Dissertations / Theses on the topic 'Climatic factors'

American Viticultural Areas (AVAs) are susceptible to small variations in climate and microclimates and are found within a narrow latitudinal range of prime climate conditions. These AVAs are geographically determined based on the best soil, climate, precipitation and temperature combinations for specific winegrape regions. As climate change continues to alter the local weather and the greater climate region of the Western United States, winegrape growing regions in Oregon are being affected. In an effort to determine what the pattern of change is, and compare previous studies of climate change using climate indices, a comparative study based in part on prior research was conducted. Using 800 meter resolution Parameter-elevation Regressions on Independent Slopes Model (PRISM) climate datasets, four individual climate indices were analyzed for statistical correlation with the climate data. These climate indices are: growing degree-days (GDD), the average growing season temperatures (GST), Huglin Index (HI) and the biologically effective degree-day (BEDD). Based on currently available data for this research, these climate indices were statistically analyzed during the years 2000 to 2010. A further avenue of research included a statistical analysis of the reported winegrape production, although this data was available only at an aggregated county-level. Results show that all four climate indices exhibit statistical significance, although the inclusion of the winegrape production data exhibited no statistical significance for many of the analyses, most likely due to subjective and aggregated data, few did result in significance with the climate indices. The research discussed here confirms the accuracy of the four climate indices and suggest that a longer time frame, coupled with less aggregated and subjective winegrape production data could produce interesting results in future research on the results of climate indices in winegrape growing regions.

Mapping and explaining the distribution of vegetation helps land managers to make systematic conservation planning decisions. This is typically achieved using models that correlate the distribution of species with environmental factors, and can predict the vegetation at unsurveyed locations. These Species Distribution Models (SDMs) have numerous unresolved issues, but serve as a useful first-pass approximation for planning purposes.This thesis investigates some of the uncertainties of SDMs, including the impact of data accuracy, the incorporation of spatial processes, the evaluation of alternative models, and the benefits and challenges of producing models at the landscape scale. The research was conducted on the Illawarra Escarpment, 80 km south of Sydney, Australia (34.4 oS, 150.9 oE). The escarpment contains a north-south trend in eucalypts (Eucalyptus spp.) that cannot be explained in terms of elevation or geology. It also exhibits a patchy distribution of rainforest communities, some unique to the Illawarra. It is not known which environmental factors determine the distribution of either the eucalypts or rainforest species, or how they may respond to a changing climate.Species distributions are sensitive to the accuracy of data used, and yet many models only use elevation as a surrogate for temperature, or use simple elevation sensitive interpolations from weather stations. I collected hourly temperature data from 40 sites on the Illawarra Escarpment, and investigated whether elevation was an adequate surrogate for temperatures in this landscape. I then investigated whether temperature surfaces could be improved by considering other topographic and geographic factors, including exposure to wind, distance to coast, radiation, and the average conditions in the surrounding neighbourhood. Elevation was well correlated with moderate seasonal temperatures (e.g. summer minima and winter maxima), but was poorly correlated with the extreme temperatures (summer maxima, winter minima) that are physiologically limiting for many species. Using neighbourhood influences, exposure to wind and distance to coast improved the accuracy of temperature surfaces, and increased the explanatory performance of vegetation models. I concluded that elevation was not always an adequate surrogate for temperature. Temperatures are also affected by other topographic and geographic factors, and these should be considered when developing models for systematic conservation planning activities.Species distribution models are typically based solely on niche factors. Where spatial processes are included, it is typically by employing autologistic regression, or other techniques that use survey data as a predictor. This precludes the models being used to make predictions in times or places where survey data is unavailable, and reduces ecological explanation because it is an interpolation technique. I used neighbourhood (contextual) indices based on environmental factors as an alternative method to overcome these problems. I demonstrate that contextual indices improve SDMs over purely niche-based models, and are capable of predicting unknown populations in unsurveyed areas. I conclude that contextual indices have numerous advantages over autologistic regression, and can capture a continuum between niche and dispersal limited species.Models that predict how species will respond to climate change either use coarse-scale climate surfaces, or idealised predictions of uniform warming. These methods may dramatically over-estimate extinction risk because they neglect fine-scale variations in warming, and refugia where species can persist despite unfavourable regional conditions. I created fine-scale estimates of warming by combining 35 years of Bureau of Meteorology observations with one year of intensive fine-scale temperature monitoring. I found that warming was greatest at inland locations, at lower elevations, away from streams, and at sites exposed to hot, dry northwesterly winds. As species are biased in the geographic and topographic positions they occupied, some species have experienced more warming than others and are at greater threat from climate change. I concluded that it was important to continue developing methods to downscale coarse-grained climate surfaces, and suggest that the accuracy of this process could be improved by using a range of topographic factors.There are many methods for selecting predictors in SDMs, and the competing models often make highly variable predictions. I addressed this uncertainty by comparing the performance of models with and without a given environmental factor. I found that there was relatively strong support for the geology and winter minimum temperature predictors, as well as predictors based on contextual indices, as there was a significant drop in model performance when these predictors were excluded. In contrast, there was less support for summer maximum temperature, as other temperature predictors could combine to produce similar model performance. Model performance varied more between models for different species than between different predictor combinations for the same species. I concluded that it was inappropriate to assess models based on subjective benchmarks, such as an AUC of more than 0.7. A comparison between competing models for the same species gives a better indication of the validity of the model building procedure.The results of this research provide important insights into the benefits and challenges of creating SDMs at the landscape scale (extent of 10–200 km). It is a major challenge to obtain spatially and thematically accurate environmental predictors and biotic data at this scale, and studies should include the collection of data to ensure models are adequate. Landscapes will not have as much environmental variation as coarse-scale models, and this will limit the ability to transfer the models to new study areas. However, there are a number of benefits that justify these studies. Producing accurate temperature surfaces at the landscape scale will result in less pseudoreplication and less predictor colinearity. This will improve the robustness of models. Landscape scale studies also allow modellers to capture fine-scale refugia, and this will improve the accuracy of climate change predictions. Finally, many ecological processes operate at a scale that is too fine to be detected with coarse-scale models. Landscape scale models may be the only alternative to detect these processes. There is no optimal scale for SDMs, however, and a future challenge is to better integrate coarse and fine-scale models to make more ecologically robust predictions.

viii, 21 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.
To determine the relative effects of rapid climate change on selection and drift in small populations, nine northern populations of the pitcher-plant mosquito, Wyeomyia smithii, were exposed to directional selection equivalent to 180 years of climate change, while control populations were maintained in their native climate. After three years, fitness had declined in the selected but not the control populations, indicating an adverse effect of climate change. When both selected and control populations were then reared in the selected climate, they showed no difference in fitness, indicating no genetic response to selection. Importantly, however, fitness was negatively correlated with accumulated inbreeding in both control and selected populations, pointing out that the effects of inbreeding and drift exceeded those of selection imposed by rapid climate change. Therefore, small northern populations at expanding edges of species' distributions should be most vulnerable to continued climate change.
Committee in Charge: Dr. William Bradshaw, Chair; Dr. Christina Holzapfel; Dr. Nathan Tublitz

Thesis (MScAgric)--University of Stellenbosch, 2001.
ENGLISH ABSTRACT: During Holocene times a considerable deposit of barn owl pellet material accumulated in the Hot Pot Cave at De Hoop Nature Reserve on the southern coast of the Western Cape Province, South Africa. An excavation of this accumulation has yielded information on barn owl prey species over the past some two millennia. Four distinct layers were excavated and radiocarbon-dated to AD 381, AD 615, AD 991 and AD 1417. The micromammalian cranial contents of these layers were compared to material from two pellet collections that represent modem bam owl predation at De Hoop (AD 2000). Comparisons were made from three perspectives: (1) physical size measurements of certain cranial parameters, (2) micromammal community species composition and (3) community structure indices, such as the Shannon-Wiener diversity index, Simpson's diversity index and the species equitability index. By extrapolating from known ecological distribution information of the relevant prey species, these data were used to recreate the local climate at the time of the accumulation of the layers. The results were compared to other palaeoclimate models for the region as a test of validity. It was found that the lower two layers of the sequence represented mild conditions with possibly more grass than in recent times, while the upper layers represented cool weather with a possible increase in scrub. AD 381 was found to be somewhat dry and mild, AD 615 to be the wettest level and possibly milder than AD 381, AD 991 to be the coolest of all the levels and dryest of the ancient levels, AD 1417 to be somewhat cool and probably drier than AD 615, but wetter than AD 381, and AD 2000 to be the mildest and dryest of all levels, with the artificial influence of nearby agricultural activities evident.
AFRIKAANSE OPSOMMING: Tydens die Holoseen tydperk het 'n relatief groot hoeveelheid nonnietjie-uil bolusmateriaal versamel in Hot Pot Grot in die De Hoop Natuurreservaat aan die Wes-Kaapse suidkus, Suid- Afrika. Opgrawings van hierdie bolusversameling het waardevolle en insiggewende inligting aandie lig gebring rakende nonnetjie-uil prooi tydens ongeveer die afgelope tweeduisend jaar. Vier defnitiewe lae is opgegrawe en deur radiodatering is die lae se datums vasgestelop 381, 615, 991 en 1417 n.e. Deur gebruik te maak van kraniale kriteria. is die mikrosoogdier inhoud van die opgrawings vergelyk met dié van twee bolusversamelings wat die huidige uilprooi (2000 n.Ci) in De Hoop verteenwoordig. Die vergelykings is op drie maniere getref: (1) fisiese grootternates van sekere kraniale parameters, (2) species-samestelling van die mikrosoogdiergemeenskap en (3) gemeenskap-struktuur indekse nl. die Shannon-Wiener diversiteitsindeks, Simpson se diversiteitsindeks en die species-gelykheid indeks. Deur ekstrapolasie vanaf bekende ekologiese verspreidingsinligting rakende die betrokke species, is hierdie data gebruik om die klimaat van daardie tydperke te herskep op 'n streeksbasis en vergelyk met ander paleoklimaat-modelle om die geldigheid daarvan te beproef. Die resultate het getoon dat die onderste (oudste) twee lae warmer toestande met moontlik meer gras verteenwoordig, terwyl die boonste twee lae koeler weer met moontlik meer bosse verteenwoordig. Daar is verder gevind dat 381 n.e. redelik droog en warm was, 615 n.e. die natste laag en moontlik warmer as 381 n.e., 991 n.e. die koudste van al die lae en droogste van die grot-lae, 1417 n.e. redelik koel en moontlik droëer as 615 n.e., maar natter as 381 n.e., en 2000 n.C. die warmste en droogste van al die lae, met kunsmatige invloed van nabygeleë landbou aktiwiteite.

Eight glaciers, covering an area of 1.63 km2, reside on the northern and northeastern slopes of the Goat Rocks tallest peaks in the Cascades of central Washington. At least three glacial stands occurred downstream from these glaciers. Closest to modern glacier termini are Little Ice Age (LIA) moraines that were deposited between 1870 and 1899 AD, according to the lichenometric analysis. They are characterized by sharp, minimally eroded crests, little to no soil cover, and minimal vegetation cover. Glacier reconstructions indicate that LIA glaciers covered 8.29 km2, 76% more area than modern ice coverage. The average LIA equilibrium line altitude (ELA) of 1995 ± 70 m is ~150 m below the average modern ELA of 2149 ± 76 m. To satisfy climate conditions at the LIA ELA, the winter snow accumulation must have been 8 to 43 cm greater and mean summer temperatures 0.2 to 1.3 ºC cooler than they are now. Late Pleistocene to early Holocene (LPEH) aged moraines are located between 100 and 400 m below the LIA deposits. They have degraded moraine crests, few surface boulders, and considerable vegetation and soil cover. Volcanic ashes indicate LPEH moraines were deposited before 1480 AD while morphometric data suggest deposition during the late Pleistocene or early Holocene. The average LPEH ELA of 1904 ± 110 m is ~ 240 m and ~90 m below the modern and LIA ELAs, respectively. The climate change necessary to maintain a glacier with an ELA at that elevation for LPEH conditions requires the winter accumulation to increase by 47 to 48 cm weq and the mean summer temperature to cool by 1.4 to 1.5 ºC. Last glacial maximum (LGM) moraines are located more than 30 km downstream from modern glacial termini. They are characterized by hummocky topography, rounded moraine crests, complete vegetation cover, and well developed soil cover. Moraine morphometry, soil characteristics, and distance from modern glacial termini indicate that deposition occurred at least 15 ka BP during an expansive cooling event, the last being the LGM. The LGM ELA of 1230 m is ~920 m below the modern ELA. The climate change necessary to maintain a glacier with an ELA at that elevation for LGM conditions requires the mean summer temperature to cool by 5.6 ºC with no change in precipitation.

Pneumonia, one of the leading causes of children's morbidity and mortality, can be affected by climate change and socio-environmental factors. The thesis applied spatial and temporal models to quantify the effects of climate factors on childhood pneumonia and identify the potential high-risk areas of childhood pneumonia in Bangladesh. The findings of the thesis will inform policymakers about the magnitude of climate variability on childhood pneumonia and aid policymakers provide appropriate health interventions that consider climate variability. The thesis findings also have great potential for developing climate-based early warning framework for childhood pneumonia in Bangladesh.

Thesis (MSc)--University of Stellenbosch, 2000.
ENGLISH ABSTRACT: The development time, survival and fecundity of Trichogrammatoidea cryptophlebiae Nagaraj a, an egg parasitoid of false codling moth, Cryptophlebia leucotreta Meyr., on . citrus were determined at 15,20,25 and 30°C. Using these values the intrinsic rate of increase (rm), mean generation time (T) and net replacement rate (Ra) were estimated at the respective temperatures. In addition, the data were used to estimate the minimum temperature required for development. The rmincreased from 15 (0,042) to 20°C (0,088) and then gradually decreased from 25 (0,069) to 30°C (0,012). The Ra was highest at 20°C (3,116 females/female), followed by 15°C (2,607 females/female), 25°C (1,894 females/female) and 30°C (1,092 females/female). T decreased as temperature increased from 7 days at 30°C to 22,79 days at 15°C. The estimated minimum temperature for development was 7,65°C which implies that this wasp should be able to survive and reproduce under normal winter conditions in the Western Cape.
AFRIKAANSE OPSOMMING: Die ontwikkelingstyd, oorlewing en vrugbaarheid van Trichogrammatoidea cryptophlebiae Nagaraj a, 'n eierparasitoied van valskodlingmot, Cryptophlebia leucotreta Meyr., op sitrus is bepaal by 15, 20, 25 en 30oe. Hierdie waardes is gebruik om die intrinsieke tempo van vermeerdering (rm), die gemiddelde generasietyd (T) en die netto vervangingstempo (Ro) te bepaal by die betrokke temperature. Die data is verder gebruik om die minimum temperatuur vir ontwikkeling te bepaal. Die rm waarde het toegeneem van 15°e (0,042) tot by 200e (0,088) en afgeneem van 25°e (0,069) tot 300e (0,012). Die Ro was die hoogste by 200e (3,116 wyfies/wyfie), gevolg deur 15°e (2,607 wyfies/wyfie), 25°e (1,894 wyfies/wyfie) en 300e (1,092 wyfies/wyfie). T het afgeneem met 'n toename in temperatuur en was 7 dae by 300e en 22,79 dae by 15°e. Die beraamde minimum temperatuur vir ontwikkeling was 7,65°e wat aandui dat hierdie wespe kan oorleef en voortplant by normale wintertoestande in die Wes-Kaap.

Agriculture is a climate sensitive sector whether it changes moderately and slowly or radicallyand rapidly. Many studies that focus on the vulnerability of agriculture, use climate scenariosand crop models to assess the potential impacts. This study seeks to identify (1) farmers‘awareness and perceptions of climate variability and change; (2) the types of adjustments theyhave made in their farming practices in response to these changes (farm responses, adaptivestrategies); and (3) other external factors (government policies, social, technological andeconomic conditions) that have significant impact on the farming activities.The results indicate that climate change and variability already have and will have mostlynegative impacts on agriculture. Prolonged dry spells and heat in the summer, less summerrain combined with higher temperatures, more heavy rainfall, more forest or grass fires andextreme weather: drought, flood, storms have been identified as highest climatic burdens toagriculture. An advanced start of the growing season is the the only truly positive change forthe majority of farmers. Apart from that several non-climatic factors were identified assignificant, among them political: high level of bureaucracy, lack of public trust in socialinstitutions, political instability; economical: incentives, for example tax exemption orreduction, access to subsidies and funds, economic growth and development, long-lastingeconomic recession; technological and infrastructural: access to advanced technologies,infrastructure and settlement development and poor road and railroad system; and social:population migration within Europa, ageing of population and population decrease. Thesesocio-economic factors play significant roles in overcoming the risks and building adaptivecapacity. This study shows that a variety of strategies and methods have been applied toreduce the vulnerability. Most often it is a farm level managerial decision, like, adjustedtiming of farm operations, changed crop variety and types, reduced number of livestock,improved technological base or increased income by off farm jobs.Finally we can conclude that even though individual farms have capacity to reducevulnerability, one must not underestimate the role of government and industry to decrease thedamages, take advantage of opportunities or cope with consequences. Farmer decision tomake changes in farming activities is rarely based on one risk alone.

Sesame (Sesamum indicum L.) is a tropical oilseed found growing in the mid-altitude ($<$1700 m.a.s.l.) regions of Ethiopia. Recently, there has been an attempt by settler farmers from the Ethiopian plateau to expand sesame cultivation in the low altitude areas ($<$800 m.a.s.l.). A genotype-environment interaction study on sesame lines developed through progeny selection originating from a bulk of landraces was carried out at six environments in Ethiopia. The environments selected were believed to provide a wide variation in temperature (altitude), moisture and soil. The objective of the study was, therefore, to select a line or lines widely adaptable over these environments for variables seed yield, oil and protein content as well as fatty acid composition. Two statistical methods, namely, the regression model and the procedural approach of superiority measure were used to estimate line adaptability. Several lines were identified which were adapted over the six environments while others were specifically adapted to low- or high-yielding environments. Lines showing wide adaptation for one variable were not always widely adapted for others. In addition, the two parametric statistics used to analyze the data did not always agree for each variable.

A single site Neyman-Scott point process model of rainfall, with convective and stratiform cells (Cowpertwait, 1994; 1995), has been employed to generate synthetic rainfall inputs to a rainfall runoff model. The time series of the potential evapotranspiration (ETp) demand has been represented through an AR(n) model with seasonal component, while a simplified version of the ARNO rainfall-runoff model (Todini, 1996) has been employed to simulate the continuous discharge time series. The model incorporates a saturation excess runoff production component, and a routing component based on a network width function and a linear parabolic transfer function. All these models have been parameterised in a realistic manner using observed data and results from previous application, to obtain ‘reference’ parameter sets. Continuous hourly time series of rainfall and potential evapotranspiration, of length 10000 years, have been generated using the reference parameter sets for both models. They have been then used as inputs to the rainfall runoff model, and an hourly time series of discharges has been generated from which the annual maximum flood peaks have been extracted and plotted against the Gumbel variate. Subsequently, perturbations to the model parameters have been made through two approaches: a) the analysis initially was performed by perturbing the parameters one-at-a-time and the sensitivities of the generated annual maximum rainfall and flood frequency curves (unstandardised, and standardised by the mean) have been assessed graphically and with the assistance of several statistics (a) of the annual maximum rainfall and peak flood values and (b) of the soil moisture content at the storm arrival time. Overall, the sensitivity analysis described in this research suggests that the soil moisture regime, and, in particular, the probability distribution of soil moisture content at the storm arrival time, can be considered as a unifying link between the perturbation to the several parameters and their effects on the standardised and unstandardised ffcs, thus revealing the physical mechanism through which their influence is exercised. However, perturbations to the parameters of the linear routing component affect only the unstandardised ffc; b) the second approach which can be considered as a full sensitivity analysis, the effect of model parameters on the ffc has been assessed through an analysis of variance (ANOVA) of the results obtained from a formal experimental design, where all the parameters are allowed to vary simultaneously, thus providing deeper insight into the interactions between the different factors. This approach allows a wider range of climatic and basin conditions to be analysed and suggests that further investigations are needed to understand better the factors affecting the links between climate and basin characteristics and the ffc properties. Finally, as a complementary study, the simulation modelling approach is evaluated using several properties of the streamflow and annual maximum flood.

Doutoramento em Biologia
A compreensão dos impactes das alterações climáticas é fundamental para a gestão a longo do prazo dos ecossistemas estuarinos. Esta compreensão só poderá ser efectiva considerando a variabilidade climática natural e o papel relativo das intervenções antropogénicas nestes ecossistemas. Assim, a presente dissertação analisa a influência das alterações climáticas e pressões antropogénicas na qualidade da água e dinâmica ecológica da Ria de Aveiro com base numa abordagem integrada, que combinou a análise de séries temporais dos últimos 25 anos e a modelação numérica de elevada resolução de cenários futuros de alterações climáticas e intervenções antropogénicas. A componente de modelação de qualidade da água e ecológica foi melhorada a vários níveis. A análise de sensibilidade do modelo 3D hidrodinâmicoecológico ECO-SELFE aplicado à Ria de Aveiro e a revisão das constantes de semi-saturação para absorção de nutrientes pelo fitoplâncton contribuíram para a precisão e robustez das aplicações. A concentração do fitoplâncton foi significativamente influenciada pelas taxas de crescimento do fitoplâncton e de mortalidade e excreção do zooplâncton, e apresentou uma sensibilidade reduzida à variação das constantes de semi-saturação na gama identificada para as diatomáceas. O acoplamento do ECO-SELFE a um modelo de campo próximo e a integração do ciclo do oxigénio aumentaram a sua capacidade de representação dos processos e das escalas espaciais relevantes. A validação do ECO-SELFE foi realizada com base num conjunto de campanhas específicas realizadas no canal de Mira. Os padrões espaciais e temporais observados para as várias variáveis (clorofila a, nutrientes, oxigénio dissolvido, salinidade, temperatura da água, correntes e níveis) foram simulados com erros menores ou semelhantes aos obtidos neste tipo de aplicações. A análise dos padrões de variabilidade espacial e temporal da qualidade da água e ecológica na Ria de Aveiro a diferentes escalas, efectuada com base nos dados históricos de 1985 a 2010 complementados pelas campanhas realizadas, sugeriu uma influência combinada da variabilidade climática e das acções antropogénicas. Os cenários futuros de alterações climáticas e intervenções antropogénicas simulados evidenciaram uma influência mais significativa das alterações climáticas quando comparadas com os efeitos das acções antropogénicas analisadas. As variações mais significativas são previstas para os cenários de subida do nível do mar, seguidos dos cenários de alterações dos regimes hidrológicos, evidenciando o papel da circulação (maré e caudal fluvial) no estabelecimento da qualidade da água e dinâmica ecológica na laguna. Para os cenários de subida do nível do mar são previstos decréscimos significativos da clorofila a e dos nutrientes a jusante e nas zonas intermédias do canal, e um aumento significativo da salinidade a montante. Estas alterações poderão favorecer modificações da composição e distribuição das comunidades, afectando a cadeia alimentar e causando uma progressão para montante de espécies marinhas. Os resultados sugerem ainda que os efeitos poderão ser mais significativos em estuários pouco profundos.
Understanding the impacts of climate change is essential to ensure the longterm management of estuarine ecosystems. This understanding will only be reliable if the systems’ natural variability and the relative role of anthropogenic pressures are considered. Thus, this thesis evaluates the influence of climate change and anthropogenic pressures on the water quality and ecological dynamics of the Aveiro lagoon based on an integrated approach, combining the analysis of long time series from the past 25 years and high-resolution numerical modelling of future scenarios of climate change and anthropogenic interventions in the lagoon. The water quality and ecological modelling component was improved at several levels. The sensitivity analysis of the 3D hydrodynamic-ecological model ECOSELFE applied in the Aveiro lagoon and the review of the half-saturation constants for nutrients uptake by phytoplankton contributed to the precision and robustness of the applications. Phytoplankton concentration was significantly influenced by the phytoplankton growth and zooplankton mortality and excretion rates, and presented a low sensitivity to the half-saturation constants variation within the range reviewed for diatoms. ECO-SELFE’s coupling to a near field model and its extension to the oxygen cycle increased the model’s ability to represent the relevant processes and spatial scales. ECO-SELFE validation was achieved based on a set of specific field campaigns performed along the Mira channel. The spatial and temporal patterns observed for the measured variables (chlorophyll a, nutrients, dissolved oxygen, salinity, water temperature, currents and water levels) were reproduced by the model with errors smaller or similar to the ones achieved in this type of applications. The analysis of the spatial and temporal patterns of variability of the water and ecological quality in the Aveiro lagoon at different scales, based on historical data from 1985 to 2010 complemented by the campaigns performed, suggested a combined influence of the climatic variability and anthropogenic interventions. Future scenarios of climate change and anthropogenic interventions simulated revealed a larger influence of climate change when compared with the analysed anthropogenic actions. The most important variations from the reference scenario are predicted for the sea level rise scenarios, followed by the changes in the hydrological regimes scenarios, putting in evidence the main role of circulation (tide and river flow) in establishing the water quality and ecological dynamics in the lagoon. A significant decrease of chlorophyll a and nutrients is predicted in the downstream and middle areas of the channel due to sea level rise, while a significant salinity increase is predicted upstream. These changes may promote modifications in the communities’ distribution and composition, affecting the food web and promoting a progression further upstream of the marine species. Results also suggest that the identified effects may be more important in shallow estuaries.

Thesis (MScAgric)--University of Stellenbosch, 2005.
ENGLISH ABSTRACT: Quality of certain Leucospermum and Leucadendron cultivars after approximately 21 days shipping has been reported to be substandard due to ‘drying out’ of leaves and, in the case of Leucadendrons, involucral leaves. The nature of the symptoms of this ‘drying out’ and the conditions under which they form, viz. long exposures to low temperatures, has led us to hypothesize that these are symptoms of chilling injury (CI). Chilling injury, as far as we are aware, has not been documented on Leucospermums or Leucadendrons. Typical CI symptomology is discussed and shown for Leucospermum ‘Gold Dust’, ‘High Gold’ and ‘Succession’ and for Leucadendron ‘Chameleon’, ‘Laurel Yellow’ and ‘Safari Sunset’. The nature of CI symptoms for Leucospermums and Leucadendrons was generally membranous breakdown that manifested in some cases as a ‘water soaked’ appearance which, at a more advanced stage, was generally visible as ‘dried out’ patches on the leaves. In the case of the Leucadendrons CI was also visible on the immature involucral leaves which are more sensitive to chilling conditions than mature leaves. Dark discoloration of especially immature involucral leaves is also a symptom of CI. As water uptake of shoots with chilling injury is hindered the styles of the Leucospermums wilt. As can be expected, the lower the temperature below the threshold temperature and the longer the exposure the more severe the symptoms. CI was recorded on cut flower shoots of Leucospermum ‘Gold Dust’, ‘High Gold’, ‘Rigoletto’, ‘Succession’ and ‘Vlam’ after 21 and 24 days storage at 1ºC. After 24 days storage the chilling injury was more severe than after 21 days storage in most cases. Each cultivar was pulsed with 5 ml per stem of a 2% (w/v) sugar solution of either lactulose, sucrose, glucose, fructose or mannose before storage. After storage, CI was recorded on day 0, 3, 7 and 10 of the vase phase. Of the cultivars tested ‘Vlam’ and especially ‘Rigoletto’ were more prone to chilling injury development. ‘High Gold’ and ‘Vlam’ shoots were pulsed with 0 (control), 1.5, 3 or 4% (w/v) solutions of either mannose or fructose. The best control of CI for both cultivars was achieved with 1.5% (w/v) solution. Lower concentrations of mannose and fructose were tested on ‘High Gold’ shoots, with a 1% (w/v) solution giving the best control for both. At high concentrations signs of toxicity became evident directly after pulsing. ‘High Gold’ shoots were pulsed with 1% (w/v) solutions of mannose and fructose and sugar analyses were performed on shoots at different stages of storage and after 10 days in the vase. A slight increase in mannose and fructose was detectable in the stems of the shoots directly after pulsing but not in the leaves or the inflorescences. This is due to the low concentrations being used. The levels of all the carbohydrates decreased during the 21 days storage and more so during the vase phase of the flowering shoots. The fact that such low concentrations were effective in controlling chilling injury suggests that the sugars may have an effect other than on the osmotic potential. Cut ‘flower’ shoots of Leucadendron ‘Chameleon’, ‘Laurel Yellow’ and ‘Safari Sunset’ were stored for 14, 21 and 28 days, at 1º, 3º and 5ºC and CI development recorded during the subsequent 10 day vase phase. ‘Laurel Yellow’ and ‘Safari Sunset’ showed signs of chilling injury on the leaves after 28 days storage at 3ºC or lower and ‘Safari Sunset’ stored for 21 days developed chilling injury during the vase phase. Immature involucral leaves were more sensitive to chilling injury than leaves. CI increased with longer exposure times and lower storage temperatures for all three cultivars evaluated. ‘Chameleon’ was the most chilling tolerant of the cultivars up to 21 days. At 5ºC chilling injury was low irrespective of cold storage duration but longer exposures to 1º and 3ºC resulted in increased chilling injury development during the vase phase. All three cultivars were pulsed with 5 ml per stem of a 1% (w/v) solution of lactulose, sucrose, glucose, fructose or mannose and stored for 14, 21 and 28 days at 1ºC. The sugars reduced chilling injury on the leaves for ‘Safari Sunset’ when stored for 28 days and, to a lesser extent, in ‘Chameleon’. The sugars failed to reduce chilling injury of the involucral leaves of ‘Chameleon’ and ‘Laurel Yellow’ whereas there was some control especially after 28 days for ‘Safari Sunset’. In some cases the sugar pulse exacerbated chilling injury. Chilling injury generally increased rapidly after storage during the first three days in the vase and then at a lower rate for the next seven days. Leucadendron ‘Chameleon’, ‘Laurel Yellow’ and ‘Safari Sunset’ ‘cut flower’ shoots were pulsed with a 1% (w/v) glucose solution. Expressed on a dry weight basis, an increase in glucose concentration was not detected. The reduction in chilling injury of leaves by a sugar pulse is speculated, as for the Leucospermums, to be as a result of their presence in the apoplast and not the symplast and that their presence there protects the membranes against chilling conditions in some way.
AFRIKAANSE OPSOMMING: Die kwaliteit van sekere Leucospermum en Leucadendron kultivars na ongeveer 21 dae verskeping is waargeneem as substandaard as gevolg van die uitdroog van blare en, in die geval van Leucadendrons, die ‘involucral’ blare. Die aard van die simptome van hierdie uitdroging en die toestande waaronder dit plaasvind nl. lang periodes van blootstelling aan lae temperature, het ons tot die hipotese gebring dat hierdie simptome van koueskade is. Sover as wat ons bewus is, is koueskade nog nie gedokumenteer op Leucospermums of Leucadendrons nie. Tipiese koueskade simptomologie word bespreek en gewys vir Leucospermum ‘Gold Dust’, ‘High Gold’ en ‘Succession’ en vir Leucadendron ‘Chameleon’, ‘Laurel Yellow’ en ‘Safari Sunset’. Die koueskade simptome vir Leucospermums en Leucadendrons was oor die algemeen membraan afbraak wat ‘n water deurdrenkte voorkoms tot gevolg gehad het wat in ‘n meer gevorderde stadium sigbaar was as uitgedroogde kolle op die blare. In die geval van Leucadendrons was koueskade ook sigbaar op die onvolwasse ‘involucral’ blare wat meer sensitief is vir koue toestande as volwasse blare. Donker verkleuring van veral onvolwasse ‘involucral’ blare is ook ‘n simptoom van koueskade. Aangesien wateropname van stele met koueskade verhinder word, verwelk die ‘styles’ van die Leucospermums. Soos verwag kan word hoe laer die temperature onder die drempel temperatuur en hoe langer die blootstelling, hoe meer ernstig die simptome. Koueskade is aangeteken op gesnyde blomstele van Leucospermum ‘Gold Dust’, ‘High Gold’, ‘Rigoletto’, ‘Succession’ en ‘Vlam’ na 21 en 24 dae opberging by 1°C. Na 24 dae opberging was die koueskade meer ernstig as na 21 dae opberging in meeste gevalle. Elke kultivar het 5ml per steel van ‘n 2% (g/v) suiker oplossing van laktolose, sucrose, glucose, fruktose of mannose voor opberging opgeneem. Na opberging is koueskade aangeteken op dag 0, 3, 7 en 10. Van die kultivars wat getoets is, was ‘Vlam’ en veral ‘Rigoletto’ meer geneig tot koueskade ontwikkeling. ‘High Gold’ en ‘Vlam’ stele is geplaas in oplossings van 0 (kontrole), 1.5, 3 of 4 % (g/v) oplossings van mannose of fruktose. Die beste beheer van koueskade vir beide kultivars is deur die 1.5 (g/v) oplossing behaal. Laer konsentrasies van mannose en fruktose is getoets op ‘High Gold’ stele met ‘n 1% (g/v) mannose oplossing wat die beste beheer gegee het. Met hoë konsentrasies het tekens van toksisiteit sigbaar geword direk na opneem van die oplossing. ‘High Gold’ stele is geplaas in 1% (g/v) oplossings van mannose of fruktose en suiker analises is uitgevoer op stele by verskillende stadiums van opberging en na 10 dae in die vaas. ‘n Effense toename in mannose en fruktose is waargeneem in die stele van die blomme direk na opname van die oplossing, maar nie in die blare of die blomme nie. Dit is as gevolg van die lae konsentrasies wat gebruik is. Die vlakke van al die koolhidrate het afgeneem gedurende die 21 dae opberging en nog meer so gedurende die vaas periode van die blommende stele. Die feit dat sulke lae konsentrasies effektief is in die beheer van koueskade dui daarop dat die suikers ‘n effek het anders as op die osmotiese potensiaal. Snyblomme van Leucadendron ‘Chameleon’, ‘Laurel Yellow’ en ‘Safari Sunset’ is opgeberg vir 14, 21 en 28 dae, by 1º, 3º en 5°C en koueskade ontwikkeling is aangeteken gedurende die opvolgende 10 dae vaas periode. ‘Laurel Yellow’ en ‘Safari Sunset’ het tekens gewys van koueskade op die blare na 28 dae opberging by 3°C of laer en ‘Safari Sunset’ opgeberg vir 21 dae het koueskade ontwikkel gedurende die vaas periode. Onvolwasse ‘involucral’ blare was meer sensitief vir koueskade as die blare. Koueskade het toegeneem met langer blootstellingstye en laer opbergins temperature vir al drie kultivars geëvalueer. ‘Chameleon’ was die mees koueverdraagsaam van die drie kultivars tot op 21 dae. By 5°C was laag ongeag van die koue opberging tydperk, maar langer blootstellings aan 1º en 3°C het gelei tot toename in koueskade ontwikkeling gedurende die vaas periode. Al drie kultivars is voorsien met 5ml per steel van ‘n 1% (g/v) oplossing van lactulose, sucrose, glucose, fruktose of mannose en opgeberg vir 14, 21 en 28 dae by 1°C. Die suikers het koueskade verminder op die blare van ‘Safari Sunset’ wanneer opgeberg vir 28 dae en, tot ‘n mindere mate, in ‘Chameleon’. Die suikers het egter nie koueskade verminder van die ‘involucral’ blare van ‘Chameleon’ en ‘Laurel Yellow’ nie, waar daar egter wel in ‘n mate beheer was veral na 28 dae vir ‘Safari Sunset’. In sommige gevalle het die voorsiening van suiker die koueskade vererger. Koueskade het oor die algemeen vinnig toegeneem na opberging gedurende die eerste drie dae in die vaas en dan teen ‘n laer tempo vir die volgende sewe dae. Leucadendron ‘Chameleon’, ‘Laurel Yellow’ en ‘Safari Sunset’ snyblom stele is voorsien van ‘n 1% (g/v) glukose oplossing. Uitgedruk op ‘n droëmassa basis is ‘n toename in glukose konsentrasie nie waargeneem nie. Die afname in koueskade van blare deur die voorsiening van ‘n suiker oplossing is gespekuleer vir die Leucospermums, om ‘n resultaat te wees van hulle teenwoordigheid in die apoplas en nie die simplas nie, en dat die teenwoordigheid daar die membrane op ‘n manier beskerm teen koue toestande.

Drought is among the costliest natural hazards developing slowly and affecting large areas, which imposes severe consequences on society and economy. Anthropogenic climate change is expected to exacerbate drought in various regions of the globe, making its associated socioeconomic impacts more severe. Such impacts are of higher concern in Africa, which is mainly characterized by arid climate and lacking infrastructure as well as social development. Furthermore, the continent is expected to experience vast population growth, which will make it more vulnerable to the adverse effects of drought. This study provides the first comprehensive multi-dimensional assessment of drought risk across the African continent as a function of hazard, vulnerability, and exposure. A multi-model and multi-scenario approach is employed to quantify drought hazard using the most recent ensemble of regional climate models and a multi-scalar drought index. Moreover, a rigorous framework is proposed and applied to assess drought vulnerability based on various sectors of economy, energy and infrastructure, health, land use, society, and water resources. Drought risk is then projected for different population scenarios and the changes of drought risk and the role of each component are investigated. In addition, the impacts of climate change on heat-stress mortality risk is assessed across the Middle East and North Africa. The results indicate vast increase for the projected drought risk with varied spatiotemporal patterns. Population growth and climate change will significantly escalate drought risk, especially in distant future. Therefore, climate change mitigation and adaptation planning as well as social development strategies should be carried out immediately in order to reduce the projected adverse risks on human life and society.

Ecophysiology studies are needed to predict plant responses in relation to climate change. Variations in salinity and inundation are expected to influence the survival and distribution of salt marsh. The following species were chosen to study as they occur in most South African salt marshes and are representative of different tidal ranges; namely Triglochin buchenaui (lower intertidal), Bassia diffusa (upper intertidal succulent) and Limonium linifolium (upper intertidal non-succulent). To simulate climate change conditions as predicted for South Africa, a 3 x 5 controlled experiment of three inundation levels (tidal, submerged and drought) and five salinity levels (0, 8, 18, 35, 45 ppt) was conducted for each species. This resulted in 15 treatments per species. Plant responses were measured over a three month period. Triglochin buchenaui showed significant variation in height (7.57 ± 0.5 to 29 ± 1.55 cm, p < 0.005, DF = 55) with optimum growth at 0 ppt under tidal conditions; leaf area increments and relative growth rates which decreased with increasing salinity under all inundation states. There was almost a cessation of growth under submergence which reduces the plant’s regeneration potential under these conditions. Proline accumulation (1.84 ± 0.23 to 3.36 ± 0.38 mg l-1), response of photosynthetic pigments and electrolyte leakage (8.17 ± 0.80 to 38.36 ± 7.42 percent) were fundamental to osmotic and membrane response regulation. Plants survived in all inundation states at salinity up to 45 ppt, but the optimum range was 0 to 18 ppt, and best water state was the tidal condition. Viable rhizomes were produced under drought conditions. Bassia diffusa (Thunb.) Kuntze plants under submergence died within one month, irrespective of the salinity. Optimum growth occurred in plants of the tidal treatment at 18 ppt, and reduced with increased salinity and drought conditions. Plants in the tidal treatments were more succulent than the drought-treated plants. There was reduced leaf mass and high anthocyanin concentrations in drought-treated plants and these effects increased with salinity. Soil and leaf water potential were positively correlated with anthocyanin concentration in leaves and stems, suggesting anthocyanin accumulated in response to drought and could be an adaptation to lower the plant’s water potential under drought conditions. A shift of anthocyanin from leaves to stems was found in drought-treated plants, and this possibly enables the maximization of photosynthesis in leaves, to complement its role in osmotic balance and photo-protection. Growth of Limonium linifolium showed that the plant was tolerant to a wide range of salinity under both tidal and drought conditions, but was susceptible to complete submergence, with high membrane damage even in tidal-treated plants. Plants died within 2 weeks of complete submergence. Results further indicated that L. linifolium tolerates extreme drought by accumulating large quantities of proline and oxalic acid, which consequently lowers its water potential for uptake of soil water of high salinity. Excess salts were excreted through salt glands. This is an important adaptation for a plant that thrives in a highly variable saline habitat Further investigation of submergence effects on upper intertidal species using B. diffusa showed three key stages in the response. A drop in chlorophyll a+b within 6 hours (4.2 ± 0.2 to 2.4 ± 0.3 mg l-1) with a corresponding increase in carotenoid concentration (0.6 ± 0.1 mg l-1) indicated an immediate response to submergence. Oxalic acid concentration was highest on Day 4 (13.6 mM) as opposed to control levels, indicative of its role in submergence tolerance, thus Day 4 may be the peak of positive acclimation. The third phase was marked by a sharp increase in electrolyte leakage to 47.5 ± 2.6 percent on Day 10, from 9.4 ± 1.4 percent on Day 7, with a corresponding decrease in total dissolved solutes between Days 7 and 10. Results suggest that oxalic acid accumulates under submergence possibly as a stabilizing osmolyte. The threshold for tolerance of the species under submergence is 7 days with membrane damage thereafter. Bassia diffusa would not survive prolonged submergence (> 7 days) but could survive submergence of short duration (< 7 days) through continuous underwater photosynthesis, accumulation of osmolytes such as oxalic acid and carotenoid, and maintenance of relative water content and succulence within control levels. When considered together, results showed that the two upper intertidal species were sensitive to waterlogging and would not survive complete submergence, whereas the lower intertidal species could in addition to its natural range, thrive in conditions typical of the upper intertidal range, namely prolonged dry conditions and high sediment salinity. These results have important implications for the future management of salt marshes under predicted climate change conditions. In permanently open South African estuaries, a landward migration of salt marsh will be possible if coastal squeeze is limited and the rate of landward recruitment is on par with sea level rise. In this case salt marsh species would retain their current zonation while shifting inland. Increased sea storms and saltwater intrusion could lead to high salinity concentration in the sediment and significantly reduce growth of salt-sensitive plants. In estuaries that are temporarily open to the sea, reduced freshwater inflow will result in an increase in mouth closure, high water levels, prolonged submergence, and consequently die back of salt marsh vegetation. On the other hand increased abstraction and drought would result in low water levels and high sediment salinity which would decrease growth and survival of salt marsh. This research has provided new knowledge on the ecophysiology of salt marsh plants which can be used to predict the responses of plants to climate change.

Environmental control of interactions between larval fish and their prey, and the potential influence of this relationship on fish feeding and recruitment, were assessed using empirical models developed using data drawn from the literature and developed in field studies. Ingestion rates of larval fish in laboratory and natural environments were found to differ in relation to food density. In laboratory studies, larvae show a strong functional response to prey density. Larvae situated in situ consume food at much higher races than would be predicted from laboratory studies and these rates are independent of prey density at known in situ densities. This discrepancy between laboratory and field feeding rate-food density relationships can be partly explained by the in situ contribution of small-scale turbulence to predator-prey encounter rates. Field studies of the influence of wind on nearshore hydrography showed that wind-induced upwelling generated favorable combinations of nutrients, light, and small-scale turbulence for production by phyto- and zooplankton. The distribution of microplankton $(<$80 $ mu$m) that resulted from these upwelling episodes was quantitatively described by the cumulative longshore wind velocity during the summer months. Microplankton abundance was greatest within 4 km of a major spawning site for capelin, Mallotus villosus, an economically and ecologically important forage species in the north Atlantic Ocean. Interannual variability in the intensity and frequency of upwelling-favorable winds was positively and significantly correlated with recruitment levels in the NAFO 2J3K capelin population. A new recruitment forecasting model, using an upwelling-related wind index as an input, explained more of the variance in capelin recruitment than did a previously published model. These results suggest that larval capelin are more likely to be food-limited in years when wind conditions are unfavorable for upwelling, and that recruitment in this fi

Living specimens of Cryptomeria japonica D.Don var. radicans Nakai collected in western Japan were analyzed to evaluate the research potential of this tree species for future development of dendrochronology and dendroclimatology in Japan. A sufficiently strong correlation of tree growth with climatic factors was obtained in the residual chronology in which the variance due to autocorrelation was removed. It was also revealed that regional average climatic data are strongly correlated with tree growth. Thus, Cryptomeria japonica appears to have a promising potential for chronology- building and climatic reconstruction in Japan.

This paper presents the synthesis of all the response functions computed on Cedrus atlantica (Endl.) Carrière in Morocco. More than a thousand tree-ring width series collected in 40 sites have been used. At every site, a distinction has been made between young adult trees and old adult trees. Response functions have been calculated on the mean raw ring widths by using the multiple linear regression model of Guiot (Guiot et al. 1982). Among the variables selected to determine the response of Cedrus to climate, the precipitation of autumn and winter and the temperature of January, April, August and September play the leading part in explaining the ring-width variations.

Thesis (DPhil)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: This study is informed by both the deficit/positivist and contextual/critical models for doing public understanding of science (PUS) research and seeks to investigate factors that influence the perceptions, beliefs and attitudes towards climate change in Malawi. Previous research on the public understanding of climate change conducted in the United States of America (USA) and Europe suggest that people‘s beliefs, perceptions and attitudes do influence support for both voluntary and policy initiatives to address climate change and adaption to it. However, it is equally important to understand the factors that influence public perceptions, beliefs and attitudes towards climate change. An investigation into these factors provides an understanding and appreciation of the contextual issues related to the public assimilation and renegotiation of climate change information, as well as the support or rejection of initiatives aimed at addressing climate change. Sub-Saharan African countries are most vulnerable to the effects of climate change because their national economies and populations depend on rain-fed agriculture. Malawi is no exception. The majority of the Malawian population (at least 85%) live in rural areas and depend on subsistence, rain-fed agriculture for their livelihood, and are therefore more vulnerable to climate change. Furthermore, Malawi‘s economy is agro-based (agriculture comprises about 36% of the Gross Domestic Product (GDP), 85% of exports earnings and 84% of total employment). On the basis of these facts, I hypothesised that the perceptions, beliefs and attitudes of Malawians towards climate change are influenced by a wide range of factors, including the impact of climate change on livelihoods. More specifically, I proposed that more rural inhabitants than urban residents were likely to agree that their livelihood has been negatively affected by climate change, and would also be more willing to take voluntary action to address climate change. Upon performing chi-square analyses of the responses, the results indicate that: (i) significantly more rural (91%) than urban inhabitants (51%) agree that their livelihood has been negatively affected by climate change, and (ii) significant higher proportions of the rural population have at some point taken voluntary action to address climate change Multinomial logistic regression models predicted the perceptions, beliefs and attitudes of Malawians towards climate change. The results show that location is the only predictor of whether an individual would agree that his/her livelihood has been negatively affected by climate change or not. Rural inhabitants are 6.5 times more likely than urban residents to agree that their livelihood has been negatively affected by climate change. Location is also a predictor of the belief that climate change and its impact is the will of God; the belief that the solution to climate change rests with God; and how certain or uncertain a person is regarding the effects of climate change. Binary logistic regression results show that location is also the strongest predictor of whether an individual would take a voluntary action to address climate change or not. Rural inhabitants are 2.3 times more likely than urban residents to take voluntary action to address climate change. Besides place of residence, other predictors of perceptions, beliefs and attitudes towards climate change are: level of education (predictor of three outcome variables, namely: how certain or uncertain a person is about the causes of climate change; whether an individual believes that climate change and its impact is the will of God or not; and whether an individual believes that the solution to the problem of climate change rests with God or not); environmental groups and institutions of learning as sources of information about climate change (predictors of how certain or uncertain a person is about the causes of climate change, and whether a person believes that climate change and its impact is the will of God or not, respectively); and the trustworthiness of village headmen as a source of information about climate change (predictor of whether an individual will believe that climate change and its impact is the will of God or not; and whether an individual will take personal initiative to address climate change). These findings affirm the hypothesis that the impact of climate change on livelihoods of Malawians living in rural locations influences their perceptions, beliefs and attitudes towards climate change. Additionally, the findings suggest that public education about climate change remains key to promoting understanding of climate change. The Government of Malawi and non-governmental organisations have to take up this challenge of educating the Malawian public about climate change, particularly those living in rural locations. However, public education of climate change in Malawi demands that we also take into account the contextual factors that influence Malawians‘ perceptions, beliefs and attitudes towards climate change. For future research, the study suggests that more research in Sub-Saharan Africa is warranted to unearth the contextual factors that influence the public understanding of climate change.
AFRIKAANSE OPSOMMING: Hierdie studie inkorporeer insigte uit onderskeidelik die tekortskietende/positiwistiese en kontekstuele/kritiese modelle rakende die openbare verstaan van wetenskapsnavorsing, in ‘n poging om die faktore wat die persepsies, oortuigings en houdings teenoor klimaatsverandering in Malawi beïnvloed te ondersoek. Vorige navorsing oor die openbare begrip van klimaatsverandering – wat in die Verenigde State van Amerika (VSA) en Europa uitgevoer is – dui daarop dat individuele persepsies, oortuigings en houdings ‘n invloed uitoefen op die ondersteuning vir beide vrywillige sowel as beleidsinisiatiewe in klimaatsverandering. Dit is egter van groot belang om die faktore wat openbare persepsies, oortuigings en houdings teenoor klimaatsverandering beïnvloed te verstaan. ʼn Ondersoek na hierdie faktore verskaf begrip sowel as waardering vir die kontekstuele kwessies wat verband hou met die openbare assimilasie en ―heronderhandeling‖ van inligting oor klimaatsverandering. So ‘n ondersoek dra ook by tot ‘n verduideliking waarom voorgestelde klimaatsveranderingsinisiatiewe òf verwerp òf ondersteun word. Lande in sub-Sahara Afrika, waaronder Malawi, is baie kwesbaar vir die gevolge van klimaatsverandering as gevolg van die aard van hul ekonomieë en die samelewing se afhanklikheid van nie-besproeiingslandbou. Die Malawiese bevolking is grotendeels landelik (ten minste 85%) en maak staat op nie-besproeiingsbestaansboerdery, wat hulle dus meer kwesbaar maak vir die gevolge van klimaatsverandering. Malawi se ekonomie is boonop landbou-gedrewe: landbou dra by tot ongeveer 36% van die BBP, tot 85% van inkomste uit uitvoere en tot 84% van totale indiensnemingsgetalle. Gegewe hierdie feite is my hipotese dat die persepsies, oortuigings en houdings van Malawiërs teenoor klimaatsverandering deur talle uiteenlopende faktore beïnvloed word, waaronder die impak van klimaatsverandering op hul daaglikse bestaan. Die hipotese suggereer verder dat meer landelike inwoners, in teenstelling tot stedelike inwoners, geneig sal wees om saam te stem dat hul bestaan negatief deur klimaatsverandering beïnvloed word, en derhalwe ook ‘n groter gewilligheid sal openbaar tot vrywillige optrede wat klimaatsverandering aanspreek. Chi-kwadraat analises wat op die opnameresponse uitgevoer is, dui daarop dat (i) meer landelike (91%) as stedelike (51%) inwoners saamstem dat hul bestaan negatief deur klimaatsverandering beïnvloed word en dat (ii) ʼn beduidende hoër persentasie landelike inwoners op een of ander stadium vrywillig teen klimaatsverandering opgetree het. Multinomiale logistiese-regressiemodelle is gebruik om die persepsies, oortuigings en houdings van Malawiërs teenoor klimaatsverandering te voorspel. Die resultate toon dat ligging die enigste betekenisvolle voorspeller is in die uitkoms of ʼn individu saamstem dat sy/haar bestaan negatief deur klimaatsverandering beïnvloed word of nie – dit is 6.5 keer meer waarskynlik dat landelike as stedelike inwoners sal saamstem dat hul bestaan negatief deur klimaatsverandering beïnvloed word. Ligging dien ook as ʼn betekenisvolle voorspeller in drie verdere uitkomste, naamlik die oortuiging dat klimaatsverandering en die impak daarvan die wil van God is, die oortuiging dat die oplossing vir klimaatsverandering by God berus en hoe seker of onseker ʼn individu van sy/haar oortuiging is met betrekking tot die gevolge van klimaatsverandering. Volgens ‘n binêre logistiese-regressieanalise is ligging ook die sterkste voorspeller of ʼn individu vrywillig sal optree om klimaatsverandering aan te spreek, al dan nie. Dit is 2.3 keer meer waarskynlik dat landelike inwoners, in teenstelling met stedelike inwoners, vrywillig sal optree om klimaatsverandering aan te spreek. Agesien van ligging het die volgende ook na vore getree as bykomende voorspellers van individue se persepsies, oortuigings en houdings teenoor klimaatsverandering: (i) vlak van opvoeding (voorspeller van drie uitkomste-veranderlikes: hoe seker of onseker ʼn persoon is oor die oorsake van klimaatsverandering; of ʼn persoon glo dat klimaatsverandering en die gevolglike impak die wil van God is al dan nie; en of ʼn individu glo dat die oplossing vir klimaatsverandering by God berus al dan nie), (ii) die twee bronne van inligting rondom klimaatsverandering, naamlik omgewingsgroepe en opvoedingsinstellings, wat dien as voorspellers van hoe seker of onseker ʼn individu is oor die oorsake van klimaatsverandering, en of ʼn persoon glo dat klimaatsverandering en die gevolglike impak die wil van God is of nie; en (iii) die geloofwaardigheid van stamhoofde as ʼn bron van inligting oor klimaatsverandering (voorspeller van of ʼn persoon sal glo dat klimaatsverandering en die gevolglike impak die wil van God is of nie en of ʼn individu persoonlike inisiatief aan die dag sal lê om klimaatsverandering aan te spreek). Die bevindinge van die studie bevestig die voorgestelde hipotese dat die impak van klimaatsverandering op die bestaan van Malawiërs wat in landelike gebiede woon, ook hul persepsies, oortuigings en houdings teenoor klimaatsverandering beïnvloed. ʼn Verdere bevinding is dat openbare opvoeding oor klimaatsverandering ʼn sleutelrol in die bevordering van die begrip oor klimaatsverandering speel. Die uitdaging rus op die skouers van die Malawiese regering en nie-regeringsorganisasies om die Malawiese publiek, en veral diegene wat in landelike gebiede woon, oor klimaatsverandering op te voed. Die voorgestelde organisasies sal hulself egter nie van hul taak kan kwyt indien daar nie ʼn begrip is van die faktore wat Malawiërs se persepsies, oortuigings en houdings teenoor klimaatsverandering beïnvloed nie. Die studie beveel aan dat meer navorsing in sub-Sahara Afrika onderneem behoort te word om kontekstuele faktore wat die openbare begrip van klimaatsverandering beïnvloed, te identifiseer.

Doutoramento em Biologia
Apesar dos estudos de microcosmo e mesocosmo terem um papel importante no procedimento de registo dos pesticidas, a extensão pelos quais os resultados dos diferentes estudos de modelos de ecossistema poderem ser extrapolados para outros casos é ainda um assunto de debate. Esta tese pretende contribuir para a discussão sobre a influência local, temporal e dos factores metodológicos nos resultados dos estudos do microcosmo. Para este efeito, foram efectuados estudos do microcosmo com água doce em condições experimentais distintas e os efeitos do tratamento e o destino comparados com os reportados em experiências similares. As experiências com pequenos microcosmos laboratoriais com aplicações únicas de clorpirifos, linurão e carbendazim nem sempre previram as respostas exactas, tal como observado em experiências com modelos de ecossistema em larga escala. Uma vez que os sistemas utilizados eram fechados e não continham sedimento nem macrófitas, os pesticidas eram mais persistentes e os valores de toxicidade calculados tornaram-se mais comparáveis com os estabelecidos nas experiências com exposição prolongada. As implicações e as recomendações para a metodologia de estudos de avaliação de risco aquático são discutidos na secção discussão geral. Uma experiência do microcosmo na Tailândia, lidando com múltiplas aplicações de clorpirifos, conduziu à conclusão que o tempo de aplicação tem uma elevada influência nos efeitos do insecticida nas comunidades de água doce. Isto é explicado em relação às fases da população das comunidades de zooplâncton no momento da aplicação. Os valores de toxicidade calculados nos estudos do microcosmo tropical depois de aplicações únicas de pesticida estavam dentro da gama (clorpirifos e carbendazim) ou mais elevado (linurão) que os reportados em estudos temperados. Assim, estes resultados suportam o uso de dados de toxicidade de estudos de ecossistemas modelo levados a cabo em zonas temperadas para a avaliação de risco ambiental em países tropicais.
Although micro- and mesocosm studies play an important role in the registration procedure of pesticides, the extent by which the results of different model ecosystem studies may be extrapolated to one another is still a matter of debate. This thesis aims to contribute to the discussion concerning the influence of spatial, temporal and methodological factors on the outcome of microcosm studies. For this purpose, freshwater microcosm studies were carried out under different experimental conditions and fate and treatment effects compared with those reported in similar experiments. Small indoor microcosm studies with single applications of chlorpyrifos, linuron and carbendazim did not always predict the exact responses as was observed in larger-scale model ecosystem studies. Since closed systems were used that did not contain sediment and macrophytes, pesticides were more persistent and calculated toxicity values were therefore generally more comparable with those reported in studies with long-term exposure. Implications and recommendations for the methodology of aquatic risk assessment studies are discussed in the general discussion section. A microcosm study in Thailand dealing with multiple chlorpyrifos applications led to the conclusion that the time of application has a large influence on the effects of the insecticide on freshwater communities. This is explained in relation to the population phase of zooplankton communities at the time of application. Threshold values calculated in tropical microcosm studies after single pesticide applications were well in range (chlorpyrifos and carbendazim) or higher (linuron) than those reported in temperate studies. These findings thus support the use of toxicity data from model ecosystem studies carried out in the temperate zone for the environmental risk assessment in tropical countries.

It is widely known that soil microbes play an important role in biogeochemical cycling, affecting plant growth, and creating soil structure. Faced with the widespread global changes, unravelling the response of soil microbes is essential for understanding soil feedbacks to climate changes. Therefore, there is an increasing interest in studying soil microbial diversity patterns from local to global spatial scales and in investigating changes in soil microbial community diversity and community structure under global changes. However, how soil microbial communities would be altered by natural environmental changes and/or by human induced environmental changes are still not well understood at the regional scale. The Tibetan plateau is known as ‘the third pole’ because of its high elevation of over 4000 m above sea level. Ecosystems in the Tibetan plateau, dominated by alpine grasslands, are fragile and vulnerable to global changes. The increase rate of air temperature is up to three times the global average level. However, we still lack knowledge on responses of soil microbial community to climate gradient and human-induced environmental changes, e.g. climate warming and grazing. This thesis investigated changes in bacterial and fungal community diversity, composition, and co-occurrence along a hydrothermal gradient in the Tibetan plateau grasslands, and the interactive effects of climate changes (warming) and human activities (grazing) on soil microbial functional communities. Specifically, this thesis includes four experiments: Experiment 1 studied the changes in soil bacterial community along an environmental gradient in the Tibetan plateau. The hypothesis was that alpha diversity of soil bacterial community would increase with higher precipitation and air temperature. We therefore selected sampling sites distributed in main grassland types in the Tibetan plateau. Microbial DNA extracted from soil samples were subjected to the next-generation sequencing to characterize soil bacterial diversity and community. Meanwhile, information of environmental factors 44 was also collected to clarify the driving forces of changes in soil bacterial communities. These factors included mean manual precipitation (MAP), mean manual temperature (MAT), soil moisture (SM), elevation, soil total organic carbon (SOC), total nitrogen (TN), soil carbon: nitrogen ratio (C/N), available phosphorus (AP), soil pH, plant richness, plant aboveground biomass (plant BiomassA), plant belowground biomass (plant BiomassB), NH4+-N, NO3--N, dissolved organic carbon (DOC), soil dissolved organic nitrogen (DON), soil microbial biomass carbon (MBC) and nitrogen (MBN). We used statistical methods including simple correlation, multivariable analysis and structural equation modelling (SEM) to elucidate spatial pattern and the relative importance of biotic and abiotic factors in structuring soil bacterial communities. In the SEM, climate factors were expected to affect soil microbial communities through their influences on plant and soil properties. Main findings included: in terms of overall bacterial diversity, the swamp meadow with better water conditions had significantly higher diversity than other habitat types, while the alpine desert had the lowest diversity. The overall alpha diversity was significantly correlated with factors that can indicate soil nutrient status including total soil organic carbon, total nitrogen, plant aboveground biomass, nitrate nitrogen (N) and other factors. The effect of environmental factors on the overall bacterial community structure variation was greater than that of spatial factors. The effects of mean annual precipitation (MAP) on soil bacterial alpha diversity were mostly indirect through affecting soil dissolved organic carbon (DOC) and plant richness based on the SEM. Among the environmental factors, the most influential factor for the differences of bacterial community structure was MAP. Unlike the effects on bacterial alpha diversity, MAP had a strong direct effect on soil bacterial community structure. Other factors such as soil DOC and soil pH affected soil bacterial community structure directly without through mediating intermediate variables. By contrast, mean annual 68 temperature (MAT) was not significantly related to soil bacterial diversity or community composition. Experiment 2 studied soil fungal community of the same soil samples as described in Experiment 1. We hypothesized that there would be a close association between soil fungal community diversity/composition and plant community diversity or composition. The main findings were: Ascomycetes were the most abundant phylum in all samples (84.56%), followed by Basidiomycetes and the Zygomycota. Significantly positive correlation between the relative abundance of Ascomycota and precipitation was found, while the relative abundance of Glomeromycota was not significantly correlated with precipitation. Based on the best-fitting regression model, the most important predictors of fungal species richness were pH and plant species richness. MAP also had substantial effects on soil fungal richness, mostly through its effects on soil pH and plant richness. Environmental factors and geographic distance can independently explain partial changes of fungal community structure with a higher effect by environmental factors. Compared to strong direct effects of soil pH, MAP affected soil fungal community composition by altering soil pH and plant community structure based on structural equation modeling (SEM). Experiment 3 studied the microbial co-occurrence network along the transect as described in Experiment 1 and 2 by integrating soil bacterial and fungal community data. In this study, Spearman correlation-based network was constructed, and a set of network topological properties were calculated. In addition, the impact factors of network properties were also investigated. The main findings were: The microbial network size of alpine meadows was greater than that of the alpine steppes. However, the modularity of alpine steppe was higher compared to alpine meadow. In addition, networks of alpine steppe had a larger average path length. Based on these differences in network topological features, soil microbial communities of alpine steppe were considered more stable under environmental interferences. 93 Fungal networks were found to have larger modularity, but smaller inter-nodes connectivity compared with bacterial networks. Although betweenness centrality of bacterial nodes was higher in the alpine meadows, degree centrality was higher in the alpine steppes. The regional meta-network (integrating bacterial and fungal taxa) structure was mostly related to MAP. However, the network topological features of alpine meadows and alpine steppe were driven by different factors. MAP and soil moisture were the significant impact factors for alpine steppe network but not for alpine meadow. The network of alpine meadows was strongly associated with plant factors including biomass and diversity. Besides, fungal networks were not associated with plant community factors, but related to climate factors and soil properties, suggesting that drivers of soil fungal network were different from that of fungal community diversity and structure. In Experiment 4, we investigated the effects of warming, grazing and their interaction in a factorial warming (+1.2-1.7 oC) and grazing (moderate intensity with ca. 50% vegetation consumption) experiment in a Tibetan alpine meadow on soil microbial communities by studying functional genes involved in soil carbon and nitrogen cycles. We hypothesize that warming would interact antagonistically with grazing to affect soil microbial functional communities. In this study, soil microbial communities were analysed by Geochip and environmental parameters including temperature, soil properties and plant communities were also collected. The main findings include: microbial functional gene structure and abundances were largely affected by the interactive effect of grazing and warming, rather than the main effect of warming or grazing. Compared to the control, grazing alone significantly increased the functional gene alpha diversity, changed the overall functional community structure, and increased the abundances of C fixation, C degradation, N mineralization and denitrification genes, likely due to the stimulating impact of urine and 118 dung deposition. Warming alone did not change these microbial properties, possibly related to the unchanged soil nutrient status. Despite an increase in soil NO3- concentrations and the deposition of urine and dung, the combined warming and grazing treatment did not change functional gene alpha diversity, community structure, or C/N cycling gene abundances. Our study revealed antagonistic interactions between warming and grazing on microbial functional gene structure and abundances, which remained stable under moderate intensity of grazing in a future warming scenario in the Tibetan alpine meadow. In sum, this thesis indicated that diversity, composition, and inter-taxa association of soil microbial communities are sensitive to environmental changes in the Tibetan plateau grassland. Climate changes and human activities affected soil microbial communities through direct and indirect pathways. More importantly, the evaluation of microbial-mediated processes in the Tibetan Plateau grasslands should take interactions between climate changes and anthropogenic activities into account.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
Full Text

In most parts of the world, drought is an inevitable and natural occurrence. However, as the climate continues to warm, and populations grow and expand, the negative impacts of this extreme weather event are predicted to become more pronounced. This leads many communities and stakeholders to question what is being done to prepare society for widespread drought? The following research determines different social and atmospheric characteristics that affect a city’s likelihood of having a drought policy in place.To do this, a thorough search was conducted at the city level to determine where drought policies are currently located in theU.S. The search included all U.S. cities with a population greater than 100,000. Policies and city plans were identified using a list of search terms ranging from “drought” and “water conservation” to “climate mitigation”. By identifying locations where these policies are currently in place this study explores commonalities between cities that have and have not implemented drought management plans.

Numerous small alpine glaciers occupy the high elevation regions of the central and southern Siena Nevada, California. These glaciers change size in response to variations in climate and are therefore important indicators of climate change. An inventory based on USGS topographic maps (l :24,000) revealed 1719 glaciers and perennial snow and ice features for a total area of 39.l5 ±7.52 km2. The number of 'true' glaciers, versus non-moving ice, is estimated to be 118, covering 15.87 ± 1.69 Km2. All glaciers were located on north to northeast aspects, at elevations >3000 m. Historical photographs, geologic evidence, and field mapping were used to determine the magnitude of area loss over the past century at 14 glaciers. These glaciers decreased in area by 31% to 78%, averaging 55%. The rate of area change was determined for multiple time periods for a subset of seven glaciers. Rapid retreat occurred over the first half of the twentieth century beginning in the 1920s in response to warm/dry conditions and continued through the mid-1970s. Recession ceased during the early 1980s, when some glaciers advanced. Since the 1980s each of the seven study glaciers resumed retreat. The uniform timing of changes in area amongst study glaciers suggests a response to regional climate, while the magnitude of change is influenced by local topographic effects. Glacier area changes correlate with changes in spring and summer air temperatures. Winter precipitation is statistically unrelated to changes in glacier area. Headwall cliffs above the glaciers alter the glacier responses by reducing incoming shortwave radiation and enhancing snow accumulation via avalanching.

This thesis examines whether short term (one to three weeks) microbial sensitivity to temperature and carbon (C) inputs can be predicted from peat characteristics driven by nutrient gradients. The aim was to determine if relationships exist between peat macronutrient (C, nitrogen (N), phosphorus (P)) concentrations, microbial community composition and the microbial response to changes in temperature and C supply. The focus of this thesis was on using peat macronutrient concentrations as explanatory variables as this is a metric which is easy to define and measure consistently, unlike other factors such as peat C quality and availability of nutrients. It was observed that, over short timescales, microbial respiration rates in peat soils increased in response to warming, nutrient (N and P) additions and increased labile C supply. In the first two experimental chapters it was found that peat respiration was sensitive to temperature, with increases of 10°C shown to increase microbial CO2 production by factors of 2.8 to 4.4. In the final two experimental chapters priming effects in peat were examined with C additions found to stimulate microbial activity and increases in peat derived CO2 flux, which could be attributed to priming. Despite the wide variation in nutrient concentrations in the peat soils examined no clear relationships between peat nutrient properties (total and available concentrations) and the magnitude of the microbial responses were observed.

Bioenergy is expected to play an increasingly significant role in the global energy budget. In addition to the use of liquid energy forms such as ethanol and biodiesel, electricity generation using processed energy crops as a partial or full coal alternative is expected to increase, requiring large-scale conversions of land for the cultivation of bioenergy feedstocks such as cane, grasses, or short rotation coppice. With land-use change identified as a major contributor to changes in the emission of biogenic volatile organic compounds (BVOCs), many of which are known contributors to the pollutants ozone (O3) and fine particulate matter (PM2.5), careful review of crop emission profiles and local atmospheric chemistry will be necessary to mitigate any unintended air-quality consequences. In this work, the atmospheric consequences of bioenergy crop replacement are examined using both the high-resolution regional chemical transport model WRF/Chem (Weather Research and Forecasting with Chemistry) and the global climate model CESM (Community Earth System Model). Regional sensitivities to several representative crop types are analyzed, and the impacts of each crop on air quality and climate are compared. Overall, the high emitting crops (eucalyptus and giant reed) were found to produce climate and human health costs totaling up to 40% of the value of CO2 emissions prevented, while the related costs of the lowest-emitting crop (switchgrass) were negligible.

Thesis (MSc)--University of Stellenbosch, 2004.
ENGLISH ABSTRACT: Most South African peach and nectarine production areas lack in adequate winter chilling. To address these issues, a conventional breeding programme was started, to develop new and improved stone fruit cultivars with special emphasis on climatic adaptation and pomological attributes. This study was conducted to test the accuracy of the scientific method called the phenological method of classification, currently used by the breeding programme to classify the selections in the second phase of evaluation according to chilling requirement. During April 2000 and May 2001 and continuing until the next spring, 20 oneyear- old shoots of 30 peach and nectarine selections were harvested fortnightly from an evaluation orchard on Bien Donné Experiment Farm, Simondium, Western Cape (34° S). All selections were previously categorised as high (>800 Utah chilling units [CU]), medium (400-800 CU) or _low «400 CU) chilling requirement based on phenologic observations. According to the preliminary classification of the selections included in this study, six selections were classified as high, three as medium and 21 as low chilling requirement. Two replicate bundles of shoots of each selection were prepared and forced at 25° C with continuous illumination until no further changes in bud burst occurred for a period of five days after which the shoots were then discarded. CU in the orchard were calculated according to the Utah and Infruitec models. The hours below 12° C and 7° C were also calculated. For each selection the number of days until 20% vegetative and reproductive bud break was plotted over day of year, Utah CU, Infruitec CU, hours below 12° C, and hours below 7° C, and expressed as a parabolic function. Similarly, the inverse of the number of days until 20% bud break or the rate of bud growth was also plotted against all the above variables. The area under these parabolas was statistically analysed using the CANDISC procedure of SAS Release 8.1. The groupings of the CANDISC procedure were more or less consistent with the preliminary groupings obtained with the phenoligical classification method. On 16 May 2000 and 15 May 2001, 100 one-year-old shoots of the same peach and nectarine selections were harvested from the evaluation orchard on Bien Donné Experiment Farm, covered in wet paper towelling and black plastic bags and placed in a cold room kept at a temperature range between 4° C and 7° C. Two replicate bundles of 10 shoots of each selection were prepared fortnightly and forced at 25° C with continuous illumination until no further changes in bud burst occurred for a period of five days after which the shoots were then discarded. CU accumulated in the cold room at each transferral date was calculated according to the Utah model. For each selection the number of days until 20% vegetative bud break was plotted over Utah CU, and expressed as a parabolic function. Similarly, the inverse of the number of days until 20% bud break or the rate of bud growth was also plotted against the above variables. The area under these parabolas was statistically analysed using the CANDISC procedure of SAS Release 8.1. Once again, the groupings of the CANDISC procedure were more or less consistent with the preliminary groupings obtained with the phenoligical classification method. Due to the nature of the scientific method used in this study, there is room for a certain margin of experimental error to occur, which could account for the misclassifications by the CANDISC procedure, when performed on the 2001 season's data. It can be concluded that the phenological method of classifying the selections, as currently used in the breeding programme, is consistent with the results of the scientific method described here. Therefore, it is recommended that the phenological method be used in future to classify the selections according to chilling requirement (CR), as this method is less time consuming and less costly to perform. Finally the outcome of the analysis of one season's data was used as calibration data against which the other season's data was tested and the consistency of the results, using one set of discriminant functions, was tested. It can be concluded that a unique set of discriminant functions is necessary for each winter season to accurately classify selections according to CR with the CANDISC procedure.
AFRIKAANSE OPSOMMING: 'n Studie van dormansie en koue behoefte van perskes en nektariens Gebrekkige winterkoue is 'n gegewe in die meeste Suid-Afrikaanse perske en nektarien-produksie-streke. Om die gevolge hiervan aan te spreek, is 'n konvensionele teelprogram tot stand gebring om verbeterde steenvrug cultivars te ontwikkel met voortreflike pomologiese eienskappe en wat aangepas is by die plaaslike klimaatstoestande. Hierdie studie is geloods om die akkuraatheid van die wetenskaplike metode, genoem die fenologiese klassifikasie metode, soos tans deur die teelprogram gebruik, waarvolgens seleksies volgens kouebehoefte geklassifiseer word, te toets. Vanaf April 2000 en Mei 2001 tot en met die daaropvolgende lente, is 20 eenjaar-oue lote van 30 perske en nektatrien seleksies twee weekliks in 'n fase 2 evaluasie boord op Bien Donné Proefplaas, te Simondium in die Wes- Kaap (34° S) versamel. AI die seleksies was vooraf op grond van fenologiese waarnemings geklassifiseer in kategorieë van hoog (>800 Utah koue-eenhede [CU]), medium (400-800 CU) of laag «400CU) ten op sigte van kouebehoefte. Hiervolgens val ses van die seleksies wat in die studie ingesluit is in die hoë-, drie in die medium- en 21 in die lae kategorie. Lote van elke seleksie is voorberei en in twee herhalings gebondel, waarna dit geforseer is teen 25° C met deurlopende beligting totdat geen verdere knopbreek vir 'n periode van vyf dae voorgekom het nie, waarna die lote verwyder is. CU in die boord is volgens die Utah en Infruitec modelle bereken. Die aantal uur onder 12° C en onder 7° C is ook bereken. Die aantal dae wat dit elke seleksie geneem het om 20% vegetatiewe en 20% reproduktiewe knopbreek te bereik is bereken en geplot teenoor die dag van die jaar, Utah CU, Infruitec CU, aantal uur onder 12° C en aantal uur onder 7° C en uitgedruk as 'n paraboliese funksie. Die inverse van die aantal dae tot 20% knopbreek, of die tempo van knopbreek, is op soortgelyke wyse geplot teenoor al bogenoemde veranderlikes. Die oppervlakte onder die parabole is statisties ontleed met behulp van die CANDISC prosedure van die SAS program (Vrystelling 8.1). Die groeperings wat met die CANDISC prosedure verkry is het grootliks ooreengestem met die groeperings volgens die fenologiese klassifikasie metode. Op 16 Mei 2000 en 15 Mei 2001, is 100 eenjaar-oue lote van dieselfde perske en nektarien seleksies in die evaluasie boord op Bien Donné versamel, toegedraai in klam handdoekpapier, in swart plastiek sakke geplaas en in 'n koelkamer geplaas waarvan die temperatuur konstant gehou is tussen die grense van 4° C en T" C. Twee herhalings van 10 lote elk, van elke seleksie, is twee weekliks voorberei en geforseer by 25° C met deurlopende beligting totdat geen verdere knopbreek vir 'n periode van vyf dae plaasgevind het nie, waarna die lote verwyder is. Op elke oordragdatum is die aantal CU, wat in die koelkamer geakkumuleer het, volgens die Utah model bereken. Die aantal dae wat dit elke seleksie geneem het om 20% vegetatiewe knopbreek te bereik is bereken en geplot teenoor die Utah CU en uitgedruk as 'n paraboliese funksie. Die inverse van die aantal dae tot 20% knopbreek , dus die tempo van groei, is op soortgelyke wyse bererken en geplot teenoor bogenoemde veranderlikes. Die oppervlak onder die paraboliese funksies is statisties ontleed met behulp van die CANDISC procedure. Die groeperings van die CANDISC prosedure het weereens grootliks ooreengestem met die groeperings wat met die fenologiese metode van klassifikasie verkry is. Weens die aard van die wetenskaplike metode wat tydens hierdie studie gebruik is, kom daar 'n sekere mate van eksperimentele fout voor, wat moontlik die misklassifikasies van die CANDISC prosedure kan verklaar, wanneer dit op die 2001 seisoen se data uitgevoer word. Die gevolgtrekking kan gemaak word dat die resultate van die fenologiese metode, soos dit tans deur die teelprogram gebruik word, ooreenstem met die resultate wat deur die wetenskaplike metode, wat hier beskryf word, verkry is. Dus word daar aanbeveel dat die fenologiese metode in die toekoms gebruik word om die seleksies te klassifiseer volgens koue behoefte (CR), aangesien hierdie metode minder tyd in beslag neem en goedkoper is om uit te voer. Laastens is die resultaat van die analise van een seisoen se data gebruik as kalibrasiedata waarteen die data van die ander seisoen getoets is om so ooreenstemmendheid van die resultate te toets as slegs een stel diskriminant funksies gebruik word. Die slotsom was dat 'n unieke stel diskriminantfunksies nodig is vir elke winter seisoen om die seleksies akkuraat met behulp van die CANDISC prosedure volgens koue-behoefte te klassifiseer.

Most of dengue transmission occurs in tropical and subtropical zones. As a result, studies on the dynamics of dengue transmission are principally focused in these areas. Less is known about the dynamics of dengue transmission and the interplay of social and climatic determinants in arid regions located at the fringe of transmission zones. This dissertation uses surveillance data from the state of Sonora, an arid region in northern Mexico, to examine three specific aims: 1) to assess relationships among social and climatic factors utilizing locality-level dengue incidence data across the state of Sonora, 2) to determine the correlation between the spatial pattern of dengue cases during an outbreak in Hermosillo, a large urban area, and neighborhood-level socio-economic and water supply factors using a novel case-control study design, and 3) to determine how dengue cases disseminated across two arid cities, Hermosillo and Navojoa, and to determine if changing socio-demographic patterns were similar between cities. Results from the first ecological study indicated that the distribution of dengue across the state was associated most strongly with the climatic gradient and, secondarily, by population size and lack of education. Underreporting in rural areas with lower access to transportation infrastructure was also detected. We demonstrated that a spatially-based case-control study design was useful in identifying associations between dengue transmission and neighborhood-level characteristics related to population density, lack of access to healthcare and water supply restrictions. Finally, the spatio-temporal study identified common patterns between the two cities/outbreaks. Dengue transmission arose and was maintained for 2-3 months in specific foci areas characterized by low access to healthcare and then the disease moved to contiguous areas. Recommendations for surveillance and control programs based on these results include: 1) in small localities at risk of transmission a combination of active and passive surveillance should be carried out for a period of time to determine if transmission is occurring, 2) monitoring water storage practices during water restrictions and ensuring appropriate messaging about covering storage containers should be made, and 3) spatial monitoring of dengue cases and agency reaction to initial disease occurrence could reduce spread to adjacent areas.

Models of phenology of the pine false webworm (PFW), Acantholyda erythrocephala and one of its parasitoids were developed from relationships between PFW spatial distribution and microweather. Development of subterranean stages of PFW was simulated from rate-summation models developed from nonlinear regression equations describing the relationship between temperature and rate of development of post-diapause prepupae and pupae. Defoliation caused by PFW increased the soil's exposure to solar radiation resulting in higher soil temperatures and a corresponding reduction in development time of subterranean stages. Predictability was enhanced slightly when the distribution of insects and temperature of the soil were incorporated into the model. Increasing the time increment used in the model from 1 to 4 h did not adversely affect its resolution. Mating and oviposition of PFW occur within a few hours of emerging from the soil and the majority of PFW eggs were mature and ready for deposition at female emergence. Potential fecundity of PFW was accurately predicted from adult wet and dry weights. The oviposition pattern of PFW was also described by a model based on temperature-dependent oviposition and ageing rate functions. The effect of larval web construction on the development of arboreal stages was investigated. When exposed to sunlight, the web traps heat and raises the body temperature of its inhabitants. A model was developed and used to examine the significance of the web microclimate for development of larvae. Relationships between web temperatures, canopy temperatures and standard meteorological methods were developed to permit using data from standard weather stations to drive the model. Larval development increased by 1.4 to 2.8 d when estimated web temperatures were incorporated into the model, while development was retarded by 2.6 to 4.0 d when canopy temperatures were used instead of meteorological screen temperatures. Two ichneumonid parasitoids, Sinophorus megalodontis and an undescribed species of Olesicampe were reared from eonymphs of PFW. Morphological methods for distinguishing the immature stages of the parasitoids were developed. A predictive model for subterranean development and adult longevity of Olesicampe sp. was used to describe and to compare phenological observations from emergence traps, Malaise traps and dissections of host larvae. The effectiveness of the parasitoids as natural control agents is discussed in relation to host synchrony, encapsulation, and multi- and superparasitism.
Land and Food Systems, Faculty of
Graduate

The rise in atmospheric CO2 partial pressures that is predicted for the 21st Century is likely to increase productivity and alter nutrient of C3 crop plants. Consequently, physiological data on plant growth and nutrition at elevated CO2 are required, because these data underpin simulation models, which are needed for management of crops under the CO2 scenario for the mid to late 21st Century.In particular, information is required about management of nitrogen(N) fertilisation because this mineral nutrient plays a central role in the growh of many crops. Rice was chosen as a model plant because of its widespread consumption throughout the world and its responsiveness to CO2 and N fertilisation. There were three major hypotheses: first, that early exposure of rice plants to high CO2 is required to achieve the maximum growth and tillering response; secondly, that early increases in growth and tillering at high CO2 are associated with the phytohormone, ethylene; and thirdly, that growth at elevated CO2 decreases leaf N concentrations required to support maximum dry mass production and photosynthetic rates (critical concentrations).Several tests and experiments were conducted and results noted. It is likely that grain yield will be greater as the atmospheric CO2 partial pressure rises even when N supplies are low, providing that high CO2 does not cause accelerated tiller abortion at low N.
Doctor of Philosophy (PhD)

In Canada, the control of relative humidity is a key issue in greenhouse production as it has a direct and significant effect on dehumidification cost, crop quality and yield. Experiments were carried out to measure plant transpiration rate and fruit yield under four different ambient water vapour pressure deficits. Four identical greenhouses were used to produce tomatoes (Lycopersicon esculentum Mill.) under four different regimes of water vapour pressure deficit (VPD). Dehumidification costs were highly correlated to VPD: low VPD produced low transpiration requiring little dehumidification. Thus, managing plant transpiration can lead to a more efficient use of transpiration for crop production. A model was developed to optimise greenhouse climatic conditions to maximize net profit. The present project validated this model, and compared measured values with those calculated from the transpiration and condensation sub-models and from the entire model itself. The sub-models and entire model proved to be accurate within 3% when used to simulate ideal climatic conditions for periods of one week or longer. Model sensitivity was greatest for exterior temperature because this factor affects heating costs without increasing yields. Using winter climatic conditions typical of Quebec City, Canada, three greenhouse climate control strategies were simulated and compared with respect to energy consumption and yield of a tomato crop. The merit and drawback of each strategy are discussed.

High rates of runoff and soil loss occur in temperate areas in late winter and early spring. A low-intensity rainfall simulator and a snowmelt simulator were developed to study soil erosion by snowmelt and/or spring rainfall on a sandy loam soil of southern Quebec. Erosive agent, land slope, thaw depth of partly frozen soil, and intensity and duration of the event were studied in the laboratory using the simulators. All these factors had significant effects on soil erosion. Sediment concentration, soil loss rate, and total soil loss increased with increasing land slope, thaw depth, and intensity, duration, and impact energy of the erosive agent. Duration showed a significant interaction with each of the other factors. interaction between thaw depth and intensity of the event was significant under both snowmelt and rainfall simulation, whereas interaction between land slope and intensity was significant under rainfall simulation, but not under snowmelt simulation. Erosive agent also interacted with each of the other factors. All these interactions increased soil loss. The presence of a frozen sublayer interacted with the other factors and greatly increased runoff, sediment concentration and total soil loss. Rainfall caused more soil loss than did snowmelt under the same conditions.

Thesis (M.A.)--Georgia State University, 2006.
Title from title screen. Susan Walcott, Paul Knapp, committee co-chairs; John Allensworth, committee member. Electronic text (106 p. : col. ill., col. maps) : digital, PDF file. Description based on contents viewed July 9, 2007. Includes bibliographical references (p. 103-106).

LIGHT
Com a entrada do novo modelo do setor elétrico, a previsão do consumo e de faturamento de energia elétrica passou a ter grande importância para as distribuidoras de energia elétrica, pois melhorando sua acertividade as empresas poderão elaborar seus programas de planejamento energético, manutenção e expansão de seu sistema de distribuição e principalmente evitar gastos com multas pelo não atendimento à totalidade de seu mercado consumidor. Para que esta previsão seja feita é necessário que se obtenham, os dados históricos do consumo de energia elétrica, da carga fornecida pela Distribuidora, porém como esses dados são séries multivariadas, isto é, são séries temporais que dependem de outras variáveis exógenas, levou-se em consideração também as séries climáticas (sensação térmica), as econômicas (índices financeiros) e o fator temporal (dias úteis, feriados, finais de semana.....). Este estudo, propõe um método alternativo para previsão de consumo e faturamento de energia elétrica, 15 passos a frente, através do desenvolvimento de um sistema inteligente, chamado SIPEE, baseado em redes neurais MLP multistep e foi desenvolvido para uma Distribuidora de Energia Elétrica que atende a boa parte do mercado consumidor do Estado do Rio de Janeiro, a Light Serviços de Eletricidade S.A..
When the new model of the electricity sector began to be used, the forecast of consumption and billing of electricity began to have great importance for the electricity distributors, improving their assertiveness as companies can develop their programs for energy planning, maintenance and expansion of its distribution system and particularly to avoid fines for not spending all of his service to the consumer market. For this prediction is made it is necessary to obtain historical data of energy consumption, the load supplied by the distributor, but as these data sets are multivariate, ie, they are time series which depend on other exogenous variables took into account also the series weather (wind chill), economic (financial ratios) and the factor of time (days, holidays, weekends .....). This study proposes an alternative method to forecast sales and consumption of electricity, 15 steps forward, by developing an intelligent system, called SIPEE, MLP neural networks based on multistep and was developed for an Electricity Distributor serving much of the consumer market in the State of Rio de Janeiro, Light Electrical Services SA.

I studied the onshore migrations of Atlantic cod (Gadus morhua) in the northern Gulf of St. Lawrence to test the predictability of the distributions and catches of a migratory predatory fish relative to physical oceanographic processes and the distributions and abundances of its prey. To survey daily fish distributions and abundances by species, hydroacoustic signal discriminant methods were developed which classified schools of cod, capelin (Mallotus villosus), and mackerel (Scomber scombrus) with 93% success. Physical oceanographic processes along the 150 km of coastline studied were characterized by Ekman-type upwellings and downwellings forced by alongshore winds at periods $>$3 d. Physical elements of this system (principally currents and temperature) were associated with cross-shore movements of cod and accounted for as much as 83% of the variance in mean trap catch. Cod and capelin formed coherent spatial distributions when capelin were congregated where sea temperatures were most favorable to cod (1 to 5$ sp circ$C) and mean capelin densities were above 100/10$ sp5$m$ sp3$. Coherences were in phase at larger scales ($>$10 km) but became increasingly out of phase at smaller scales. Cod distributions fit the predictions of an "ideal" distribution (allometric constant = 0.67) when two constraints were put on the relationship: (1) capelin densities above 100/10$ sp5$m$ sp3$, and (2) temperatures between 1 and 9$ sp circ$C.

A rice grain is composed of 90% starch, and amylose contributes to up 30% of the starch with the remainder as amylopectin. The structure of starch largely defines the quality of rice, yet the methods to characterise starch have not been reviewed recently. This thesis begins by using the simplest form of starch, debranched amylopectin, to detail and apply the principles of molecular weight theory using Size Exclusion Chromatography (SEC) to illustrate that without correct calibration the molecular weight distribution of starch has been underestimated. In contrast to amylopectin, amylose is difficult to isolate from flour without causing irrevocable damage, is unstable in an aqueous system and is believed to be impossible to debranch with isoamylase. Here an amylose-rich fraction was extracted directly from flour using hot water to avoid the structural–damaging isolation techniques used previously. The ability of isoamylase to debranch the amylose was shown through traditional methods of controlled enzyme degradation of the starch, ensuring that association of chains did not hinder access to the enzyme activation site, and through the contrast of 1H NMR spectra before and after the debranching event. Further, it was shown that 20% of carbohydrate was not recoverable from the SEC, and the unrecoverable carbohydrate is likely to be of high molecular weight and with long chains. High temperatures during the grain filling period are known to impede on the rice quality of one classification of non-waxy varieties. That hypothesis was rigorously examined by growing rice from a wide genetic background in three temperature regimes, followed by analysis of amylose at a functional, structural and synthesis level. From that phenotypic data, the rice varieties could be divided into three distinct groups – two of poorer quality in an increasingly warmer climate. Candidate single nucleotide polymorphisms (SNPs) have been identified, and a mechanism proposed, to explain the phenotypes. Linking a phenotype to a SNP allows the opportunity for wide scale screening of varieties to predict the quality of rice in an increasing warmer environment. Rice quality has the potential to change with elevated carbon dioxide levels, both alone and with increased temperature. Here, the quality traits of varieties grown in four combinations of temperature and carbon dioxide levels were assessed. The negative impact of temperature on grain quality was unable to be overcome by an increase in carbon dioxide in all but one quality. Chalk is the undesirable opaque belly of a grain that defines the market price of the grain. In elevated carbon dioxide, the proportion of grains containing a high amount of chalk per grain which will increase the market value of the grain and may help to alleviate the burden of climate change on rice farmers.

This thesis conducts a case study of how MARTA could address climate change adaptation through its transit asset management program. Two climate-modeling approaches are utilized to project potential future climate scenarios within MARTA's service area to identify significant climate stressors. These climate stressors are used to help identify vulnerable assets, operations, and locations in the MARTA system through several interviews conducted with key MARTA staff. The results of this basic climate vulnerability assessment are used to develop a series of short-term and long-term adaptation strategies that address these vulnerabilities. Next, a framework is proposed for addressing climate adaptation through MARTA's existing asset management program. Finally, the thesis proposes a general framework that other transit agencies could utilize to address climate adaptation through their asset management programs. The results of the climate vulnerability assessment indicate that the MARTA service area is likely to experience longer exposure to higher temperatures, flooding, wider variations in temperature, droughts, and more frequent high-wind events. Of these stressors, the MARTA system is most vulnerable to the effects of extreme and prolonged heat as well as flooding caused by intense precipitation events. Adaptation strategies to address these vulnerabilities include more frequent inspection of HVAC systems on buses and rail vehicles, increasing pumping capacity at underground rail stations, and incorporating low-impact developments into surrounded station areas. The limitations of the results of this case study and areas for further research from these limitations are also presented.