The study focused on four research objectives: 1. To identify the species and provenances of eucalypts most suitable for biomass production in Great Britain. 2. To compare growth of eucalypts with other promising short rotation forestry genera. 3. To develop volume and biomass functions for E. gunnii. 4. To estimate yields and patterns of growth for E. gunnii. Searches on CAB abstracts and World of Science showed that there was limited research conducted on eucalypts in the UK. This research provides an original contribution to knowledge through; a long term assessment of the performance of species of cold tolerant eucalypts across a range of sites, identification of the basis for the rapid growth of eucalypts in comparison with trees from other genera, identification of the best fit function to describe stem form in E.gunnii and a characterisation of the pattern of growth in this species. The thesis provides an account of the long history of eucalypts in the UK, the first record of a eucalypt being planted in Britain probably being Eucalyptus obliqua in the late 1700s (Aiton 1789). A review is then provided of the experience and constraints to growing nine eucalypt species in the UK and their potential for short rotation forestry are described. The rapid growth of eucalypts makes them well suited to short rotation forestry, but there are considerable risks from frosts and extreme winters. Results from a trial established in Cumbria, north west England are described. Survival and growth was compared between E.gunnii, E. nitens and native or naturalised species, identified by Hardcastle (2006) as having potential for short rotation forestry. The rapid rate of growth of E. gunnii was attributed to a combination of large leaf area, a long period of growth during the year and a high specific leaf area. There was 99% mortality of E. nitens at the trial over winter, preventing comparison with other species. At the same trial and assessment was made of frost damage during the winter of 2009-2010, which proved to be the coldest for thirty years (Met Office 2010). E. gunnii was found to be more cold-tolerant than E. nitens, with 35% of the former surviving the winter and less than 1% of the latter. Larger trees were damaged more so than smaller trees reinforcing the argument for good silviculture to promote rapid, early growth. The study on stem form and growth of E. gunnii represents the first in the UK. Volume, height and dbh of a total of 636 trees, measured by felling, optical dendrometer and terrestrial laser scanner were used to test the goodness of fit of a volume function developed in France by AFOCEL and is South America by Shell Oil. The AFOCEL function was found to predict volume with less bias and be suitable for all but the smallest trees. Characterisation of growth curves using mined historic data indicated yields of 16 m3 ha-1 y-1 or approximately 8 t ha-1 y-1 at 20 years old. In contrast, growth curves derived from stem analysis of nine trees from Chiddingfold (south east England) and Glenbranter (central western Scotland) indicated lower yields at 7 m3 ha-1 y-1 at age 28 years and 4.5 m3 ha-1 y-1 at age 30 years respectively. Evidence from plantings elsewhere in the UK show that higher rates of growth are possible, but also that yields are often compromised by high mortality.

Short Rotation Forestry (SRF) for bioenergy could be used to meet biomass requirements and contribute to achieving renewable energy targets. As an important source of biomass it is important to gain an understanding of the implications of large-scale application of SRF on the soil-atmosphere greenhouse gas (GHG) exchange. This study examined the effects of land use change (LUC) from grassland to SRF on soil fluxes of methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2), and the important drivers in action. Examining soils from a range of sites across the UK, CO2 emission potentials were reduced under SRF with differences between coniferous and broadleaved transitions; these changes were found to be related to changes in soil pH and microbial biomass. However, there were limited effects of SRF tree species type on CH4 and N2O fluxes. A detailed study at an experimental SRF site over 16 months demonstrated a reduction in CH4 and net CO2 emissions from soils under SRF and revealed intriguing temporal dynamics of N2O under Sitka spruce and common alder. A significant proportion of the variation in soil N2O fluxes was attributed to differences between tree species, water table depth, spatial effects, and their interactions. The effects of microtopography (ridges, troughs, flats), and its interactions with water table depth on soil GHG fluxes under different tree species was tested using mesocosm cores collected in the field. Microtopography did not significantly affect soil GHG fluxes but trends suggested that considering this spatial factor in sampling regimes could be important. N2O fluxes from Sitka spruce soils did not respond to water table depth manipulation in the laboratory suggesting that they may also be determined by tree-driven nitrogen (N) availability, with other research showing N deposition to be higher in coniferous plantations. An N addition experiment lead to increased N2O emissions with greatest relative response in the Sitka spruce soils. Overall, LUC from rough grassland to SRF resulted in a reduction in soil CH4 emissions, increased N2O emissions and a reduction or no change in net CO2 emissions. These changes in emissions were influenced both directly and indirectly by tree species type with Sitka spruce having the greatest effect on N2O in particular, thus highlighting the importance of considering soil N2O emissions in any life cycle analysis or GHG budgets of LUC to SRF for bioenergy. This research can help inform decisions around SRF tree species selection in future large-scale bioenergy planting.

The purpose of this thesis is the determination of a minimum market price for Short-Rotation Forestry (SRF) willow biomass grown in monoculture and windbreaks in Quebec and Ontario. Full cost budgeting was used and developed on a Microsoft Excel spreadsheet. Harvest cycles of 3 and 4 years for monoculture plantations, and 8 years for windbreaks were investigated. Estimates for establishment and other preharvest costs were obtained from mid-sized (5 hectares) commercial SRF willow plots in Quebec and Ontario. / For the monoculture plantations, irrespective of cycle length, and using the base case figures, the final delivery cost of willow biomass ranged between 74-126 $/odMg and 63--109 $/odMg based on current and projected costs respectively. These hold for yields between 7 and 11 odMg/ha/yr. Moreover, the 4-year cycle was revealed to be more economically efficient than a 3-year cycle. Along with yield, the main cost factors affecting the economics of SRF monoculture plantations are: harvesting, transportation to a processing plant, land lease management. For the two major energy markets, ethanol and electricity production (biomass in replacement of coal), SRF willow biomass in monoculture plantations does not appear to be a viable feedstock given present technology and yields. In the short run, a more promising outlet for willow biomass is space heat production for small buildings, farm complexes, etc. In this market, many potential buyers can afford to pay a higher price for biomass than ethanol or electricity utilities. / In the windbreak system, biomass could be produced for between 44 and 68 $/odMg, assuming that yields between 12 to 20 odMg/ha/yr can be achieved. At this price, windbreak biomass is not a competitive feedstock for ethanol or electricity generation, but is attractive for space heat production. (Abstract shortened by UMI.)

No description available.

Despite the negative effects of fossil fuels on the environment, these remain as the primary contributors to the energy sector. In order to mitigate global warming risks, many countries aim at reducing greenhouse gas emissions. Bioenergy crops are being used as a substitute for fossil fuels and short rotation forestry is a prime example. In order to examine the sustainability of energy crops for fuel, typical European short rotation forestry (SRF) biomass, willow (Salix spp.) and poplar (Populus spp.) are examined and compared to rapeseed (Brassica napus L.) in respect to various aspects of soil respiration and combustion heat obtained from the extracted products per hectare. Various approaches are used to look at an As-contaminated site not only in the field but also in a soil-column experiment that examines the fate of trace elements in SRF soils, and in an analysis using MICMAC to describe the driving factors for SRF crop production. Based on the cause-effect chain, the impacts of land-use change and occupation on ecosystem quality are assessed when land-use is changed from degraded land (grassland) to willow and poplar SRF. A manual opaque dynamic closed chamber system (SEMACH-FG) was utilized to measure CO2 emissions at a willow/poplar short rotation forest in Krummenhennersdorf, Germany during the years 2013 and 2014, and at a rapeseed site in 2014. Short rotation forest soils showed higher CO2 emission rates during the growing season than the dormant season – with a CO2 release of 5.62±1.81 m-2 s-1 for willows and 5.08±1.37 µmol CO2 m-2 s-1 for poplars in the growing season. However, during the dormant season the soil sites with willow emitted 2.54±0.81 µmol CO2 m-2 s-1 and with poplar 2.07±0.56 µmol CO2 m-2 s-1. The highest emission rates for the studied plantations were observed in July for both years 2013 and 2014, during which the highest air and soil temperatures were recorded. Correlations between soil emission of CO2 and some meteorological parameters and leaf characteristics were investigated for the years 2013 and 2014. For example, for the willow clone (Jorr) and poplar clone (Max 3), high correlations were found for each between their soil emission of CO2 and both soil temperature and moisture content. Fitted models can explain about 77 and 75% of the results for Jorr and Max 3 clones, respectively. Moreover, a model of leaf area (LA) can explain about 68.6% of soil CO2 emission for H275. Estimated models can be used as a gap-filling method, when field data is not available. The ratio between soil respiration and the combustion heat calculated from the extracted products per hectare was evaluated and compared for the study’s willow, poplar and rapeseed crops. The results show that poplar and willow SRF has a very low ratio of 183 kg CO2 GJ 1 compared to rapeseed, 738 kg CO2 GJ 1. The soil-column experiment showed that by continuing the SRF plantation at the As-contaminated site, remediation would need only about 3% of the time needed if the site was left as a fallow field. In order to understand the complex willow and poplar short rotation forestry production system, 50 key variables were identified and prioritized to describe the system as a step to enhance the success of such potentially sustainable projects. The MICMAC approach was used in order to find the direct and the indirect relationships between those parameters and to classify them into different clusters depending on their driving force and interdependency. From this, it can be summarized that in order to enhance the success of a SRF system, decision makers should be focussing on: ensuring a developed wood-fuel market, increasing farmers’ experience/training, improving subsidy regulations and recommending a proper harvesting year cycle. Finally, the impacts of land-use change and occupation on the ecosystem quality were assessed. Results show that establishing SRF plantations on degraded lands improved the ecosystem structural quality (ESQ) by about 43% and ecosystem functional quality (EFQ) by about 12%. Based on overall results, poplar and willow SRF biomass can be recommended as renewable and sustainable sources for bioenergy.

Despite the negative effects of fossil fuels on the environment, these remain as the primary contributors to the energy sector. In order to mitigate global warming risks, many countries aim at reducing greenhouse gas emissions. Bioenergy crops are being used as a substitute for fossil fuels and short rotation forestry is a prime example. In order to examine the sustainability of energy crops for fuel, typical European short rotation forestry (SRF) biomass, willow (Salix spp.) and poplar (Populus spp.) are examined and compared to rapeseed (Brassica napus L.) in respect to various aspects of soil respiration and combustion heat obtained from the extracted products per hectare. Various approaches are used to look at an As-contaminated site not only in the field but also in a soil-column experiment that examines the fate of trace elements in SRF soils, and in an analysis using MICMAC to describe the driving factors for SRF crop production. Based on the cause-effect chain, the impacts of land-use change and occupation on ecosystem quality are assessed when land-use is changed from degraded land (grassland) to willow and poplar SRF. A manual opaque dynamic closed chamber system (SEMACH-FG) was utilized to measure CO2 emissions at a willow/poplar short rotation forest in Krummenhennersdorf, Germany during the years 2013 and 2014, and at a rapeseed site in 2014. Short rotation forest soils showed higher CO2 emission rates during the growing season than the dormant season – with a CO2 release of 5.62±1.81 m-2 s-1 for willows and 5.08±1.37 µmol CO2 m-2 s-1 for poplars in the growing season. However, during the dormant season the soil sites with willow emitted 2.54±0.81 µmol CO2 m-2 s-1 and with poplar 2.07±0.56 µmol CO2 m-2 s-1. The highest emission rates for the studied plantations were observed in July for both years 2013 and 2014, during which the highest air and soil temperatures were recorded. Correlations between soil emission of CO2 and some meteorological parameters and leaf characteristics were investigated for the years 2013 and 2014. For example, for the willow clone (Jorr) and poplar clone (Max 3), high correlations were found for each between their soil emission of CO2 and both soil temperature and moisture content. Fitted models can explain about 77 and 75% of the results for Jorr and Max 3 clones, respectively. Moreover, a model of leaf area (LA) can explain about 68.6% of soil CO2 emission for H275. Estimated models can be used as a gap-filling method, when field data is not available. The ratio between soil respiration and the combustion heat calculated from the extracted products per hectare was evaluated and compared for the study’s willow, poplar and rapeseed crops. The results show that poplar and willow SRF has a very low ratio of 183 kg CO2 GJ 1 compared to rapeseed, 738 kg CO2 GJ 1. The soil-column experiment showed that by continuing the SRF plantation at the As-contaminated site, remediation would need only about 3% of the time needed if the site was left as a fallow field. In order to understand the complex willow and poplar short rotation forestry production system, 50 key variables were identified and prioritized to describe the system as a step to enhance the success of such potentially sustainable projects. The MICMAC approach was used in order to find the direct and the indirect relationships between those parameters and to classify them into different clusters depending on their driving force and interdependency. From this, it can be summarized that in order to enhance the success of a SRF system, decision makers should be focussing on: ensuring a developed wood-fuel market, increasing farmers’ experience/training, improving subsidy regulations and recommending a proper harvesting year cycle. Finally, the impacts of land-use change and occupation on the ecosystem quality were assessed. Results show that establishing SRF plantations on degraded lands improved the ecosystem structural quality (ESQ) by about 43% and ecosystem functional quality (EFQ) by about 12%. Based on overall results, poplar and willow SRF biomass can be recommended as renewable and sustainable sources for bioenergy.:Table of Contents Acknowledgements VI Abstract VII List of Figures IX List of Tables XI List of Appendix Tables XII List of Abbreviations XIII List of Abbreviations ...continued XIV 1. Background 1 1.1. General introduction 1 1.2. Soil organic carbon (SOC) 2 1.3. Soil respiration 4 1.4. Energy and bioenergy crops 5 1.5. Willow and poplar short rotation forestry 8 1.6. Degraded lands 10 1.8. Challenges 17 1.9. Objectives of this study 18 2. Methodology 19 2.1. Site Description 19 2.2. Environmental variables 22 2.3. Measuring CO2 emissions 23 2.3.1. Soil emission of CO2 23 2.3.2. Sensitivity of soil respiration to temperature (Q10) 25 2.4. Willow and poplar leaf traits 26 2.4.1. Measuring leaf area 26 2.4.2. Leaf Area Index (LAI) 27 2.4.3. Leaf sensitivity to high and low temperatures 28 2.5. Soil characteristics 30 2.5.1. Soil sampling 30 2.5.2. Soil Moisture Content % (SMC) by gravimetric method 31 2.5.3. Soil pH 31 2.5.4. Soil Cation Exchange Capacity (CEC) 31 2.5.5. Soil content of C, N, S, heavy metals and trace elements 31 2.5.6. Soil porosity 31 2.5.7. Soil pore water 32 2.5.8. Soil hydraulic conductivity (Kf) 32 2.6. Soil-column experiment 34 2.6.1. Experiment set-up 35 2.6.2. Distribution coefficients (Kd) 35 2.7. MICMAC approach 36 2.7.1. Selection of variables 36 2.7.2. Description of direct relationships 36 2.7.3. Classification of variables 37 2.8. Impacts of land-use change on the ecosystem quality 38 2.9. Computer software 40 3. Results and Discussion 41 3.1. Environmental conditions 41 3.1.1. Photosynthetically active radiation (PAR) 41 3.1.2. Soil temperature 42 3.1.3. Soil moisture content 43 3.2. Soil emission of CO2 46 3.2.1. CO2 emission from soil at the short rotation forestry site 46 3.2.2. Soil emission of CO2 during the day and the night 48 3.2.3. Cumulative emission of CO2 49 3.2.4. Comparison with other bioenergy crops 50 3.3. Q10 52 3.4. Willow and poplar Leaf Characteristics 54 3.4.1. Leaf Area Index (LAI) 54 3.4.2. Specific leaf area (SLA) 56 3.4.3. Leaf sensitivity to temperature 57 3.5. Correlations of soil CO2 emission with soil temperature and moisture content 59 3.6. Correlations of soil CO2 emission with plant parameters 65 3.7. Insights into soil respiration and combustion heat per area 67 3.7.1. Cumulative seasonal CO2 emission (CE) 68 3.7.2. Output energy 69 3.7.3. CO2(soil respiration) / Energy ratio 70 3.7.4. Global-warming potential (GWP) 72 3.8. Trace elements in soil 73 3.8.1. Solid-liquid partition coefficients (Kd) 74 3.8.2. Estimating time of remediation 78 3.9. Identification and Prioritization of Key Parameters for Willow and Poplar Short Rotation Forestry (SRF) Production System 82 3.9.1. Based on direct influence/dependence map: 85 3.9.2. Based on indirect influence/dependence map: 87 3.10. Impacts of Land-use Change on the Ecosystem Quality 93 4. Conclusions and Recommendations 101 5. References 102 Appendix 118

[Truncated abstract] Insufficient water use by annual crop and pasture species leading to costly rises in saline watertables has prompted research into potentially profitable deep-rooted perennial species in the Western Australian wheatbelt. Native mallee eucalypts are currently being developed as a short-rotation coppice crop for production of leaf oils, activated carbon and bio-electricity for low rainfall areas (300—450 mm) too dry for many of the traditional timber and forage species. The research in this study was aimed at developing a knowledge base necessary to grow and manage coppiced mallee eucalypts for both high productivity and salinity control. This firstly necessitated identification of suitable species, climatic and site requirements favourable to rapid growth, and understanding of factors likely to affect yield of the desirable leaf oil constituent, 1,8-cineole. This was undertaken using nine mallee taxa at twelve sites with two harvest regimes. E. kochii subsp. plenissima emerged as showing promise in the central and northern wheatbelt, particularly at a deep acid sand site (Gn 2.61; Northcote, 1979), so further studies focussed on physiology of its resprouting, water use and water-use efficiency at a similar site near Kalannie. Young E. kochii trees were well equipped with large numbers of meristematic foci and adequate root starch reserves to endure repeated shoot removal. The cutting season and interval between cuts were then demonstrated to have a strong influence on productivity, since first-year coppice growth was slow and root systems appeared to cease in secondary growth during the first 1.5—2.5 years after cutting. After decapitation, trees altered their physiology to promote rapid replacement of shoots. Compared to uncut trees, leaves of coppices were formed with a low carbon content per unit area, and showed high stomatal conductance accompanied by high leaf photosynthetic rates. Whole-plant water use efficiency of coppiced trees was unusually high due to their fast relative growth rates associated with preferential investments of photosynthates into regenerating canopies rather than roots. Despite relatively small leaf areas on coppice shoots over the two years following decapitation, high leaf transpiration rates resulted in coppices using water at rates far in excess of that falling as rain on the tree belt area. Water budgets showed that 20 % of the study paddock would have been needed as 0—2 year coppices in 5 m wide twin-row belts in order to maintain hydrological balance over the study period. Maximum water use occurred where uncut trees were accessing a fresh perched aquifer, but where this was not present water budgets still showed transpiration of uncut trees occurring at rates equivalent to 3—4 times rainfall incident on the tree belt canopy. In this scenario, only 10 % of the paddock surface would have been required under 5 m wide tree belts to restore hydrological balance, but competition losses in adjacent pasture would have been greater