Forest Sciences Commons^™

Evidence Of Competitive Release Following Overstory Mortality In A Semi-Arid Piñon-Juniper Woodland, Corrie D. Gonzalez

Biology ETDs

Extreme temperatures and severe drought events have led to widespread tree mortality worldwide. In semi-arid regions of the Southwest United States, these events pose a significant threat to piñon-juniper (PJ) woodlands. We studied the effects of piñon and juniper mortality on the growth and physiology of existing saplings in PJ woodlands by analyzing water status, photosynthetic activity, and tissue chemistry to gain insights into these impacts. Juniper saplings exhibited improved water status and water use efficiency in response to overstory mortality, whereas piñon saplings did not. Additionally, both piñon and juniper saplings exhibited increased photosynthetic rates, increased photosynthetic capacity, and …

Competition And Herbivory Influence The Survival, Growth, And Physiology Of Native Tree Seedlings In The Kentucky Inner Bluegrass Savanna-Woodland, James D. Shaffer

Theses and Dissertations--Biology

Terrestrial plant communities are shaped by competition for resources, herbivory, and abiotic processes. Savanna systems represent a dynamic coexistence of contrasting life forms (grasses and trees) shaped by competition and disturbance. The Kentucky Inner Bluegrass Savanna-Woodland (KIBSW) is described as an open woodland of shade intolerant species; however, climatic, and edaphic conditions can support closed-canopy forest. After European pioneer settlement (c1750-1800), over 99% of “savanna-woodlands” have been lost. KIBSW remnants are experiencing a recruitment failure, leading to a dominance shift in tree communities. I researched how tree-grass competition and mammalian herbivory influence KIBSW regeneration and maintenance. The KIBSW does not …

Conifer Encroachment And Removal In A Northern California Oak Woodland: Influences On Ecosystem Physiology And Biodiversity, Gabriel S. Goff

Cal Poly Humboldt theses and projects

Oregon white oak (Quercus garryana) woodlands across their range are becoming increasingly threatened by encroaching Douglas-fir encroachment (Pseudotsuga menziesii) as a result of fire exclusion. Using water potential (Ψ), stomatal conductance (g_s), xylem water stable isotopes (dD), and three metrics of biodiversity, this study investigates the effects of conifer encroachment and removal at the ecosystem-scale. The study was set in an Oregon white oak woodland in northern California and compared three levels of encroachment before and after conifer removal. Findings indicate that heavily encroached stands have the least amount of water stress and gas …

Drought And Freezing Vulnerability Of The Isolated Hybrid Aspen Populus X Smithii Relative To Its Parental Species, P. Tremuloides And P. Grandidentata, Nicholas J. Deacon, Jake J. Grossman, Jeannine Cavender-Bares

Aspen Bibliography

Aim

We assessed the vulnerability of an isolated, relictual Pleistocene hybrid aspen population of conservation interest (Populus x. smithii ) and the nearest populations of its parent species (Populus grandidentata and Populus tremuloides ) to springtime post‐bud break freezing and growing season drought stress. Response to these stressors in the three taxa was compared in terms of avoidance and tolerance.

Location

North American Midwest; USA.

Methods

Unique genets from the hybrid Niobrara River population and from the two parental populations were propagated in a common garden from rhizome cuttings. We tracked their phenology before and after bud break …

Effects Of Reproductive Condition, Roost Microclimate, And Weather Patterns On Summer Torpor Use By A Vespertilionid Bat, Joseph S. Johnson, Michael J. Lacki

Forestry and Natural Resources Faculty Publications

A growing number of mammal species are recognized as heterothermic, capable of maintaining a high-core body temperature or entering a state of metabolic suppression known as torpor. Small mammals can achieve large energetic savings when torpid, but they are also subject to ecological costs. Studying torpor use in an ecological and physiological context can help elucidate relative costs and benefits of torpor to different groups within a population. We measured skin temperatures of 46 adult Rafinesque's big-eared bats (Corynorhinus rafinesquii) to evaluate thermoregulatory strategies of a heterothermic small mammal during the reproductive season. We compared daily average and minimum skin …