An increase in anthropogenic activities since the industrial revolution, primarily due to burning of fossil fuels and changes in land cover, has resulted in a steady increase in the global mean atmospheric CO2 concentrations. While there is unequivocal scientific evidence on global warming and its multidimensional impacts on natural and...
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Christopher J. Still
An increase in anthropogenic activities since the industrial
The topics in this dissertation are centered around the way that trees respond to environmental stress in the climates where they occur. Though forests across the planet are expected to experience change in local climate due to historic and ongoing anthropogenic greenhouse gas emissions, the effects of climate change will...
Quaking aspen (Populus tremuloides Michx) is a species with high phenotypic plasticity and a broad distribution that, in the last decade, has experienced climate stress-induced mortality called Sudden Aspen Decline (SAD). In order to help mitigate the effects of SAD in the future, we need a better understanding of aspen’s...
Recent shifts from clearcutting to partial retention harvesting on many ownerships and the importance of microclimate dynamics on biotic responses to regional climate highlight the need to understand how microclimate conditions in forest understories differ across gradients of partial overstories. This study compares below-canopy near-surface temperatures at 2cm above ground...
Grasslands account for a large proportion of global terrestrial productivity and play a critical role in carbon and water
cycling. Within grasslands, photosynthetic pathway is an important functional trait yielding different rates of productivity
along environmental gradients. Recently, C₃-C₄ sorting along spatial environmental gradients has been reassessed by
controlling for...
The forest products industry relies on the production of high-quality wood to satisfy consumer requirements. Improving wood quality requires an effective and inexpensive technique for measuring critical properties such as density and microfibril angle. An emerging technology known as near-infrared hyperspectral imaging (NIR HSI) essentially captures surface images of samples...
Quaking aspen, Populus tremuloides, has experienced severe declines in recent years in part due to the effects of changing climate and extreme drought. As the dominant deciduous tree in Western North American forests, aspen plays a critical role in forest biodiversity and ecosystem function. Therefore, the persistence of this species...
Resilient water, food, and energy management strategies for an ever-growing population and changing environment depends on our understanding of water and carbon cycles from local to global scales. Fluxes of water and carbon are coupled by photosynthesis and plant transpiration cycles the largest fraction of terrestrial water from the land...
Disease detection through traditional techniques such as scouting fields on foot, molecular assays, or morphological identification of plant pathogens is time consuming and costly. Disease diagnosis in the field can be extremely subjective, and largely depends on the experience and knowledge of pathogen identification and disease quantification. This thesis provides...
The spatial distribution of forest disturbance is commonly calculated using a satellite imagery-driven bi- or tri-temporal change analysis. Working in Colombia’s Cordillera de los Picachos National Natural Park – a region of consistent cloud cover and dramatic topographic relief – a change assessment with such infrequent observations cannot capture long-term...