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Item Biogeochemistry and hydrology of three alpine proglacial environments resulting from glacier retreat(Montana State University - Bozeman, College of Letters & Science, 2008) Bruckner, Monica Zanzola; Chairperson, Graduate Committee: Mark L. SkidmoreProglacial environments, formed by glacier retreat, exhibit distinct characteristics in discharge, water temperature, water residence time, and dissolved ion, carbon, and suspended sediment concentrations. The unnamed alpine glacier at the headwaters of the Wheaton River, Yukon, Canada, provides an ideal setting to compare deglaciation processes that result in three different proglacial environments. The glacier has evolved from occupying one large catchment (~4 km²) to two smaller catchments (each ~2 km²) via glacier thinning and net mass loss, forming two lobes separated by a medial moraine. Field observations revealed neither crevasses nor evidence of subglacial drainage outlets and suggested this glacier had a non-temperate thermal regime with meltwater predominantly flowing from supraglacial and ice marginal sources. Climate and bedrock geology were similar for the subcatchments, providing a natural laboratory to compare deglaciation processes. This study compared the hydrology and biogeochemistry of three outlet streams from this glacier: one stream drained a proglacial lake which is fed by meltwater from the lower west lobe, a second stream drained the upper west lobe, and a third stream was the major drainage outlet for the east lobe. Hydrologic monitoring over the 2006 melt season (June-August) and analyses of water samples for dissolved ion content and carbon indicated that the meltwaters are dominated by Ca²+ and HCO 3-, which are derived from biogeochemical weathering of crustal materials. The study demonstrated that the presence of the proglacial lake, which acted as a meltwater reservoir, measurably modified meltwater residence time, water temperature, water chemistry, and bacterial biomass relative to the proglacial streams. Rock:water interaction between meltwater and medial morainal sediment and fine-grained, reactive glacial flour suspended in the streams and the lake water column also enhanced biogeochemical weathering within the catchment. Thus, this study provided a small-scale example for how differences in proglacial environments and water flow paths affect headwater hydrology and biogeochemistry. This study was the first of its kind in the Coast Mountains, Yukon, Canada, and results presented here aid in the understanding of how proglacial environments created by climate-induced glacier retreat affect hydrochemistry, hydrology, and carbon dynamics in remote high elevation environments.Item Alpine and cliff ecosystems in the North-Central Rocky Mountains(Montana State University - Bozeman, College of Letters & Science, 2006) Aho, Ken Andrew; Chairperson, Graduate Committee: Theodore W. Weaver; D. Roberts (co-chair)Data collection and analysis for managed wild lands is vital to their effective stewardship. To address this I gathered and analyzed data for largely undocumented alpine and cliff ecosystems located in the North-Central Rocky Mountains. This information should aid in decision-making processes for regional land managers and increase the overall ecological understanding of these systems. This manuscript includes detailed community analyses of alpine vegetation and its environment on andesitic-volcanic substrates in the Washburn Range and the Northern Absarokas. It also places the Washburn Range and Northern Absarokas into a regional non-volcanic context by comparing them to alpine areas in the Beartooth Mountains. Cliff communities were studied to record common species and to describe variation with respect to water and substrate gradients. An understanding of both alpine and cliff systems is important given the growing presence of exotic mountain goats (Oreomnos americanus) in the region, and concerns over the impact of global climate change to the Greater Yellowstone Ecosystem, particularly in alpine areas. I also present here a number of original methods which should be of interest to ecologists. These include (1) methods for identifying objectively appropriate vegetation classification methods, and finding the correct number of data clusters in datasets, (2) methods for studying important environmental parameters on rock surfaces, and (3) a new protocol for efficiently determining soil water potentials.