Cattlemen in the southeastern United States widely plant annual ryegrass [Lolium perenne L. spp. multiflorum (Lam.) Husnot] (ARG). It is often planted earlier than the recommended window. This exposes juvenile stands to increased pressure from gray leaf spot (Pyricularia oryzae Cavara) (GLS), causing stand loss. This study was designed to screen for resistance to P. oryzae in two ARG genotypes, Vertyl and a heat-tolerant germplasm (HTARG5) with the objective of developing a crossbred population to be improved using restricted, recurrent phenotypic selection. Experiments were conducted from 2021 – 2022. Disease severity (DS) was assessed 3wk after inoculation with P. oryzae. Vertyl had a significantly lower DS in the preliminary screenings compared to the other genotypes. In experiments 3 and 4, mean DS of Vertyl, HTARG5, and Marshall was not significantly different. These results confirm Vertyl has greater resistance to GLS than HTARG5 and can be a candidate for disease resistance breeding.

The world's biodiversity is concentrated in tropical ecosystems, yet tropical forests are being converted for agriculture at a rapid rate. I evaluated the potential of an alternative coffee production system known as Integrated Open Canopy (IOC) to contribute to avian conservation. This study was conducted from 2005-2010 in the Cordillera de Tilarán, Costa Rica. My results indicate that species richness of forest-dependent birds was higher in IOC farms than in shade coffee farms, and was comparable to secondary forest sites. There was no difference in species richness of Neotropical-Nearctic migrants between IOC and shade coffee farms. Overall similarity was higher between IOC farms and primary forest than between shade coffee farms and primary forest. he golden-winged warbler Vermivora chrysoptera is a declining Neotropical-Nearctic migrant bird, yet little is known about its non-breeding season ecology and demographics. I found that golden-winged warbler abundance was highest at intermediate precipitation levels found at middle elevations (1000-1200 m) of the Pacific slope, but they were absent from the dry forests at lower elevations on the Pacific slope. Abundance peaked in forests with canopy heights of 22 m, and was positively related to the quantity of hanging dead leaves. Radio-telemetry data indicated that golden-winged warblers used microhabitat features characteristic of disturbance more frequently than expected by chance. Selection of these microhabitat features was related to their highly specialized dead-leaf foraging behavior, which may also have contributed to their high degrees of site fidelity, mixed-species flock attendance, and territoriality. These behaviors have important conservation implications because they constrain density, and thus could affect carrying capacity. Population dynamics were characterized by estimating plot-level and individual-level apparent survival and recruitment rates within and among non-breeding seasons. Both levels of analysis suggested that recruitment was too low to offset mortalities within this study area. This study indicates that increasing forest cover in tropical agricultural landscapes may be the most effective way of providing habitat for bird species of high conservation concern, including the golden-winged warbler. Integrated open canopy coffee production is one option for achieving this goal because it provides a financial incentive to protect or restore forest.

Climate changes have been observed in the Northern Hemisphere during the last century, causing a longer growing season and upslope expansion of forest, tree, and shrub limits. Here, a long-term historical perspective was used as a tool for investigating how climate change has impacted woody plants at the forest, tree, and shrub limits across the study region. For this, historical data about plant communities were used, including the position of the forest, tree, and shrub limits, gathered by the Reindeer Commission in Troms County (1914-1915). The historical data were compared to contemporary data from a re-visit study in 2022. In addition, variations in microclimatic factors were investigated by looking at the growing season length, distance to coast, slope, and aspect. Importantly, the growing season length was found to have increased across the study region with the largest increase along the coast. The increase in the growing season length led to an upslope shift in the vegetation limits, although not significantly so for the forest limit. The field layer had shifted from meadow to heath around the historical shrub limit, and non-significantly for the forest and tree limit zones, indicating that the alpine tundra is the most sensitive to the observed warming. Distance to coast and slope did not impact the shift in vegetation limits, while aspect impacted the forest limit shift. The results from this thesis indicate that future studies should expand their research beyond climate variables and explore factors such as herbivory and land use change

Human activity affects white-tailed deer (Odocoileus virginianus) movement and habitat selection during all times of the year, but knowledge is limited regarding how human risk affects white-tailed deer during the summer and winter. During spring and summer, variation in patch selection varied. Natural vegetation was selected for early in the year, with anthropogenic forages being important for deer use during the summer. During the winter, deer responded to different levels of risk. As hunter risk increased on the landscape, deer altered selection of the landscape. Deer avoided areas that were heavily used by hunters, using areas containing less hunter risk. Use of land cover classifications varied temporally, with cover selected for during the day and forage selected for at night. I have demonstrated that deer respond to human activity on the landscape, by selecting for anthropogenic foraging sources during the spring and summer and avoiding patches that contain risk.

One knowledge gap hindering prairie restoration is uncertainty about when a restored prairie communities sufficiently resemble remnant prairie. I surveyed plant communities in remnant prairies, prairies > 5 years post-restoration, and prairies ≤ 5 years post-restoration in Mississippi. Remnants had the greater species richness. Restored prairies had less cover of woody plants and forbs but greatest non-natives. Restored prairies were not similar to remnant prairies (similarity index = 28.9 - 25.9%), primarily because restored prairies had fewer prairie forbs. Thus, restoration may take decades. Transplanting locallyapted prairie forbs into restored prairies may accelerate restoration, but this has not been evaluated adequately. I transplanted a prairie forb (Liatris pycnostachya) into prepared beds, oldields, and restored prairies. Prepared beds had greater growth and seed production, but survival and flowering was high in oldields and restored prairies. Augmenting restored prairies with locallyapted forbs has promise for accelerating prairie restoration.

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