Global climate change is predicted to alter the weather patterns around the world, as climatic zones shift, forest carbon sequestration projects (e.g. the UK woodland carbon code) need to take into account the specific requirements of planted species. In the UK, oaks are an important charismatic group of trees favoured in recent planting programmes. The English oak (Quercus robur L.), has poor water conservation, but is a major component of natural forests in lowland UK. On the other hand, Holm oak (Quercus ilex L.) is a Mediterranean oak that has high water conservation and can also tolerate cold despite being restricted by minimum temperatures. At local scales, there may be advantages of planting either evergreen or deciduous oak species for forestry and climate mitigation. Alternatively, a comparative assessment of non native versus native productivity, may give clues to the invasiveness potential of Holm oak and its ability to out compete the deciduous oak along an urban to upland gradient. This thesis documents a series of field based experiments intended to analyse differences in carbon sequestration potential and photosynthetic efficiency between these two species and in relation to their environment within the Southwest UK. 520 one year saplings were planted, half in pots and half in nursery field beds situated on Dart- moor, the east Devon Dartmoor fringe, Totnes, and Plymouth city centre. Originally two sites were chosen for their relative ‘urban’ qualities, two at ‘rural’ localities, one upland and a control site with access to a polytunnel for comparisons with well-watered and non nutrient limited trees. However, data analyses showed that sapling characteristics were site specific with the five sites falling along an urban, rural to upland gradient. The field experiments included monthly height and diameters (ground level diameter or DAG), monthly assimilation rates and analy- sis of chlorophyll fluorescence to aid interpretation of photosystem II functioning and sapling ‘vitality’. Further laboratory experiments analysed specific leaf area (SLA), mass based leaf Nitrogen (Nleaf ) and carbon (Cleaf), with differences between sun and shade leaves included, to aid comparisons between species and sites. The final experiment was a destructive harvest and this was used to find total biomass estimates and carbon allocation to different root shoot fractions. In order to quantify differences between saplings and adult trees a smaller experiment was con- ducted in the canopy using experienced climbers and leaf level productivity analysed. Intrinsic water use (iWUE), stomatal conductance (Gs), means net assimilation rates (An) and chloro- phyll fluorescence parameters; Variable fluorescence over maximum fluorescence (Fv/Fm) and performance index (PI) were measured and relative carbon assimilation rates and productivity assessed and compared between species at one urban , rural and upland site. Results showed that Q. ilex allocated relatively more carbon to branches and leaves as a sapling which in turn increased growth rate and whole tree assimilation rates to larger values than the deciduous oak despite Q. robur being able to increase maximum assimilation rates in response to increasing temperatures. This gives Q. ilex the advantage and overall biomass was higher at all sites than Q. robur apart from the upland site where there were no differences in biomass accumulation between species. However, despite no significant difference in biomass at this site Q. robur had greater survival and photosystem II functioning. In mature trees Q. ilex was under stress and Nleaf and carbon sequestration potential were higher in the deciduous species at the urban site. In contrast, Q. robur was under stress at the upland site at Castle Drogo where thin and nutrient poor soils have made it more vulnerable to drought stress. Here, mature Q. ilex showed reduced photosynthetic efficiency in relation to cold and drought, but was able to recover when milder temperatures occurred. The results were site specific, with a reduction in both SLA and relative allocation to the leaf weight fraction (LWF) in Q.robur the only common urban related effect seen. The potential for Q. ilex to perform well at sapling stage is due to its morphological plasticity and drought tolerance. This species may become more prevalent within the Southwest as local climates continue to push it northwards from its natural Mediterranean range. In contrast, if Q. robur continues to suffer from defoliation and fungal attack and this may leave it more vulnerable to competition throughout less fertile and drier areas of its natural range.

Quantifying above-ground biomass (AGB) and carbon sequestration has been a significant focus of attention within the UNFCCC and Kyoto Protocol for improvement of national carbon accounting systems (IPCC, 2007; UNFCCC, 2011). A multitude of research has been carried out in relatively flat and homogeneous forests (Ranson & Sun, 1994; Beaudoin et al.,1994; Kurvonen et al., 1999; Austin et al., 2003; Dimitris et al., 2005), yet forests in the highlands, which generally form heterogeneous forest cover and sparse woodlands with mountainous terrain have been largely neglected in AGB studies (Cloude et al., 2001; 2008; Lumsdon et al., 2005; 2008; Erxue et al., 2009, Tan et al., 2010; 2011a; 2011b; 2011c; 2011d). Since mountain forests constitute approximately 28% of the total global forest area (Price and Butt, 2000), a better understanding of the slope effects is of primary importance in AGB estimation. The main objective of this research is to estimate AGB in the aforementioned forest in Glen Affric, Scotland using both SAR and LiDAR data. Two types of Synthetic Aperture Radar (SAR) data were used in this research: TerraSAR-X, operating at X-band and ALOS PALSAR, operating at L-band, both are fully polarimetric. The former data was acquired on 13 April 2010 and of the latter, two scenes were acquired on 17 April 2007 and 08 June 2009. Airborne LiDAR data were acquired on 09 June 2007. Two field measurement campaigns were carried out, one of which was done from winter 2006 to spring 2007 where physical parameters of trees in 170 circular plots were measured by the Forestry Commission team. Another intensive fieldwork was organised by myself with the help of my fellow colleagues and it comprised of tree measurement in two transects of 200m x 50m at a relatively flat and dense plantation forest and 400m x 50m at hilly and sparse semi-natural forest. AGB is estimated for both the transects to investigate the effectiveness of the proposed method at plot-level. This thesis evaluates the capability of polarimetric Synthetic Aperture Radar data for AGB estimation by investigating the relationship between the SAR backscattering coefficient and AGB and also the relationship between the decomposed scattering mechanisms and AGB. Due to the terrain and heterogeneous nature of the forests, the result from the backscatter-AGB analysis show that these forests present a challenge for simple AGB estimation. As an alternative, polarimetric techniques were applied to the problem by decomposing the backscattering information into scattering mechanisms based on the approach by Yamaguchi (2005; 2006), which are then regressed to the field measured AGB. Of the two data sets, ALOS PALSAR demonstrates a better estimation capacity for AGB estimation than TerraSAR-X. The AGB estimated results from SAR data are compared with AGB derived from LiDAR data. Since tree height is often correlated with AGB (Onge et al., 2008; Gang et al., 2010), the effectiveness of the tree height retrieval from LiDAR is evaluated as an indicator of AGB. Tree delineation was performed before AGB of individual trees were calculated allometrically. Results were validated by comparison to the fieldwork data. The amount of overestimation varies across the different canopy conditions. These results give some indication of when to use LiDAR or SAR to retrieve forest AGB. LiDAR is able to estimate AGB with good accuracy and the R2 value obtained is 0.97 with RMSE of 14.81 ton/ha. The R2 and RMSE obtained for TerraSAR-X are 0.41 and 28.5 ton/ha, respectively while for ALOS PALSAR data are 0.70 and 23.6 ton/ha, respectively. While airborne LiDAR data with very accurate height measurement and consequent three-dimensional (3D) stand profiles which allows investigation into the relationship between height, number density and AGB, it's limited to small coverage area, or large areas but at large cost. ALOS PALSAR, on the other hand, can cover big coverage area but it provide a lower resolution, hence, lower estimation accuracy.

Lake Victoria (LV), is the largest tropical fresh water lake. It is however facing a myriad of challenges like eutrophication, introducing species, mass extinction and climate change. Eutrophication has mostly been seen as a result of non-point pollution from upstream agricultural areas. However, studies have found that atmospheric deposition could perhaps be the greatest cause of nutrient loading in the lake. Our study looked at black carbon as one of the factors favoring eutrophication in LV. Black carbon is a product of incomplete combustion of biomass or fossil fuel. Biomass burning is prevalent in many areas of Africa and our results have shown a great spatial and temporal variability in its concentration in sediments. The sedimentation rates calculated after analyzing 210Pb activity were 0.87, 0.53 and 0.35 g cm-2 yr-1 while the average black carbon concentrations were 4.6, 2.1 and 6.9 mg g-1 for Siaya, Kisumu and Busia, respectively. These results provided valuable information when compared to past historical events in the Lake region especially eutrophication. The study also found that soot BC has been increasing in the past 100 years suggesting the input from fossil fuels. This study elucidates the complexity of drivers of eutrophication in Lake Victoria. Nitrogen and Phosphorous from the upstream agricultural sites has long been seen as the main cause of eutrophication. Through this study we find that soot deposition in the lake coincides with the period of increased primary productivity. The Total Organic Carbon and Total Nitrogen were also analyzed and have shown increased remarkable increase with time. All these geochemical variables are a testament to the increased role of human activities on the lake’s productivity. While other studies on soot in marine environments have associated bacterial growth to nutrients attached to soot black carbon. We correlate the concentration of soot in Lake Victoria basin to blooming of cyanobacteria.

Three north central Texas reservoirs (Grapevine Reservoir, Lake Ray Hubbard, Lewisville Reservoir) were investigated in order to characterize the nutritional ecology, phytoplankton community structure, and primary productivity within the trophogenic zones of each. Emphasis was placed on elucidating the relative influences of the major nutrients (C, N, P, Fe, Si) and various other physico-chemical parameters on phytoplankton community biomass, structure, and productivity. Extensive physical, chemical, and biological analyses consisting of approximately eighty parameter measurements were made on each of twenty-three integrated water samples (surface to three meters) taken from the three reservoirs during the period July, 1971 to June, 1972. New methods which were employed included a high-intensity ultraviolet photocombustion procedure for the determination of total nitrogen, phosphorus, and iron, and an in vitro oxygen method for estimating community metabolism. General chemical and physical regimes are described for the three reservoirs, and various interrelationships discussed. Phytoplankton communities are delineated on bases of species composition, volume, diversity, pigments, and metabolism data. The more salient biotic and physico-chemical interrelationships are examined within the context of the limiting nutrient controversy.

Master of Science / Department of Agricultural Economics / Jeff Williams / This study examines the net returns from grain and biomass production from seven annual crop rotations using six different management scenarios. This study also examines the profitability of producing biomass from three perennial crops using four management scenarios. Soybeans were rotated with grain sorghum, dual purpose sorghum, photoperiod sensitive sorghum, brown mid-rib (BMR) sorghum, and corn. Continuously cropped corn was also included. Perennial grasses including switchgrass and big bluestem were compared to a traditional crop, alfalfa. Yields and input data for the crops was from an experimental field study conducted at Kansas State University, Manhattan KS. Enterprise budgets were constructed for rotations of five sorghum varieties with soybeans, corn and soybeans, and continuous corn. Enterprise budgets were also constructed for three perennial crops; consisting of switchgrass, big bluestem grass, and alfalfa. Perennial crop costs and returns are estimated over an assumed 10 year production horizon. Costs and net returns for each of these budgets were compared to determine which crop rotation was the most economically feasible. Yield and input rates, excluding soybean yield and inputs, used were collected from an agronomic field experiment at Manhattan located in Riley County, Kansas (Propheter, 2009; Roozeboom et al., 2011). Costs of inputs were from USDA Agricultural Prices, Kansas State University farm management guides, and Sharpe Brothers Seed Company. Harvest costs are from Kansas State University farm management guides and a Northeastern Colorado and Northwestern Kansas producer survey. The corn- soybean rotation had the highest net returns per acre across all annual crop scenarios. The corn-soybean rotation did not have the highest net returns per acre when an alternative price was used for the photoperiod sensitive sorghum-soybean rotation. The dual purpose sorghum-soybean rotation had the second highest net returns per acre across all annual crop scenarios. The corn-soybean and dual purpose sorghum-soybean rotations had high grain net returns, and low to average biomass production costs. Alfalfa had the highest amortized net returns of the perennial crops, and had positive establishment year net returns. Alfalfa had higher amortized net returns and establishment year net returns than switchgrass and big bluestem.

Conversion of biomass to energy does not contribute to the net increase of carbon dioxide in the environment, therefore the use of biomass waste as a clean and renewable fuel source is an attractive alternative to the use of fossil fuels. Biomass can be converted to energy via direct combustion or via thermo-chemical conversion to liquid or gas fuels. This study focuses on employing gasification technology to convert biomass waste to producer gas, which is then cleaned and fed as gaseous fuel into the gas turbine. Since the producer gases are usually low caloric values, the power plants performance under various operating conditions has not yet been proven. In this study, system performance calculations are conducted for a 5MWe and a 20MWe power plants using commercial software ThermoFlow. The power plants considered including simple gas turbine systems, steam turbine systems, combined cycle systems, and steam injection gas turbine systems (STIG) using the producer gas with low caloric values at approximately 30% and 15% of the natural gas heating value. The low caloric value fuels are shown to impose high back compressor pressure and increased power output due to increased fuel flow. Power augmentations under four different weather conditions are also calculated by employing gas turbine inlet fog cooling. Different capacity options for the heat recovery steam generator (HRSG) that provides the steam for STIG are analyzed.

Orientador: Fábio Minoru Yamaji / Resumo: Os atuais padrões mundiais de consumo energético estão baseados na utilização de combustíveis fósseis, os quais, além de serem não renováveis, geram diversos problemas ambientais. Nos últimos anos houve um aumento na busca por fontes energéticas alternativas e mais sustentáveis, como as biomassas provenientes de resíduos agroindustriais, as quais podem apresentar grande potencial energético por área e baixos impactos ambientais. Com o intuito de minimizar os problemas ambientais relacionados à geração e descarte de resíduos provenientes das atividades de cultivo de cogumelos, esse estudo teve como objetivo avaliar o potencial bioenergético do resíduo de cultivo de shiitake (RCS) seco e por meio de sua conversão termoquímica pelo processo de pirólise em três temperaturas diferentes (350°C, 450°C e 550°C). Mediante às análises, o biocarvão de 350°C (BC350) foi considerado com o maior potencial energético devido à menor quantidade de cinzas e maiores quantidades de materiais voláteis, carbono fixo, poder calorífico, rendimento gravimétrico e fator de rendimento gravimétrico. As análises químicas e físicas revelaram que o RCS seco apresenta uma natureza bastante complexa, característica comumente encontrada em materiais de origem lignocelulósica. As análises termogravimétricas foram realizadas em três rampas de aquecimento, 10°C/min, 15°C/min e 20°C/min, em atmosfera oxidante e inerte. Foram identificadas etapas de conversão referentes à perda de água e degradação de hemicelulo... (Resumo completo, clicar acesso eletrônico abaixo) / Current global patterns of energy consumption are based on the use of fossil fuels, which are not only non-renewable resources, but also generate vast environmental problems. Recent years have witnessed an increasing search for alternative, more sustainable, energy sources, such as biomasses originated from agroindustrial residues, a material that may present great energetic potential per area and minor environmental impacts. Aiming at minimizing environmental impacts related with the generation and discard of mushroom cultivation residues, the present study intended to evaluate the bioenergetic potential of the spent shiitake substrate (SSS), both in its dry form and after its thermochemical conversion by a pyrolysis process in 3 different temperatures (350°C, 450°C e 550°C). Further analyses founded the consideration that the 350°C biochar (BC350) was that with the greatest energetic potential, due to its reduced ash amounts and higher volatile amounts, fixed carbon, heat value, gravimetric yield and gravimetric yield factor. Chemical and physical analyses revealed that the dry SSS possesses a highly complex nature, characteristics commonly found in lignocellulosic materials. Thermogravimetric analyses were performed in 3 heating rates, 10°C/min, 15°C/min and 20°C/min in oxidizing and inert atmospheres. Conversion steps related with water loss and degradation of hemicellulose, cellulose and lignin have been identified. The kinetic study was carried out by non-isothermal and non-isoconversional Kissinger method. The activation energies obtained were of 110.3 kJ mol-1 and 136 kJ mol-1 for the SSS and BC350, respectively and are within the range found for other biomasses. The SSS presented features that allow the conclusion that such residue possesses great potential for bioenergy generation applications, potential which may be improved by means ... (Complete abstract click electronic acess below) / Mestre

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. 2014. / Sugar cane bagasse and switch grass were used to investigate their potential in the remediation (decreasing metal ion concentration and increasing pH) of Acid Mine Drainage (AMD) and the possibility that the AMD residue sludge containing cellulose could be further hydrolysed using a commercial cellulase enzyme system to produce glucose for bioprocesses. In general both the feedstocks series appeared to increase pH and reduce dissolved iron concentration after being incubated with AMD for a period of 14 weeks at room temperature. The milled switch grass was shown to have a greater remediating effect on AMD, raising the pH from 2.11 to 5.46, and decreasing iron concentration from 500mg/l to 174mg/l, a decrease of 62%. The sugar cane bagasse was shown to have the least remedial effect, increasing pH from 2.11 to 2.38, and only reducing iron concentration by 30%. The 2‐5cm switch grass raised the pH from 2.11 to 3.86, and the iron concentration was reduced from 500mg/l to 283mg/l, a 42% reduction. The milled grass series was chosen for further enzymatic hydrolysis. The milling reduced the size of the switch grass and destroyed the cell structure making it more accessible to AMD treatment. This also allowed the enzyme in the hydrolysis to penetrate to the fibres and reach the sugar oligomers. The sludge of the AMD treated switch grass was incubated with cellulases enzymes for 24 hours at 50oC, producing glucose concentration of up to 4,86mg/ml.

South Africa is economically vulnerable to climate change because its economy is powered by electricity generated from coal fired power stations. There is a need to reduce the reliance on fossil fuel energy not only because of greenhouse gas emissions but also energy security. Bamboo is touted as a renewable energy source, however, like other woody biomass material, it has poor physicochemical properties and low energy densities. Therefore, the bamboo samples utilized in this study were subjected to thermal pre-treatment methods to improve on their combustion and physicochemical properties. Bamboo samples of 1, 3 and 4+ years old were subjected to torrefaction at 250°C and 280°C as well as low temperature carbonisation at 350°C and 400°C. A standard HGI method was modified during the course of this research for studying the grindability of the raw and treated bamboo material. The fuel properties and combustibility of these raw and thermally treated bamboo materials were then studied using thermogravimetric analysis. The raw bamboo samples exhibited a CV ranging from 17 MJ/kg to 18 MJ/kg, whereas the torrefied samples and the carbonised samples had a CV ranging from 25 MJ/kg to 28 MJ/kg and 28 MJ/kg to 30 MJ/kg, respectively. The 4 year old bamboo carbonised at 400°C had the highest CV of 30.24 MJ/kg. The CV improvement occurred as a result of molecular modification observed through an increase in fixed carbon content from 16 to 74%. The energy yields ranging from 48 to 74% were achieved for the torrefied samples and 44 to 54% for the low temperature carbonised samples, depending on the age of the bamboo sample. At torrefaction temperatures tested, the 4 year old bamboo had the highest mass and energy yield, whereas at carbonisation temperatures, 3 year old bamboo had the highest. The number of differential thermogravimetric peaks was observed to decrease from 2 to 1 as the thermal treatment temperature increased to a carbonisation range (350-400) °C. This can be attributed to the less VM content in the carbonised samples. The raw bamboo and thermally treated bamboo had higher reactivity, lower ignition and burnout temperatures compared to that for coal. Blending of coal with bamboo (raw and thermally treated) appeared to increase the reactivity and lower the ignition temperature during co-firing. The activation energies of the individual fuels ranged from 56 to 289 kJ/mol, using the Ozawa model. Bamboo samples carbonised at 400°C had the highest activation energy, irrespective of age. The activation energy was also the highest when co-firing a blend with the highest proportion of coal. Based on the co-firing tests undertaken in the TG analyser in which a percentage of coal is blended with various proportions of raw and thermally treated bamboo, the results showed that as the percentage of coal in the blend increases there is less interaction or influence of biomass. The role of biomass is to aid with ignition of devolatilization in the coal at lower temperatures. At the carbonisation stage, biomass behave more like coal in principle. It was confirmed in this study that in terms of combustibility, the torrefied bamboo samples had a greater capacity to provide lower ignition and burnout temperatures over the low carbonised bamboo samples utilized, and this might support its application as a source of fuel in an industrial burning combustor. The carbonised 4 year old bamboo appears to be the preferred alternative source fuel to be fired solely in an existing pulverised boiler in South Africa or co-fired with coal due to the carbonised bamboo samples exhibiting the higher CV and more coal-like combustion profile.

The thesis presents a thorough, in-depth study that fills some of the gaps in the knowledge of the impacts of woodland utilisation in communal areas. The chosen case study villages are in Bushbuckridge, a government gazetted Integrated Sustainable Rural Development programme node, making the results pertinent to sustainable energy policy reform in South Africa. A case-study of two villages was used to investigate the spatial and structural changes in fuelwood supply in response to fuelwood extraction as well as the changes in use-patterns over time. A survey of the structure and composition of the woody vegetation and wood harvesting patterns around the villages was conducted and compared against historical data, spanning 17 years. Total wood stock in the communal woodlands of both villages declined over the study period; the loss being greater in Welverdiend. Significant, negative change in the structure and species composition, particularly of species that are commonly harvested for fuelwood has occurred in Welverdiend but not in Athol. The absence of negative impacts in Athol implies that harvesting regimes here are more sustainable but it is more likely that this is due to the lower human population and lower fuelwood extraction pressure. The changes in woodland structure were linked to landcover change patterns that occurred in the villages over the last 44 years, from their creation through forced resettlements on old farms in the area. Landcover change patterns were similar in both villages since 1965 but there was significantly greater woodland loss in Welverdiend (48% woodland loss) in comparison to Athol (25% woodland loss). The systematic loss of woodland areas to agricultural fields was linked to expanding residential areas due to human population growth. Deforestation occurred where woodlands were already impacted through selective harvesting. The physical changes in woodland structure and landcover were linked to a detailed socio-economic analysis of the two villages, providing critically important data for the sustainable management of woodlands in South Africa. The impact of access to electricity on fuelwood consumption rates was carried out through analysis of the economic, time and opportunity costs of fuelwood collection, compared against the different fuelwood availability in each village. In Welverdiend demand for fuelwood has so far proved inelastic; households have adjusted their fuelwood collection regimes, going on fewer collection trips but spending longer times for each trip but ultimately household investment is similar to that in Athol. Fuelwood demand is maintained in Welverdiend by the availability of purchased fuelwood and harvesting in new sites. A model to predict the socio-economic factors at the household and per capita level which affect fuelwood consumption was developed. Revealing in the process that households with access to electricity used less fuelwood annually and the amounts of fuelwood used were influenced by the household perceptions of fuelwood scarcity in the village, Household population size had a direct bearing on the likelihood of households switching to electricity with every addition to the household size decreasing the likelihood of switching by 48%. This study has major implications for the government’s on-going rural electrification programme. Interventions are required that raise awareness about fuelwood availability trends, based on landscape developments and targeting women as the main users of fuelwood.