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Full-Text Articles in Life Sciences
Individual And Population Responses To Hydrologic Variability In A Headwater Stream Salamander, Madaline Cochrane
Individual And Population Responses To Hydrologic Variability In A Headwater Stream Salamander, Madaline Cochrane
Graduate Student Theses, Dissertations, & Professional Papers
Understanding how organisms respond to environmental variability is a central goal in ecology – a goal made even more pressing by the herculean challenge global climate change presents to all organisms. Climate change is increasing the frequency and intensity of floods and droughts, which will likely have disproportionate effects on freshwater organisms. Many stream-associated species have multi-stage life histories. However, we lack an empirical understanding of life history and movement responses of these organisms to hydrologic disturbances, and how these responses may influence demographic rates. In my dissertation, I used a combination of growth, developmental, movement, and demographic data to …
Impacts Of Climate And Wildfire On Western Larch Regeneration, Spencer T. Vieira
Impacts Of Climate And Wildfire On Western Larch Regeneration, Spencer T. Vieira
Graduate Student Theses, Dissertations, & Professional Papers
Fire plays a critical role in forests of the western United States (US), but as wildfire and climate deviate from historical patterns, increasing fire activity may significantly alter forest ecosystems. To understand the impacts of changing climate and wildfire activity on conifer forests, we studied the impact of wildfire and annual post-fire climate on western larch (Larix occidentalis) regeneration. We destructively sampled 1651 seedlings from 57 sites within 32 fires that burned at moderate or high severity from 2000-2015 in the northwestern US. Using dendrochronological methods, we estimated germination years of seedlings to calculate annual recruitment rates. We …
How Aquatic Insects Mitigate Temperature-Oxygen Challenges Via Behavioral, Morphological, And Physiological Plasticity, Jackson H. Birrell
How Aquatic Insects Mitigate Temperature-Oxygen Challenges Via Behavioral, Morphological, And Physiological Plasticity, Jackson H. Birrell
Graduate Student Theses, Dissertations, & Professional Papers
How do organisms respond to environmental challenges and to environmental change? These questions occupy a central place in ecology and answering them will help us to understand why species live where they do, how organisms are affected by human activities, and, ultimately, how to choose among alternative conservation strategies. These questions are difficult, however, for two reasons. First, environmental challenges often involve multiple, interacting stressors. Second, individual responses can be modified by behavioral, morphological, and physiological plasticity. My dissertation investigates how interactions between temperature and oxygen influence the performance and survival of aquatic insects and how plasticity allows individuals to …
A Biophysical Approach To Modeling Elevational Range Shifts In Colorado Mammal Communities, Ryan T. Mahar
A Biophysical Approach To Modeling Elevational Range Shifts In Colorado Mammal Communities, Ryan T. Mahar
Graduate Student Theses, Dissertations, & Professional Papers
Species geographic ranges are shifting in the face of contemporary climate warming, and documenting range shifts is crucial to our understanding of the underlying drivers mediating movement in geographic range limits. Studies on elevational range shifts with climate change are beginning to accrue within the literature, though observed shifts are idiosyncratic and difficult to predict. Some species may respond to warming temperatures by shifting their range limits upslope, where temperatures are cooler owing to the adiabatic lapse rate. However, species may also respond to warming temperatures in an elevation-dependent manner: if changes in snow depth expose overwintering organisms to colder …
Heat For The Masses: Thermal Ecology Of The Western Tent Caterpillar, Victoria Dahlhoff
Heat For The Masses: Thermal Ecology Of The Western Tent Caterpillar, Victoria Dahlhoff
Graduate Student Theses, Dissertations, & Professional Papers
A unique feature of some gregarious, colonial insects is their ability to create external structures that alter environmental conditions for the entire (often family) group. A combination of physical alteration of local microhabitats and behavioral thermoregulation allows many of these animals to actively control their body temperatures, which allows them to regulate energy use and metabolism in variable thermal environments. Here I describe mechanisms of microhabitat modification and thermal regulation in the western tent caterpillar, Malacosoma californicum pluviale. Tent caterpillars build communal silk tents, whose temperatures can rise substantially above ambient air temperature. I experimentally manipulated colony sizes and examined …
Limited Evidence For Co2-Related Growth Enhancement In Northern Rocky Mountain Pinus Contorta Populations: Trends In Growth And Intrinsic Water-Use Efficiency Across Climate Gradients, Charlotte C. Reed
Graduate Student Theses, Dissertations, & Professional Papers
Forests sequester large amounts of carbon annually; however, the degree to which enhanced forest productivity is due to more conducive climate or CO2 fertilization remains uncertain. Increasing atmospheric CO2 may enhance photosynthesis and/or decrease stomatal conductance thereby enhancing intrinsic water use efficiency (iWUE). While increasing iWUE has been observed in most trees globally, this increase does not necessarily translate into greater growth. This study aims to evaluate whether responses of radial growth and iWUE to increasing CO2 vary across climatic gradients. To investigate interactions between climate and CO2 and their impacts on tree physiology and growth, …