The importance of spatial variation in abundance for the assessment of climate change impacts was examined using the North American beaver ( Castor canadensis) in Quebec as a model species. A preliminary characterization of the beavers' range edge improved the core-sampling bias and revealed that beavers are present at low densities, in shrubby riparian habitats as far north as the communities of Tasiujaq and Umiujaq. Spatial variation in beaver abundance across the province follows a roughly logistic pattern, with abundance peaking in southern Quebec, declining steeply around 49°N, and remaining uniformly low as far as 58°N. Although climate sensitivity of beaver abundance and the greatest changes in future beaver density are predicted to occur near the middle of their range, beavers are expected to occupy most of the province by 2055. These results highlight the value of incorporating density estimates from across a species' range into climate envelope models.

Sugar maple (Acer saccharum Marsh.) has experienced diebacks in many parts of its range; these declines have caused researchers to consider the many connected factors governing tree health. Altered availability of base cations due to acidic deposition and climatic extremes (drought, late winter freeze-thaw cycles) have been identified as two main causal stressors. To predict the role of climate on Ca nutrition, I investigated the relationship between the climatic factors of temperature, precipitation, water availability and windstorm on temporal changes to depth of Ca source of sugar maple. I hypothesized that the Ca uptake depth would be deeper after windstorms, or under dry or cold conditions, and shallower under warm or wet conditions. The ratio of Ca/Sr can be used to track the source of Ca. Calibration of the relationship between soil and plant Ca/Sr was done by analyzing Ca/Sr ratios in soil extracts of various strengths (H2O, NH4Cl, and ammonium EDTA) and in seedlings of sugar maple grown from natural regeneration on 37 differing sites. The relationships between soil extract Ca/Sr ratios and leaf and stem Ca/Sr ratios were linear, and the slopes of these relationships were different. These findings support the use of Ca/Sr as a tracer to Ca and they highlight the need to calibrate the technique for the plant tissue and the soil extractant used. This technique was then applied to study Ca uptake depth and its relationship with climate in the Hermine watershed, a sugar maple dominated forest in southern Quebec. The Ca/Sr was measured in soil, incremental cores of wood, and leaves. The ratio of Ca/Sr from nine soil profiles decreased with soil depth (r2 = 0.320, p<0.05), providing a signature for depth. Wood cores from ten trees were analysed in five or ten year increments from 1940 to 1999 to provide a long-term trend of Ca nutrition. Sugar maple leaves from 1995-2005 from the same 25 trees were analyzed to determine the annual dynamics of Ca uptake depth and its relationship with climate. Results suggest that the majority of tree Ca is taken from the lowest part of the rooting zone, regardless of the climatic conditions that occurred during this study, although the minor variations were related to the April temperature (r2 = 0.208, p = 0.023) and the June, July and August combined total precipitation (r2 = 0.581, p = 0.006). The effect of the windstorm on Ca uptake depth was only apparent in the area of the forest most visibly affected; Ca uptake was deeper.

This study investigated the effects of temperature and relative humidity (both controlled and natural) on the lifecyle and morphology of adults of members of the Anopheles gambiae complex in northern KwaZulu-Natal, South Africa. Laboratory investigations into the effects of simulated temperature and relative humidity regimes concentrated on seasonal differences in longevity, egg hatchability, reproductive potential and adult survivorship of An. arabiensis. Differences were found in the life table parameters when these mosquitoes were reared under conditions of seasonal temperature and relative humidity. During the cool season the lifespan and adult survivorship of mosquitoes were greater than those reared during the warm season. In summer, the egg hatchability and reproductive potential were greatest whereas in winter An. arabiensis underwent gonotrophic dissociation although these females were found to take blood meals readily. The influence of seasonal temperature and relative humidity on the body size of An. arabiensis was investigated, both in the laboratory and under field conditions. In both environments, these factors were found to significantly influence body size. In winter, there was a 13% increase in wing size compared to summer bred mosquitoes. A comparison of body size of An. arabiensis, An. merus and An. gambiae reared under laboratory conditions of seasonal temperature and relative humidity showed that the wing size of An. arabiensis was greater than that of An. merus and An. gambiae. The effect of temperature and relative humidity on morphological criteria used in species separation was also investigated. Seasonal differences in wing spot size were compared for An. arabiensis, An. merus and An. gambiae. From this investigation it was concluded that the pale and dark spots on the wing of Anopheles mosquitoes could not be used in species identification due to the large degree of inter-species overlap in the wing spot measurements. The measurement of the pale band at the junction of the 3rd and 4th tarsomere on the hind leg was also investigated for its use in species separation and were found to be useful within the An. gambiae complex. The implications of this study on the transmission and control of malaria are discussed with reference to the late season transmission during March to May that is characteristic of the region. / Thesis (Ph.D)-University of Natal, Pietermaritzburg, 1996.

Abstract available in PDF file. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2014.

Physical disturbance in the form of storm events has been implicated as a major determinant of community structure in streams. But there has been limited study of this effect on individual taxa within the communities. Such work is needed because of untested assumptions regarding the behavior of bioindicator species in these systems. Development of intricate indices of insect tolerances to organic pollution have become commonplace in environmental monitoring. However, research on the effects of natural disturbance on biological water quality assessment is lacking. Hydropsychid caddisflies are relatively intolerant to organic pollution and the United States Environmental Protection Agency has outlined the use of these organisms and others as an indication of clean water. If a species is recorded as absent from samples when it is present but hidden, this false negative would bias the water quality assessment. I tested hypotheses regarding the behavior of hydropsychid caddisflies facing increased discharge, and the effect of stream size on the magnitude of this phenomenon.Three sites along the West Fork of the White River, Indiana USA were studied during nine storms between 2001 and 2004. Stratified sampling from the upper 15 cm of substrate prior to and just after a storm, and again following reestablishment of normal flow, revealed alterations of hydropsychid distributions. During storms all but one species sought refuge in the hyporheic zone at depths dependent upon storm intensity. The possibility that poor water quality resulting from increased discharge caused the hydropsychid behavior was refuted by chemical analysis. Family level biotic index (FBI) data demonstrated that increased discharge results in a reduction of stream FBI values. These results indicate that high intensity storm events influence biological monitoring and should be factored into sampling protocol. / Department of Biology

Spatial distribution of species and thus the composition of deciduous forests are expected to change in response to global climatic warming. Climate-growth response algorithms in forest simulation models that represent the influence of climate on tree growth are based on the geographic range limits of a species. These models assume that temperature limitations control the latitudinal range boundaries for tree species in the eastern United States, and that water limitations control the western range boundary. This study investigated spatial variation of tree-growth responses to historical variations in climate using tree-ring data for Quercus rubra L. from 71 study sites across latitudinal and longitudinal temperature and precipitation gradients in eastern North America. Correlation analyses were used to identify significant site-specific associations between radial growth indices and 130 climate variables for the common time interval 1930-1980. Geographic information systems (GIS), and Mantel and partial Mantel spatial correlation analyses were used to map, identify, and measure spatial associations between oak sensitivity to climate and regional climate patterns to test the hypothesis that climate controls the spatial distributions of species range limits.Seasonal climate variables exhibited the strongest correlations with radial growth most consistently across the 71 study sites. However, spatial patterns in regional climate were only weakly associated with spatial variation in red oak sensitivity to climate variables. Contrary to expectations, correlations between red oak radial growth indices and temperature variables at northern and southern sites were not significant, failing to support the hypothesis that latitudinal range limits are defined by temperature effects on mature tree growth. High early growing season temperature reduced growth mostly at sites in the southwest region, which concomitantly experienced high inter-annual variability in soil moisture. Increased early growing season site water balance and precipitation was associated with greater radial growth in the western third of red oak's range, partially supporting the hypothesis that the western range limit is defined by limited water availability. These results indicate that climate only partially determines range limit locations; thus model projections may exaggerate forest responses to climate change. / Department of Biology

This research was initiated to develop an understanding of the differential radial-growth response of mature mountain hemlock (Tsuga mertensiana) trees located along a line of latitude in northwestern British Columbia. Increment core samples were collected from mountain hemlock stands located at five high-elevation sites between the Queen Charlotte Islands and Smithers. Tree ring-width index chronologies were compared to historical precipitation and air temperature data from four climate stations, as well as the El Nino Southern Oscillation and the Pacific Decadal Oscillation. No two mountain hemlock stands had the same growth response to monthly air temperature and precipitation, indicating that the trees are responding to site-specific limiting factors. The response to El Nino Southern Oscillation events was consistent along the transect, while the response to Pacific Decadal Oscillation phase changes was greatest at coastal sites and decreased towards the interior.

The objectives were to induce and study the effects of adverse climatic conditions on sugar maple. Two different snow removal treatments were applied over the winter period of 1990-91 and a tarpaulin treatment was applied over the summer period of 1991 to a sugar maple stand in the Morgan Arboretum. The complete snow removal and tarpaulin treated trees showed decreased leaf water potential and increased peroxidase activity over the growing season. Foliar Ca was reduced in the two different snow removal treatments early in the growing season while foliar N was reduced in the complete snow removal trees late in the growing season. Soil NO$ sb3 sp-,$ K$ sp+$ and Mn$ sp{2+}$ was elevated in the complete and partial snow removal, and tarpaulin treatments at various times throughout the growing season. The snow removal treatments affected both water and nutrient status as well as tree health.

Commercial office building occupants are a significant consumer of electricity, and they subsequently contribute a significant amount of greenhouse gases into the environment in the process. An opportunity exists to improve the energy efficiency in existing buildings, and the Energy Star certification program provides both tools to do so and an independent verification of a building's superior energy efficiency. However, only 16% of metro Atlanta's office space has achieved this certification. The intent of the research was to identify the current state of energy efficiency in buildings, and to identify potential obstacles to obtaining the Energy Star certification. Towards this goal, secondary research was conducted among prominent academic journals, as well as numerous professional and governmental organizations and publications. Primary research was conducted through an online survey of Facility Managers, Property Managers, and Building Engineers of Energy Star office buildings and comparable non-Energy Star office buildings in the metro Atlanta area. The survey was conducted mostly using closed-ended questions using a Likert scale so as to provide a basis for statistical analysis among responses, and open-ended questions were also included to identify the current state of energy efficiency practices. The research identified three areas which hold statistically significant differences between Energy Star and directly comparable buildings. An analysis also determined that building age does seem to play a role in the building representatives' responses. Four conclusions were found regarding characteristics of Energy Star buildings themselves. The research also identified five conclusions regarding the expected result when pursuing the Energy Star certification. These conclusions include the best method to achieve the Energy Star certification, the expected energy savings, the expected time spent to achieve the certification, the expected cost to achieve the certification, and the main reasons to recertify the building. Finally, this research highlights innovative practices in other states and cities, such as financial incentives and legislation which require commercial buildings to obtain a building rating. Such innovative practices are currently not employed in the Atlanta metro area, but would be beneficial to both the Atlanta area and individual buildings.

Thesis (M.S.)--University of Hawaii at Manoa, 2007. / Includes bibliographical references (leaves 69-71). / x, 71 leaves, bound ill., maps 29 cm