Four general post-fire successional pathways leading to a climax Engelmann spruce (Picea engelmannii Parry)/subalpine fir (Abies lasiocarpa [Hook] Nutt.) forest were identified operating on the T.W. Daniel Experimental Forest in northern Utah. These included initial colonization by seral quaking aspen (Populus tremuloides Michx.), seral lodgepole pine (Pinus contorta Dougl. ex Loud.), colonization by lodgepole pine followed by a low intensity surface fire, and immediate colonization by late successional Engelmann spruce and subalpine fir. Post-fire establishment of the late successional species occurred earliest in the Engelmann spruce/subalpine fir pathway followed by the lodgepole pine and lodgepole pine ground fire pathways, and the quaking aspen pathway . The late successional species 11 grew fastest in the Engelmann spruce/subalpine fir pathway followed by the quaking aspen, lodgepole pine, and lodgepole pine ground-fire pathways. Conceptual models were presented showing how perturbations by fire, insect epidemics, and disease could interact to influence succession and shape the subalpine landscape. The subalpine forest changes through time to facilitate different types of disturbance that have varying effects on succession. In the continued suppression of fire, species and age class diversity will be reduced and disturbances may occur that are larger and more intense than those that have occurred historically.

Presently, eleven western states and two Canadian provinces utilize sport hunting as the primary mechanism for managing cougar (Puma concolor) populations. However, the impacts of sustained harvest on population dynamics and demographic structure arc not well understood. Additionally, the lack of cost-effective enumeration techniques and strongly conflicting societal values complicate effective management of this species. Given these concerns, the primary goals of this study were (I) to determine the effects of sustained harvest on cougar populations, and (2) estimate the level and extent of cougar harvest statewide. I monitored cougar populations on Monroe Mountain in south-central Utah, and in the Oquirrh Mountains of north-central Utah from 1999 to 2003. Over this interval the Monroe population was subjected to heavy annual removals and was characterized demographically by a younger age structure. low survival and fecundity, and declining density. In contrast , the Oquirrh Mountain population was partially protected and exhibited an older age distribution, relatively high survival and fecundity, and static density. To examine the statewide distribution of sport hunting, I mapped the locations of all cougars legally harvested from I 996-200 I, and calculated harvest rates by watershed (# cougars killed I yr I I 00 km2) . Population trends derived on the st udy sites under known harvest regimes were used as benchmarks and compared with rates calculated for occupied cougar habitat across the state. This provided an index of where cougar populations were stable or declining as a result of hunting pressure. Results from this research suggest heavy, sustained harvest can have significant impacts on cougar population dynamics and demographics. Patterns of recruitment resemble a source-sink population structure due in part to spatially variable management strategies. Moreover, these results indicate during the later I 990s, most of the statewide population was exploited at levels equal to or surpass ing those measured on Monroe Mountain. Because cougar density and habitat characteristics vary across management units, the temporal scale of population recovery will most likely depend on the interaction of harvest regime, productivity of unexploited populations, and landscape connectivity.

A small mountain watershed located in the Wasatch Mountains of North Central Utah is calibrated to a lumped, deterministic simulation model which is capable of predicting daily streamflow and stream temperature. The input information required is daily precipitation and maximum and minimum air temperatures. In this study, the area of watershed modeling is reviewed in general and as it specifically applies to the study watershed. The degree of correlation between observed data and predicted output is only mediocre. The model remains unverified for streamflow prediction and is poorly verified for stream temperature.

Agroforestry as a sustainable production system has been recognized as a land use system with the potential to slow encroachment of agriculture onto forested lands in developing countries. However, the acceptance of nontraditional agroforestry systems has been hampered in some areas due to the risk-averse nature of rural agriculturalists. By explicitly recognizing risk in agroforestry planning, a wider acceptance of agroforestry is possible. This thesis consists of a collection of three papers that explore the potential of modern stock portfolio theory to reduce financial risk in agroforestry planning. The first paper presents a theoretical framework that incorporates modern stock portfolio theory through mathematical programming. This framework allows for the explicit recognition of financial risk by using a knowledge of past net revenue trends and fluctuations for various cropping systems, with the assumption that past trend behavior is indicative of future behavior. The paper demonstrates how financial risk can be reduced by selecting cropping systems with stable and/or negatively correlated net revenues, thereby reducing the variance of future net revenues. Agroforestry systems generally entail growing simultaneously some combination of plant and/or animal species. As a result, interactions between crops usually cause crop yields within systems to deviate from what would be observed under monocultural conditions, thus requiring some means of incorporating these interactions into mathematical models. The second paper presents two approaches to modeling such interactions, depending on the nature of the interaction. The continuous system approach is appropriate under conditions where yield interactions are linear between crops and allows for a continuous range of crop mixtures. The discrete system approach should be used where nonlinear interactions occur. Under this second approach, decision variables are defined as fixed crop mixtures with known yields. In the third paper, the techniques presented above were applied to a case study site in Costa Rica. Using MOTAD programming and a discrete system approach, a set of minimum-risk farm plans were derived for a hypothetical farm. For the region studied, results indicate that reductions in risk require substantial reductions in expected net revenue.

Approximately 5,000 years ago, eastern hemlock (Tsuga canadensis) experienced a sudden, rapid, range-wide decline most probably due to pest, disease, or climate change. An aphid-like defoliating insect, the hemlock woolly adelgid (Adelges tsugae), recently (1950’s) introduced to eastern North America has been spreading across the eastern United States. The adelgid attacks all size and age classes of hemlocks causing up to 95% mortality in affected stands. The potential for another range-wide hemlock decline has raised a number of concerns including the increased threat of wildfire. Altered fuel loadings in modern adelgid-affected stands and the effects of presumably similar changes in fuels and subsequently altered fire regimes following the prehistoric decline are examined. Fuels data from an adelgid-infested stand in Connecticut and an uninfested stand in Massachusetts were used to generate custom fuel models and predict fire behavior in each stand. Sediment cores were extracted from three sites in western Massachusetts and analyzed for fossil pollen and charcoal around the period of the prehistoric decline. Fossil data from two previously studied sediment cores from coastal Maine are included in the analysis. Results demonstrate a clear and highly significant increase in both fuel loadings and predicted fire behavior in the modern, adelgid-affected stand. Three of the coring sites reflect distinct, significant, short-lived increases in charcoal associated with the prehistoric decline; two do not. Results from the first three sites suggesting increased fire activity also were associated with changes in vegetation which indicate disturbance. Increased fire activity after the decline seems most pronounced in areas where fire was common before the decline. Results indicate that fire was not universally a significant factor driving post-decline succession. Research across a broader geographic area is needed to clarify the relationship between fire and hemlock following the mid-Holocene decline, but the results presented here suggest that managers of modern stands affected by the adelgid should include the possibility of intense fires as a threat to landscapes heavily affected by hemlock decline.

In 1935 I first visited the Kings Canyon area. Since then I have spent many hours wandering through the woods and over the mountains in the area around the old General Grant National Park and the country which is now included in the Kings Canyon National Park. To my knowledge, no complete flora has been made for this vicinity. I consider the following pages to be the beginning of a fascinating work. It is the beginning because this paper includes only plants with woody stems.

<p><h1>This study discusses energy and water balance in an 80-year-old deciduous Carolinian forest in the Great Lakes region in southern Ontario, Canada. The eddy covariance technique and associated meteorological and soil variables were used to make a year-round measurements of energy and water vapour fluxes from January-December,2012. This site is part of the Turkey Point Flux Station and global Fluxnet. The linear relationship between daily turbulent (sensible heat (H), latent heat (LE)) and radiative fluxes (net radiation (Rn),soil heat (G) and canopy heat storage ( S)) has a the slope of 0.75 (intercept of -15.8 Wm^-2, and a correlation coefficient, r² of 0.93) indicating a 25% deficiency in energy balance closure. The mean value of canopy albedo was 0.16 during the growing season. Maximum daily evapotranspiration (E) rate was 3.8 mm day^-1 in June, when growing is at its peak in the region. Total annual E was 400 mm, which accounted for 42% of the total annual precipitation of 950 mm. The water storage in upper soil column (1.0 m depth) was approximately 100 mm, indicating that about 450 mm of water was lost from the forest as runoff. Apart from radiation, vapour pressure deficit (D) was the dominant control on E. Maximum value of bulk surface conductance (Gs) was about 18.5 mm s^-1. Gs linearly decreased in response to increase in D. The minimum Gs values were recorded when D was maximum, i.e. 3 to 3.5 kPa. Gs also showed high sensitivity to the volumetric soil water content (ϴ), during dry periods, for example the drought event in 2012. In the growing season, the typical value of Priestley-Taylor α ranged between 0.8 to 1.2 with a maximum of 1.8, indicating a wet deciduous forest. However, the LE/Rn relationship showed a linear increase with increasing D with a low (0.26) slope, indicating a conservative response of forest E to atmospheric demand. This study provides insight into energy partitioning, the water balance and their controls in this Carolinian deciduous forest. A better understanding of evapotranspiration processes and their controls in these forests would help to better quantify water availability at local and regional scales and to evaluate the impacts of future climate change on water resources in the region.</h1></p> / Master of Science (MSc)

The purpose of this study was to determine if control charts are an effective tool to identify trends in forest growth and yield model accuracy. Accurate forest growth and yield models are important for projecting future forest composition. However, environmental factors have the potential to make forest growth models created from historic data inaccurate. Control charts in this study determine if forest growth predictions fall within confidence limits established for historic growth at a number of points in time. Two data sets were used in this study: the first was a Continuous Forest Inventory (CFI) from three tracts at the University of Tennessee Cumberland Research Station and the second data set was Forest Inventory and Analysis data collected by the U.S. Forest Service. The CFI plots represented a stand level data set measured every 5 years from 1962-1977 and revisited for a re-measurement in 2009. The FIA plots were a regional data with subsets of plots measured annually from 1999-2008. The FIA data set was limited to plots of the oak/hickory forest type from Tennessee, Alabama, and Georgia. Two forest growth and yield models were used to predict growth: (1) WinYield and (2) Forest Vegetation Simulator (FVS). The two different data sets were used with both FVS and WinYield to evaluate control charts using different models ad at different spatial and temporal scales. The data sets were also subset by site index, stand age, stocking percent, aspect, and species composition to determine if control charts could identify changes in model accuracy for forests subjected to different growing conditions. The CFI and FIA data had short growth predictions and control charts indicated that there were no trends affecting accuracy. The CFI data also had a long growth prediction of 32 years and the control charts found that the predictions using WinYield and FVS were inaccurate, indicating that there may be a trend causing inaccuracy in the model.

Historically, terrestrial food web research has focused on describing the structure of aboveground grazing webs, and determining how interactions among plants, herbivores and higher trophic levels influence primary productivity. Detrital food webs however, play a significant role in regulation of ecosystem dynamics through direct impacts on decomposition. Unraveling the complex nature of detrital food web structure is critical to developing a better understanding of ecosystem function. Therefore the primary objective of this research was to describe the structure of the leaf-litter food web in a temperate deciduous forest, with emphasis on interactions between a community of generalist predators, the forest-floor spiders, and arthropod prey. Elucidating occurrence of trophic interactions in the forest-floor food web was a formidable task due to the high diversity, small body sizes and cryptic habits of many litter-dwelling arthropods. Analysis of natural variation in consumer stable isotope ratios (δ13C and δ15N) formed the crux of this research because it simultaneously permitted quantification of the trophic positions of litterdwelling arthropods and identification of spider resources, including prey subsidies from the grazing web. A monoclonal antibody-based ELISA was employed to analyze the gut contents of spiders to quantify predation on a major arthropod taxon, the forest-floor flies. Surveys of spider distributions and prey availability in the litter layer also provided fundamental knowledge of community structure. Stable isotope analyses suggested that most spiders exhibited strong trophic connections to the detrital web, but weak links to herbivorous prey. Several lines of evidence supported a strong trophic link between large, litterdwelling collembolans (Tomoceridae) and cursorial spiders, including correlation between spider and tomocerid densities on the forest-floor, similarities in spider and tomocerid carbon signatures, and nitrogen enrichment of tomocerids relative to other prey types. Conversely, this research provided conflicting evidence regarding spider consumption of flies. Gut content assays indicated consistent predation on flies by cursorial spiders, while stable isotope models suggested that flies are likely of little importance in the spiders’ diets. This project yielded valuable insights into the role of spiders in the forest-floor food web and the potential importance of species-specific variation in prey consumption for detrital food web dynamics.

White-Nose Syndrome (WNS; Pseudogymnoascus destructans) is responsible for the regional population collapse of many cave-hibernating bat species, including the northern long-eared bat (Myotis septentrionalis), in eastern United States and Canada. I evaluated roosting behavior, habitat selection, and landscape-scale distribution of roosts of the northern long-eared bat during spring emergence and the early maternity season in Mammoth Cave National Park, Kentucky, USA, from 2015 to 2016. Logistic regression analysis comparing habitat features of roosts with random plots indicated selection of roosts reflected the costs of energetic demands by sex and reproductive status. Relative abundance of local bat species was assessed pre- and post-arrival of WNS in the Park during the summer season, with capture rates observed during the progression of WNS indicating that the fungal disease led to declines in the overall abundance of several bat species on the summer landscape, especially the northern long-eared bat. Distributional trends were quantified using spatial point pattern analysis which indicated that bats had clear roosting patterns associated with landscape level features and habitat resources. Monitoring bat populations regionally and at local scales will be imperative to helping conservation efforts for several bat species most affected by WNS.