forest and increasing fire activity to the present, consistent with reduced summer insolation creating cooler, effectively wetter conditions in central Yellowstone National Park. No impact of hydrothermal activity was detected in the regional Holocene-long vegetation and fire histories. Third, Holocene vegetation and fire history were studied at Goose Lake in Lower Geyser Basin, an area with abundant modern hydrothermal activity. The vegetation and fire history diverged from the regional trend at 3800 cal yr BP, synchronous with geochemical indicators indicating reorganization of hydrothermal activity in the basin, suggesting an abrupt ecological response to shifting hydrothermal activity. Finally, a variety of volcanic and hydrothermal processes were investigated as disturbances in the Northern Rocky Mountains and Yellowstone National Park through high-resolution pollen analysis. Hydrothermal explosion deposits were found to be synchronous with conifer morality, in some records, indicating that the effects of hydrothermal explosions are local and short-lived. At a regional scale, it is evident that vegetation changes were chiefly responding to millennial-scale, insolation-driven climate change. However, the impacts of hydrothermal activity were locally important where pervasive, as in Lower Geyser Basin, and in areas recently affected by hydrothermal explosions.Item Disentangling anthropogenic and natural drivers of change in vegetation and fire history along the forest-grassland ecotones of the central United States and Patagonia(Montana State University - Bozeman, College of Letters & Science, 2020) Nanavati, William Parashar; Chairperson, Graduate Committee: Cathy Whitlock; Eric C. Grimm was a co-author of the article, 'Humans, fire, and ecology in the southern Missouri Ozarks' in the journal 'The holocene' which is contained within this dissertation.; Cathy Whitlock, Valeria Outes and Gustavo Villarosa were co-authors of the article, 'A holocene history of Araucaria araucana in northernmost Patagonia' submitted to the journal 'Journal of biogeography' which is contained within this dissertation.; Cathy Whitlock, Virginia Iglesias and Maria Eugenia de Porras were co-authors of the article, 'Postglacial vegetation, fire, and climate history along the eastern Andes, Argentina and Chile (lat. 41-55°S)' in the journal 'Quaternary science reviews' which is contained within this dissertation.Disentangling anthropogenic and natural drivers of vegetation and fire history at different spatiotemporal scales is a fundamental challenge in Earth Systems science. To better understand the role of past human ignition in altering long-term ecosystem dynamics, we rely on the anthropogenic fire regime conceptual model proposed by Guyette et al. (2002) in the central U.S. Ozarks. The synthesis of new and existing pollen and charcoal records, and their integration with archaeological, ethnographic, and independent paleoclimate records is used to test the anthropogenic fire regime conceptual model at a longer time scale in the central U.S. Ozarks. Following its validation, this conceptual model is applied to the forest-steppe ecotone east of the Patagonian Andes (38-55°S) for the first time. Although it is well established that Patagonian vegetation and fire history for most of the postglacial period was governed by the strength and position of the Southern Westerly Wind (SWW) storm tracks, the influence of land use since the arrival of American Indians to the region ~12,000 years ago remains unclear. From the late glacial to early Holocene, region-wide increases in fire were associated with aridity while the SWW were weakened and south of their present position. Between ~7000-4000 cal yr BP, increased arboreal taxa and decreased fire throughout Patagonia suggest wet conditions as the SWW moved northward to their present position. After ~4000 cal yr BP, a combination of increased land use and greater climate variability, led to spatially heterogeneous but generally rising fire activity along the forest-steppe ecotone. When trends in the vegetation and fire history of individual sites are compared to each other and to the archaeological record, however, it becomes apparent that American Indians may have served as an important source of ignition, locally increasing landscape heterogeneity since their arrival. During the last 100 years, increased Euro-American settlement and land clearance in Patagonia led to native forest loss, more disturbance, and the spread of introduced taxa along the eastern flanks of the Andes. These ecological changes in the recent century far outweigh thousands of years of American Indian influence on fire and vegetation history.Item Understanding the present and past climate-fire-vegetation dynamics of southern South America (40 - 45°S)(Montana State University - Bozeman, College of Letters & Science, 2020) Ogunkoya, Ayodele Gilbert; Chairperson, Graduate Committee: Benjamin Poulter; David Roberts (co-chair); Jed O. Kaplan, Cathy Whitlock, William Nanavati, Benjamin Poulter and David Roberts were co-authors of the article, 'Drivers of modeled forest cover change in southern South America are linked to climate and CO^2' which is contained within this thesis.; Jed O. Kaplan, Cathy Whitlock, William Nanavati, Benjamin Poulter, David Roberts and Steve Hostetler were co-authors of the article, 'Climate drivers of late-glacial to postgalacial forest cover along the eastern Andes of Northern Patagonia (lat. 40 - 45°S)' which is contained within this thesis.The forest-steppe boundary that runs north-to-south along the eastern Andes is particularly dynamic over millennial time scales. Yet the relative role of long-term climate change and fire is poorly understood. In this study, I analyze the potential in using a process-based model in predicting species distribution, and the role fire and climate played in shaping the vegetation and treeline dynamics of Northern Patagonia (lat. 40 - 45 ° S). Paleoecological data, e.g., pollen, has been extensively used to study the relationship between climate and vegetation but has a low spatial resolution to distinguished between climate-fire-vegetation dynamics. Process-based model thus offers a transparent and robust method of incorporating a varying degree of complexity to understand fire behavior and fire-vegetation dynamics. Recently, LPJ-GUESS was parameterized to simulate major regional plant functional type (PFTs) and tree species distributions in this region. The model is able to predict regional species distribution across spatial scales by coupling establishment, growth, and mortality processes. Predicting spatial and temporal scale species distribution cannot be achieved without having the right climate and soil data, the climate data used was downscaled from 50 km to 1 km resolution using Worldclim climate data ( ~ 1 km) as the reference data. LPJ-GUESS model produced regional species distribution with fair to very good agreement with observation. The optimization of bioclimatic parameters and drought tolerance that is related to root depth, adaptability of plant to seasonal drought, and movement of nutrients consistently improved the accuracy of regional prediction of the species range. The model predicted that the vegetation distribution of present-day is mainly determined by climate and CO 2 rather than fire., while forest productivity responds strongly to elevated CO 2. However, based on the employed statistical methods of Canonical Correspondence Analysis (CCA) and Random Forest machine learning, combined with simulation results using paleoclimate. Results show that an increase in winter temperature drives the postglacial species distribution while changes in precipitation control radial growth and seedling establishment in the upper and lower treeline. These findings emphasize the importance of combining paleoecological methods with modeling to disentangle coarse-scale climate drivers from local influences.Item Late Holocene climate, fire, and vegetation history on the northern range, Yellowstone National Park(Montana State University - Bozeman, College of Letters & Science, 2019) Firmage, David Samuel; Chairperson, Graduate Committee: Cathy WhitlockYellowstone National Park is an iconic natural landscape that encompasses unique geologic features as well as a diverse and ecologically important flora and fauna. The ecological resilience of the Northern Range of the park, home to the park's ungulate herds, faces an uncertain future with a projected warming climate over the next century. Understanding the variability of vegetation organization in response to past changes in climate can help park managers plan for future climate scenarios. Lake sediment cores from two lakes were collected, analyzed for pollen type, charcoal accumulation and lithological components, and compared with other studies to highlight commonalities in fire-histories and vegetation trends across the Northern Range over the past 4000 cal yr BP. Foster Lake the records suggest fire-episodes and changes to lake productivity and between ~3500-2900 cal yr BP, large intense fire-episodes between ~2500-2150 cal yr BP, ~1000 cal yr BP and frequent large fire episodes from ~700 cal yr BP to the present day. Floating Island Lake records between ~4000-3000 cal yr BP suggest the site experienced infrequent, large fire episodes concurrent with periods of protracted drought and decreases in water level. Between ~3000-1500 low intensity fire episodes were common, punctuated by infrequent large fire episodes at ~2900, ~2250, ~2050 and ~1880 cal yr BP. During the last ~1ka two fire episodes were recorded at Floating Island Lake, at ~1030 cal yr BP coincident with the Medieval Climate Anomaly, and 270~ cal yr BP during the Little Ice Age. A comparison of fire histories from studies spanning the Northern Range shows that during periods of protracted drought large fire episodes are common across the landscape, and that during periods of moderate climate fire size and severity is likely modulated by local site controls such as topography and vegetation structure. This study shows that fire episodes in the Northern Range have occurred as a spatial and temporal mosaic, and are likely to continue to do so. Additionally, this study increases our understanding of how vegetation structure and fire regimes in the Northern Range have varied as a result of a range of climate conditions in the past. Such baseline information helps us anticipate some of the ecological responses that may occur in the decades ahead with global warming.Item Building and fire code enforcement in Billings : recommendations for reform(Montana State University - Bozeman, 1984) Riney, Lynette ClaudiaItem Short-term changes in vegetation and soil in response to a bulldozed fireline in northern great plains grasslands(Montana State University - Bozeman, College of Agriculture, 2015) Tulganyam, Samdanjigmed; Chairperson, Graduate Committee: Craig Carr; Craig A. Carr was a co-author of the article, 'Short-term vegetation response to bulldozed fireline in northern great plains grasslands' submitted to the journal 'Northwest science' which is contained within this thesis.; Craig A. Carr was a co-author of the article, 'Short-term soil response to bulldozed fireline in northern great plains grasslands' submitted to the journal 'Northwest science' which is contained within this thesis.The objectives of this study was to quantify the ecological cost of bulldozed fireline in comparison to burned and unburned sites and draw a management implications for ranchers and land owners. Vegetation cover and abundance were determined with biomass clipping and line point intercept method as separate functional groups across the bladed, burned, and unburned sites in two locations, north central and south west Montana for two years. Study area encompassed idaho fescue and bluebunch wheatgrass dominated north facing slope in Redbluff and rough fescue and bluebunch dominated grassland in Havre. After quantifying vegetation responses, top soil horizon depth, bulk density, aggregate stability and runoff and sediment yield were determined to quantify soil response to bulldozed fireline. In general, burned site did not differ from unburned site particularly by the second year after the fire. In other words fire was not detrimental to the rangeland condition. Whereas bulldozed fireline altered primary ecological processes, particularly nutrient cycle and hydrologic functioning, by mechanically removing native plant species, creating exposed bare ground which was susceptible to soil erosion and invasion of competitive non-natives.Item Understanding the role of biophysical setting in aspen persistence(Montana State University - Bozeman, College of Letters & Science, 2003) Brown, Kathryn; Chairperson, Graduate Committee: Andrew HansenItem Elk effects on sagebrush-grassland after fire on Yellowstone's Northern Range(Montana State University - Bozeman, College of Agriculture, 2001) Rens, Reyer JanItem Quantifying tansy ragwort (Senecio jacobaea) population dynamics and recruitment in northwestern Montana(Montana State University - Bozeman, College of Agriculture, 2003) Trainor, Meghan AnnItem Grasslands of the Missouri Coteau and their relationship to environment(Montana State University - Bozeman, College of Letters & Science, 2003) Plaggemeyer, John Bernard; Chairperson, Graduate Committee: Theodore W. Weaver