Doctoral and Masters Theses http://hdl.handle.net/11019/751 2017-11-07T00:26:27Z 2017-11-07T00:26:27Z Walsh, Aidan http://hdl.handle.net/11019/1104 2017-03-09T02:01:32Z 2016-06-01T00:00:00Z

Title: Methods for the Identification of Important Areas of Plant Diversity in Ireland Authors: Walsh, Aidan Abstract: The loss of biodiversity is an on-going global issue that not only results in the extinction of species but also threatens the ecosystem services and goods on which humanity depends. The global community has responded with ambitious targets to halt and reverse the loss of biodiversity. The causes of biodiversity loss are well understood and conservation measures can be deployed to protect biodiversity. However, conservation resources are limited and to be effective must be targeted to the most important areas of biodiversity. Using vascular plant distribution records for Ireland this research examined the distribution of plant species of conservation concern to determine if additional conservation measures should be targeted to these species. In an attempt to aid the targeting of conservation measures to the most important areas of biodiversity this research also investigated methods for the identification of priority areas for plant conservation. In an initial study vascular plant distribution records were collated and mapped for the island of Ireland. The tetrad scale (2km x 2km) data provided incomplete coverage for Ireland. Records for plant species of conservation concern were extracted and mapped at the tetrad scale for Ireland. The coincidence of the locations of the species of conservation concern and the distribution of areas designated for the protection of biodiversity in Ireland was examined. Between 22 – 40% of the locations of these species were found to occur outside of designated areas and for some individual species all of the locations occurred outside designated areas. The results indicated the importance of both designated areas and the wider countryside for biodiversity conservation. In particular the presence of species of conservation concern in non-designated areas highlights the need for conservation measures outside of designated areas. Subsequent research investigated a method for the identification of the most important areas of plant diversity at the tetrad and hectad (10km x 10km) scales in Ireland. A criteria-based scoring method was developed to characterise the landscape in terms of conservation value and identify the important areas of plant diversity. The effect of each of the criteria on priority area identification and on the representation of species (that is the extent to which species occur within a set of sites) within the priority areas was examined. The outcomes of this research identified a combination of criteria that allowed the identification of priority areas of high conservation value that contained a high species representation level. A subsequent investigation examined an alternative method for the identification of priority areas for conservation. A complementarity-based method using linear programming was used to identify the minimum number of priority areas in which species representation was guaranteed. Additional linear programs were formulated to identify restricted numbers of priority areas in which species representation was maximised. This research also developed a means of incorporating the outputs of the scoring method into the linear programming method. A combination of the plant distribution data, spatial environmental data, and a logistic regression method was used to build models to predict the distribution of the plant species of conservation concern group (SCC). The associations between the environmental data and SCC occurrence were examined and the predictive performance of both models was investigated using plant records in County Waterford. To conclude, this research showed that the tetrad-scale plant distribution coverage is patchy for most of Ireland. However, even with incomplete data the research indicated that conservation measures could be targeted to sites outside of protected areas. The plant distribution data can be used to characterise the landscape in terms of conservation value and both the scoring method and linear programming method can be used to identify priority areas for conservation. The scoring method and linear programming method can be combined to efficiently identify priority areas of high conservation value and the research showed the potential use of species distribution modelling for conservation planning in Ireland. Description: Doctoral Thesis

2016-06-01T00:00:00Z Sevillano, Ignacio http://hdl.handle.net/11019/1098 2017-01-10T02:01:34Z 2016-06-01T00:00:00Z

Title: Morphological and physiological responses of Fagus sylvatica and Quercus robur seedlings to light availability Authors: Sevillano, Ignacio Abstract: The need to develop forest management systems other than clearfelling has resulted in a requirement for improved understanding of the potential of continuous cover forestry (CCF). One suggested method for the conversion of forest stands into CCF systems and for bringing under-performing forests into productivity is thinning in conjunction with underplanting. This study was an attempt to provide information on species suitability for underplanting of two important trees in European forestry: pedunculate oak (Quercus robur L.) and European beech (Fagus sylvatica L.). To determine the morphological, physiological and growth responses of these two species to different light conditions, beech and oak seedlings previously grown at full light for two years were covered by shading nets that provide different shade levels (62%, 51% or 28% of full light) or continued to be exposed to full light. The different shade levels were intended to mimic a range of underplanted conditions and the process of acclimation to shade was studied to provide information on the ecology and adaptation of underplanted seedlings. In addition to the controlled-shade experiment another study to determine the physiological responses of beech natural regeneration to shade was conducted under natural light conditions (from open gaps to closed canopy). Both oak and beech displayed similar acclimation in response to shade for most of the traits investigated. At the plant level, seedling acclimation to shade included higher biomass allocation to above than below-ground parts and greater energy investment on height than diameter growth. At the leaf level, seedlings grown under shade reduced their leaf thickness and photosynthetic rates per unit area and increased their specific leaf area. This increase in specific leaf area seems to be one mechanism that allows seedlings to perform well under shade conditions. Another acclimation to low light conditions was to increase the efficiency of the photosystem II under shade. Photosynthetic rates were higher and leaves were retained for longer in seedlings grown at full light than under shade. Hence, this probably led to a greater growth in the full light than under shade. Despite this greater growth at full light, the results of this study suggest that beech and oak seedlings would be able to acclimate and perform well if underplanted below overstories that reduce the available light to as low as 28% of full light without having any significant adverse effect on the quality of the final crop. Description: Doctoral thesis

2016-06-01T00:00:00Z Di Fenza, Mauro http://hdl.handle.net/11019/592 2014-06-10T01:01:16Z 2013-01-01T00:00:00Z

Title: Examining the physiological and genetic response of maize to low temperature conditions Authors: Di Fenza, Mauro Abstract: Maize (Zea mays) is an emerging forage crop in Ireland, originating in warmer climates. Under Irish climate conditions establishment can be problematic due to low soil temperatures at early stages of establishment. Maize varieties with improved chilling tolerance have been developed and are on the market, but maize in Ireland is still established under plastic and further varietal improvements are required to make this crop more economically viable. To date, varieties are selected principally by phenotypic traits rather than genetic response. Investigation of the physiological and genetic response of maize towards cold/chilling stress at early developmental stage, in particular the response of developing maize roots to cold stress, can make a contribution towards the understanding of the molecular mechanisms conferring plant cold tolerance. The objectives of this study were aimed to create, at first, an experimental design to test the physiological response to low temperatures, under controlled environmental conditions, of various commercial maize cultivars adapted to grow in temperate climates. Responses to abiotic stresses such as cold involve changes in gene expression, therefore, once indentified the hybrids showing contrasting degrees of cold tolerance, these were profilied to examine gene expression and identify possible cold regulated genes. The physiological experiments on twelve maize varieties identified four genotypes with contrasting cold tolerance. Microarray analysis profiling these varieties was used to identify up and down regulated genes under cold/chilling conditions. The stress induced by the cold temperature in the genotypes Picker, PR39B29, Fergus and Codisco was reflected only on the expression profiles of the two varieties with superior cold tolerance, Picker and PR39B29. No significant changes in expression were observed in Fergus and Codisco in response to cold stress. The overall number of genes up and down regulated in the two cold tolerant varieties amounted to 69, which were, however, divided in a group of 39 genes in PR39B29 and 30 genes in Picker, as the two varieties exhibited two different trancriptomic patterns in which only four genes (RNA binding protein, pathogenesis-related protein 1 and two unknown proteins) were shared, although not all with the same degree of regulation. No cold regulated genes ware detected. The gene expression of the four-shared genes was further investigated with qRT-PCR in order to estimate the expression pattern over time. Five time points were used to analyse the expression trend of the genes. The gene expression was not maintained over the five time points, but it was subjected to fluctuation. However, with the exception of the RNA binding protein gene, the expression pattern was similar between the two varieties, indicating a common response to chilling stress. Description: peer-reviewed

2013-01-01T00:00:00Z O'Flynn, Cornelius J. http://hdl.handle.net/11019/478 2013-12-17T02:02:29Z 2013-05-01T00:00:00Z

Title: The Impact of Chemically Amended Pig Slurry on Surface Runoff, Leachate and Greenhouse Gasses Authors: O'Flynn, Cornelius J. Abstract: In Ireland, the pig industry is concentrated in a small number of counties. Pig farms typically have a high stocking rate. Therefore, the disposal of slurry in a cost-effective and environmentally-responsible way is a serious issue for farmers. Slurry is commonly applied to land, but this may not be possible if the land is at, or approaching, phosphorus (P) saturation. As pig farmers dispose of slurry in the vicinity of their properties, most of the nearby land is at P saturation, so alternative treatment methods need to be utilised (e.g. constructed wetlands, anaerobic digestion, filtration) or the slurry needs to be transported to another location. These alternatives are not currently financially viable in Ireland. Existing legislation (S.I. 610 of 2010) and recent changes in the implementation of legislation governing the timing and quantities of slurry that may be applied to land, means that pig farmers will no longer be able to exceed the maximum legal application rate to land (from January 2017). European policy aiming to intensify pig production will only accentuate this problem. If pig farmers are forced, in exceptional circumstances, to land apply slurry to unsuitable land, surface and subsurface losses of nutrients and suspended solids (SS) may occur. This could be potentially problematic if the land is located in a critical source area (CSA), an area that is highly likely to pollute receiving waters. In these circumstances, a possible novel solution is to chemically amend the pig slurry prior to landspreading. This would mean that pig farmers may, in exceptional circumstances, utilise the land in the vicinity of their farms for landspreading, without releasing excessive nutrients and SS into receiving waters. However, knowledge gaps exist concerning the type of amendments to be used, the characteristics of the soil on which they can be most effectively used, and their impact on incidental (short-term) and chronic (long-term) losses of nutrients, SS and greenhouse gas (GHG) to surface and subsurface water and the atmosphere. Therefore, the aims of this project were to: (1) identify the most appropriate chemical amendments, and their addition rates, to reduce P losses in runoff from pig slurry based on effectiveness, cost and feasibility; (2) investigate the impacts of these chemical amendments on nutrient losses in leachate, soil properties and GHG emissions; and (3) identify suitable soil types on which to landspread chemically-amended pig slurry. Laboratory bench-scale experiments were designed to identify the amendments which had the potential to reduce P in overland runoff and to quantify the stoichiometric rates at which to add them to the slurry. Based on effectiveness, cost and feasibility, the amendments identified were alum, which reduced dissolved reactive phosphorus (DRP) in overlying water by 86%, poly-aluminium chloride (PAC) (73%) and ferric chloride (FeCl3) (71%). Following these bench-scale experiments, rainfall simulation experiments were conducted to quantify the impact of chemical amendments to slurry on surface runoff losses at various time intervals from the time of application. Poly-aluminium chloride performed best in these experiments. For the first time, the effect of these amendments on GHG emissions, soil properties and leachate was also examined. Chemical amendment did not adversely affect GHG emissions, soil properties or leachate from pig slurry, but FeCl3 increased nitrous oxide (N2O) and carbon dioxide (CO2) losses. Finally, a 3-mo incubation experiment was conducted using a range of soil types to examine the effect of amendments on the long-term plant availability of P in soil and P solubility. Alum reduced more water extractable P than PAC, but also resulted in less plant available P. Considering cost, surface runoff and subsurface leachate losses, GHG emissions and impacts on soil chemistry, PAC was found to be the most suitable amendment with which to chemically amend pig slurry. There is the potential, in combination with existing programmes of measures, to employ chemical amendment as a measure to mitigate the environmental impact arising from the landspreading of pig slurry. This should be conducted in targeted areas of the CSA and should take into account soil type and its chemical properties. Before implementation, these tests must first be validated in long-term testing at field-scale over a wide variety of soil types, and include repeated application and incorporation. At present, there is no provision in legislation for chemical amendments to be used as a mitigation measure in the land application of pig slurry, but if they are to be utilised, a regulatory framework will need to be introduced by the relevant bodies. Description: peer-reviewed; Doctoral thesis

2013-05-01T00:00:00Z