http://hdl.handle.net/1842/1634 2013-05-21T15:04:52Z http://hdl.handle.net/1842/6574 Title: Understanding the effects of drought upon carbon allocation and cycling in an Amazonian rain forest Authors: Metcalfe, Daniel Benjamin Abstract: The Amazon rain forest plays an important role in regional and global biogeochemical cycling, but the region may undergo an increase in the frequency and severity of drought conditions driven by global climate change, regional deforestation and fire. The effects of this drought on carbon cycling in the Amazon, particularly below-ground, are potentially large but remain poorly understood. This thesis examines the impacts of seasonal and longer-term drought upon ecosystem carbon allocation and cycling at an Amazon rain forest site with a particular focus upon below-ground processes. Measurements are made at three one-hectare forest plots with contrasting soil type and vegetation structure, to observe responses across a range of Amazon primary forest types. A fourth plot is subjected to partial rainfall exclusion to permit measurement of forest responses to a wider range of soil moisture levels than currently exists naturally. An analysis of the number of samples required to accurately quantify important ecosystem carbon stocks and fluxes is used to guide the sampling strategy at the field site. Quantifying root dynamics, in particular, presents methodological challenges. Thus, I critically review existing methods, and develop techniques to accurately measure root standing biomass and production. Subsequently, these techniques are used to record root responses, in terms of standing biomass, production, morphology, turnover and nutrient content, to variation in soil moisture across the four rain forest plots. There is substantial environmental variation in root characteristics. However, several responses remain consistent across plots: root production of biomass, length, and surface area, is lower where soil is dry, while root length and surface area per unit mass show the opposite pattern. The other major component of the below-ground carbon cycle is soil carbon dioxide efflux. I partition this efflux, on each plot, into contributions from organic ground surface litter, roots and soil organic matter, and investigate abiotic and biotic causes for observed differences within and between plots. On average, the percentage contribution of soil organic matter respiration to total soil carbon dioxide efflux declines during the dry season, while root respiration contribution displays the opposite trend. However, spatial patterns in soil respiration are not directly attributable to variation in either soil moisture or temperature. Instead, ground surface organic litter mass and root mass account for 44 % of observed spatial heterogeneity in soil carbon dioxide efflux. Finally, information on below-ground carbon cycling is combined with aboveround data, of canopy dynamics and stem wood production and mortality, to analyze the potential effects of drought upon carbon cycling in an Amazon forest ecosystem. Comparison of the rainfall exclusion plot with a similar, but unmodified, control plot reveals potentially important differences in tree carbon allocation, mortality, reproduction, soil respiration and root dynamics. The apparent net consequence of these changes is that, under drier conditions, the amount of CO2 moving out of the forest and into the atmosphere is diminished. This synthesis of above-ground and below-ground data advances understanding of carbon cycling in rain forests, and provides information which should allow more accurate modelling of the response of the Amazon region to future drought. Additional measurements at other sites, and of other ecosystem carbon fluxes, should further refine modelling predictions. 2007-11-27T00:00:00Z http://hdl.handle.net/1842/6506 Title: Modelling the effects of genetic line and feeding system on methane emissions from dairy systems Authors: Bell, Matthew Abstract: Dairy cattle make a significant contribution to global methane emissions. Milking cows in the UK make up about a fifth of the total cattle population, with Holstein-Friesian cows being the most common breed. Investigating ways to minimise methane, a potent greenhouse gas (GHG) produced by dairy cows from enteric fermentation and manure, has gained importance in recent years due its role in climate change. Currently, GHG emissions from UK dairy farming are predicted using the Intergovernmental Panel on Climate Change (IPCC) Tier II methodology. The IPCC Tier II methodology and statistical prediction equations from the literature were evaluated for their ability to reliably model methane output using data from the Langhill Holstein-Friesian experimental herd. The Langhill dairy herd is on a long-term breeding and feeding systems experiment, and cows are on average 88% North American Holstein genes. The production systems within the herd represent a range of dairy systems that may be found commercially. Therefore, production values were assumed to be representative of those that could be found in the commercial Holstein-Friesian population, so factors affecting system methane emissions and appropriate mitigation options could be investigated. Prediction equations using dry matter (DM) intake and gross energy intake as input values were the most appropriate equations for reliably estimating daily enteric methane output. However, if DM intake values are not available, the IPCC Tier II method was found to provide a suitable prediction of methane emissions over a cow‘s lactation and lifetime. This study found that GHG emissions from enteric fermentation and manure, expressed as carbon dioxide equivalents (CO2-eq.), account for about 66% of dairy system CO2-eq. emissions, with enteric methane output being the main contributor (34% of system CO2-eq. emissions). Breeding for increased kilograms of milk fat plus protein production was shown to help reduce dairy system methane emissions. Cows of predominantly North American Holstein genes in this study produced more milk when fed a diet with a low proportion of forage and had lower GHG emissions and land requirement per kilogram energy corrected milk than similar cows fed a diet with a higher proportion of forage. Strategies to mitigate GHG emissions (including methane) and the environmental impact of dairy systems should seek to select animals that better utilise their feed intake to meet their genetic potential for milk production. 2011-06-28T00:00:00Z http://hdl.handle.net/1842/6405 Title: Effectiveness and Impacts of Ecological Fiscal Transfers and Payments for Environmental Services: A Case Study of Shengnongjia National Nature Reserve Authors: Li, Mingmei Abstract: The use of economic instruments (EIs) for conserving ecosystem services is gaining increasing attention. However, the literature available on the analysis and assessment of EIs’ effectiveness and impacts focuses mostly on the experience in developed countries. In recent years, there is growing interest among developing countries, including China, in applying EIs in conserving biodiversity and other ecosystem services. Specific challenges faced by developing countries are not the same with those by the developed world. So far, not much has been done in analysing and assessing EIs effectiveness and their interaction with the specific challenges in the developing context, such as poverty alleviation. This dissertation looks into the performance of two EIs, i.e. Ecological Fiscal Transfers (EFT) and Payments for Environmental Services (PES), in achieving conservation effectiveness and their economic and social impacts, through a case study on the Shengnongjia National Nature Reserve in China. It is found that the conservation effectiveness (like additionality and leakage), economic impacts (like income, jobs, and fiscal revenues) and social impacts (like distributive fairness) fall short of devised goals to some extent. The case study also found that ignoring economic and social dimensions of EIs application may lead to unexpected negative consequences on conservation effectiveness. Besides, the paper discusses some open questions related to institutional preconditions for applying EIs and PES in developing context which deserve further research in the future. The findings drawn from this case study provide a test and confirmation of the academic proposal that equity and poverty issue should be taken into account in the process of designing and using EIs, in particular in developing countries. 2012-11-29T00:00:00Z http://hdl.handle.net/1842/6404 Title: Sustainable Transport Development for Accra: Critiquing Ideologies and Unraveling Priorities Authors: Anyetei-Anum, Dzifa Abstract: It is questionable whether decentralization or economic liberalization policies form good foundations for good governance in a developing country. Ghana’s first National Transport Policy was drafted in 2008. A prominent theme in this policy document is ensuring sustainable development of urban public transportation, through, among other things, good governance. The document, however, is built within the contextual frameworks of Ghana’s Poverty Strategy Papers, which espouse decentralization and economic liberalization policies. It is argued that these policies are incompatible with the transport policy agenda for sustainable development as they are not fertile ground for breeding good governance. However they are conducive to ensuring the premier priority within Accra’s public transportation system is met – which is maintaining employment and thus upholding livelihoods. 2012-11-01T00:00:00Z