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Full-Text Articles in Life Sciences

Multi-Proxy Reconstructions Of Holocene Environmental Change And Catchment Biogeochemistry Using Algal Pigments And Stable Isotopes Preserved In Lake Sediment From Baffin Island And Iceland, Christopher Roth Florian Jan 2016

Multi-Proxy Reconstructions Of Holocene Environmental Change And Catchment Biogeochemistry Using Algal Pigments And Stable Isotopes Preserved In Lake Sediment From Baffin Island And Iceland, Christopher Roth Florian

Geological Sciences Graduate Theses & Dissertations

Lake sediments provide a continuous record of environmental change, integrating information about multiple biogeochemical processes occurring within the lake and catchment. Much of this is recorded by the chemical characteristics of sedimentary organic matter, which can be used as a proxy for past conditions. This dissertation examines Holocene lake sediment records from Baffin Island and Iceland, which, as a result of Arctic amplification feedbacks, are particularly sensitive to changes in climate. We integrated sedimentary algal pigments with more commonly used proxies such as stable isotopes, C:N ratio, and biogenic silica in order to derive a more complete understanding of ...


Conifer Regeneration After Wildfire In Low-Elevation Forests Of The Colorado Front Range: Implications Of A Warmer, Drier Climate, Monica T. Rother Jan 2015

Conifer Regeneration After Wildfire In Low-Elevation Forests Of The Colorado Front Range: Implications Of A Warmer, Drier Climate, Monica T. Rother

Geography Graduate Theses & Dissertations

In recent years, concern has grown among researchers, land managers, and the public regarding potential shifts in forest resiliency to disturbances such as wildfire under warming climate conditions. We examined conifer regeneration after fire in low-elevation, ponderosa pine (Pinus ponderosa) forests of the Colorado Front Range (CFR). Given preliminary observations of limited post-fire conifer establishment, we developed the general hypothesis that warming temperatures and associated drought are less suitable for post-fire conifer regeneration. We surveyed juvenile conifer densities in six recently burned areas of the CFR and found that juvenile ponderosa pine and Douglas-fir (Pseudotsuga menziesii) densities were typically lower ...


Characterizing Metrics And Outcomes Of Stress In A Climate-Sensitive Species, The American Pika, Jennifer Lee Wilkening Jan 2014

Characterizing Metrics And Outcomes Of Stress In A Climate-Sensitive Species, The American Pika, Jennifer Lee Wilkening

Ecology & Evolutionary Biology Graduate Theses & Dissertations

The American pika (Ochotona princeps) is considered a sentinel species for detecting ecological effects of climate change. Pikas are declining within a large portion of their range, but previous studies have focused only on local pika extirpation as a metric of change. This approach does not take into account the role of behavioral thermoregulation and the pika's use of microhabitats to ameliorate variations in climate. Without evidence of a direct climatic impact on pikas, studies correlating pika habitat occupancy with climate metrics provide relatively weak support for projecting effects of climate change on this species. This dissertation research focuses ...


Fine Scale Climatic And Soil Variability Effects On Plant Species Cover Along The Front Range Of Colorado, Usa, William Frank Preston Cumming Jan 2013

Fine Scale Climatic And Soil Variability Effects On Plant Species Cover Along The Front Range Of Colorado, Usa, William Frank Preston Cumming

Geography Graduate Theses & Dissertations

Fine scale studies are rarely performed to address landscape level responses to microclimatic variability. Is it the timing, distribution, and magnitude of soil temperature and moisture that affects what species emerge each season and, in turn, their resilience to fluctuations in microclimate. For this dissertation research, I evaluated the response of vegetation change to microclimatic variability within two communities over a three year period (2009-2012) utilizing 25 meter transects at two locations along the Front Range of Colorado near Boulder, CO and Golden, CO respectively. To assess microclimatic variability, spatial and temporal autocorrelation analyses were performed with soil temperature and ...