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Mozambique has vast forestry resources and also considerable biomass waste material such as bagasse, rice husks, sawdust, coconut husks and shells, cashew nut shell and lump charcoal waste. The potential of the total residues from the agricultural sector and the forest industry is estimated to be approximately 13 PJ. This amount of energy covers totally the production of charcoal which amounted to approximately 12.7 PJ in 2006. Although biomass is an attractive renewable source of energy, it is generally difficult to handle, transport, storage and use due to its lower homogeneity, its lower energy density and the presence of non-combustible inorganic constituents, which leads to different problems in energy conversion units such as deposition, sintering, agglomeration, fouling and corrosion. Therefore, a pretreatment of the biomass to solve these problems could lead to a change of current biomass utilization situation. The aim of this study is to convert Mozambican woody biomass residue into a solid biochar that resembles low-grade coal. In this work the current energy situation in Mozambique has been reviewed, and the available and potential renewable sources including residues from agricultural crops and forest industry as energy have been assessed. It was found that the country is endowed with great potential for biofuel, solar, hydro and wind energy production. However, the production today is still far from fulfilling the energy needs of the country, and the majority of people are still not benefiting from these resources. Charcoal and firewood are still the main sources of energy and will continue to play a very important role in the near future. Additionally, enormous amounts of energy resources are wasted, especially in the agricultural sector. These residues are not visible on national energy statistics. The chemical composition and the fuelwood value index (FVI) showed that by failing to efficiently utilise residues from Afzelia quanzensis, Millettia stuhlmannii and Pterocarpus angolensis, an opportunity to reduce some of the energy related problems is missed. An evaluation of effect of a mild wet torrefaction pretreatment showed that the chemical composition of the biochar is substantially different than the feedstock. The use of diluted acid as catalysts improves the biochar quality, namely in terms of the energy density and ash characteristics; however, the increment of the S content in the final product should be considered for market acceptance (because the fuels have a maximum allowance for S concentration). The thermal behaviour of the untreated and treated biomass was also investigated. The pyrolytic products of umbila and spruce were affected by the treatment and catalyst in terms of yield and composition of the vapours. / <p>QC 20150202</p>

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.