Botany http://hdl.handle.net/2262/19 2013-05-20T13:36:51Z 2013-05-20T13:36:51Z HODKINSON, TREVOR ROLAND http://hdl.handle.net/2262/64038 2012-06-27T11:58:27Z 2011-01-01T00:00:00Z

Title: Marriage exchanges, seed exchanges, and the dynamics of manioc diversity Author: HODKINSON, TREVOR ROLAND Abstract: The conservation of crop genetic resources requires understanding the different variables-cultural, social, and economic-that impinge on crop diversity. In small-scale farming systems, seed exchanges represent a key mechanism in the dynamics of crop genetic diversity, and analyzing the rules that structure social networks of seed exchange between farmer communities can help decipher patterns of crop genetic diversity. Using a combination of ethnobotanical and molecular genetic approaches, we investigated the relationships between regional patterns of manioc genetic diversity in Gabon and local networks of seed exchange. Spatially explicit Bayesian clustering methods showed that geographical discontinuities of manioc genetic diversity mirror major ethnolinguistic boundaries, with a southern matrilineal domain characterized by high levels of varietal diversity and a northern patrilineal domain characterized by low varietal diversity. Borrowing concepts from anthropology-kinship, bridewealth, and filiation-we analyzed the relationships between marriage exchanges and seed exchange networks in patrilineal and matrilineal societies. We demonstrate that, by defining marriage prohibitions, kinship systems structure social networks of exchange between farmer communities and influence the movement of seeds in metapopulations, shaping crop diversity at local and regional levels. Description: PUBLISHED

2011-01-01T00:00:00Z MITCHELL, FRASER JOHN GRAY http://hdl.handle.net/2262/63709 2012-11-05T16:26:57Z 2012-01-01T00:00:00Z

Title: A 1000-year reconstruction of summer precipitation from Ireland: Calibration of a peat-based palaeoclimate record Author: MITCHELL, FRASER JOHN GRAY Abstract: Calibration of proxy climate records is well-established for annually resolved proxies such as tree rings, but it has not been attempted for non-annually resolved proxies such as those from peatland surface wetness records. Several previous studies have suggested that peatland surface wetness is primarily driven by warm season moisture balance and implied a potential for producing calibrated records of deficit or precipitation. This paper presents a high-resolution testate amoebae analysis of a peat record from central Ireland covering the last c.1000 years, and provides the first attempt to produce a calibrated record of past precipitation from a peat record. Past water table depth was reconstructed using a transfer function applied to contiguous samples for the top 1m of the profile. The chronology was constrained by a series of radiocarbon ages (including ‘bomb-spike’ ages) and spheroidal carbonaceous particles. Correlations between reconstructed water tables and meteorological records (1958-1995) of precipitation and deficit were strongly positive and were used to reconstruct precipitation and deficit from the last 1000 years. Validation using earlier meteorological records was hampered by very low peat accumulation rates, but suggested the summer precipitation and deficit reconstructions were more robust than a reconstruction of annual precipitation. The summer precipitation reconstruction suggests that the period AD1400-1850 experienced higher summer rainfall than for much of both the preceding 400 years and the last 150 years. The change in regime from low to high summer rainfall may be attributed to changes in the summer North Atlantic Oscillation. Combined with tree ring and speleothem records of winter NAO, this suggests a major change in seasonality of precipitation in far western Europe between the Medieval Climate Anomaly and the Little Ice Age. The MCA was characterised by dry summers and wet winters, whilst the LIA had wet summers and dry winters. Calibration of peat surface wetness records using meteorological records holds much potential for the future and may lead to improved insights into seasonal precipitation and water balance changes. This study was limited by slow accumulation rates leading to low temporal resolution for the late 19th and early 20th century part of the record. Further development of the technique will require more highly temporally resolved records of change over the whole of the instrumental time period to allow a full calibration and validation approach to be applied. Description: PUBLISHED

2012-01-01T00:00:00Z VAN GROENIGEN, CORNELIS JAN http://hdl.handle.net/2262/62561 2012-03-07T10:17:51Z 2012-01-01T00:00:00Z

Title: An agronomic assessment of greenhouse gas emissions from major cereal crops Author: VAN GROENIGEN, CORNELIS JAN Abstract: Agricultural greenhouse gas (GHG) emissions contribute approximately 12% to total global anthropogenic GHG emissions. Cereals (rice, wheat, and maize) are the largest source of human calories, and it is estimated that world cereal production must increase by 1.3% annually to 2025 to meet growing demand. Sustainable intensification of cereal production systems will require maintaining high yields while reducing environmental costs. We conducted a meta-analysis (57 published studies consisting of 62 study sites and 328 observations) to test the hypothesis that the global warming potential (GWP) of CH4 and N2O emissions from rice, wheat, and maize, when expressed per ton of grain (yield-scaled GWP), is similar, and that the lowest value for each cereal is achieved at near optimal yields. Results show that the GWP of CH4 and N2O emissions from rice (3757 kg CO2 eq ha-1 season-1) was higher than wheat (662 kg CO2 eq ha-1 season-1) and maize (1399 kg CO2 eq ha-1 season-1). The yield-scaled GWP of rice was about four times higher (657 kg CO2 eq Mg-1) than wheat (166 kg CO2 eq Mg-1) and maize (185 kg CO2 eq Mg-1). Across cereals, the lowest yield-scaled GWP values were achieved at 92% of maximal yield and were about twice as high for rice (279 kg CO2 eq Mg-1) than wheat (102 kg CO2 eq Mg-1) or maize (140 kg CO2 eq Mg-1), suggesting greater mitigation opportunities for rice systems. In rice, wheat and maize, 0.68%, 1.21%, and 1.06% of N applied was emitted as N2O, respectively. In rice systems, there was no correlation between CH4 emissions and N rate. In addition, when evaluating issues related to food security and environmental sustainability, other factors including cultural significance, the provisioning of ecosystem services, and human health and well-being must also be considered. Description: PUBLISHED

2012-01-01T00:00:00Z KELLY, DANIEL LUCIUS http://hdl.handle.net/2262/61865 2012-01-27T15:58:16Z 2010-01-01T00:00:00Z

Title: Hondurodendron, a new monotypic genus of Aptandraceae from Honduras. Author: KELLY, DANIEL LUCIUS Abstract: Hondurodendron C. Ulloa, Nickrent, Whitef. & D. Kelly, a new monotypic genus endemic to Honduras, is here described and illustrated. The new species, H. urceolatum C. Ulloa, Nickrent, Whitef. & D. Kelly, is a dioecious tree, distinguished by its minute flowers borne on densely tomentose inflorescences, unique anthers opening by three valves, and a characteristic fruit totally enveloped by the accrescent calyx, which projects beyond the fruit. A molecular analysis based on four genes (nuclear small subunit [SSU] ribosomal DNA [rDNA], chloroplast rbcL, matK, and accD) placed this genus in a clade with Aptandra Miers, Harmandia Pierre ex Baill., Chaunochiton Benth., and Ongokea Pierre in the family Aptandraceae Miers. Resumen: Se describe e ilustra un nuevo género monotípico Hondurodendron C. Ulloa, Nickrent, Whitef. & D. Kelly endémico de Honduras. La nueva especie H. urceolatum C. Ulloa, Nickrent, Whitef. & D. Kelly es un árbol dioico, que se distingue por las flores diminutas en inflorescencias densamente tomentosas, las anteras únicas que se abren por tres valvas y un fruto característico totalmente encerrado por el cáliz acrescente que se proyecta sobre éste. Un análisis molecular con cuatro genes (SSU ADN ribosómico nuclear, rbcL del cloroplasto, matK y accD) ubica al género en un clado junto con Aptandra Miers, Harmandia Pierre ex Baill., Chaunochiton Benth. y Ongokea Pierre en la familia Aptandraceae Miers. Description: PUBLISHED

2010-01-01T00:00:00Z WILLIAMS, MICHAEL LEONARD JONES, MICHAEL BEVAN ABDALLA, MOHAMED http://hdl.handle.net/2262/59824 2012-10-03T16:24:48Z 2011-01-01T00:00:00Z

Title: Testing DNDC model for simulating soil respiration and assessing the effects of climate change on the CO2 gas flux from Irish agriculture Author: WILLIAMS, MICHAEL LEONARD; JONES, MICHAEL BEVAN; ABDALLA, MOHAMED Abstract: Simulation models can be valuable to investigate potential effects of climate change on greenhouse gas emissions from terrestrial ecosystems. DNDC (the DeNitrification-DeComposition model) was tested against observed soil respiration data from adjacent pasture and arable fields in the Irish midlands. The arable field was converted from grassland approximately 50 years ago and managed since 2003 under two different tillage systems; conventional and reduced tillage. Both fields were located on the same soil type, classified as a free draining sandy loam soil derived from fluvial glacial gravels with low soil moisture holding capacity. Soil respiration measurements were made from January 2003 to August 2005. Three climate scenarios were investigated, a baseline of measured climatic data from a weather station at the field site, and high and low temperature sensitivity scenarios predicted by the Community Climate Change Consortium for Ireland (C4I) based on the Hadley Centre Global Climate Model (HadCM3) and the Intergovernment Panel on Climate Change (IPCC) A1B emission scenario. The aims of this study were to use measured soil respiration rates to validate the DNDC model for estimating CO2 efflux from these key Irish soils, investigate the effects of future climate change on CO2 efflux and estimate the efflux uncertainties due to using different future climate projections. The results indicate that the DNDC model can reliably estimate soil respiration from the two fields examined. The model underestimated annual measured CO2 efflux from the pasture by only13% (model efficiency: ME = 0.6; root mean square error: RMSE = 1.9 and mean absolute error: MAE = 6.3) and that from the arable conventional and reduced tillage by 9% (ME = 0.6; RMSE = 1.6 and MAE = 2.4) and 8% (ME = 0.23; RMSE = 1.8 and MAE = 2.9), respectively. Short-term land use change had no significant effects on CO2 effluxes from soil. Using the high temperature sensitive scenario, future C effluxes would increase by 15% for the pasture and 14 and 16% for the arable conventional and reduced tillage systems, respectively. However, under the low temperature sensitive scenario, lower increases in the C efflux of 6% for the pasture and 5% for the arable field were predicted. The calculated annual CO2 efflux uncertainties for using the high and low temperature sensitivity scenarios were 9% for the pasture and 8% for the arable field. Description: PUBLISHED

2011-01-01T00:00:00Z STOUT, JANE CATHERINE POWER, EILEEN http://hdl.handle.net/2262/57425 2011-09-27T20:06:06Z 2011-01-01T00:00:00Z

Title: Organic dairy farming: impacts on insect flower interaction networks and pollination Author: STOUT, JANE CATHERINE; POWER, EILEEN Abstract: 1. Pollination interactions comprise a network of connections between flowers and insect visitors. They are crucial for reproductive success in many angiosperms but are threatened by intensive agricultural practices. Although less intensive approaches, including organic farming, could improve farmland biodiversity, it is not clear whether or not these approaches enhance wild plant pollination and the stability of insect–flower interaction networks. 2. We investigated the effects of organic vs. conventional farming on insect–flower interaction network size and structure, bee and hoverfly diversity, and pollination in 10 pairs of organic and conventional dairy farms in the Republic of Ireland. 3. We found that insect–flower interaction networks on organic farms were larger and more asymmetrically structured than networks on conventional farms. Overall, however, networks contained fewer taxa and niche overlap and plant ⁄ animal ratios were relatively low compared with previously documented insect–flower interaction networks. Organic farms did attract higher numbers of bees partly because of higher floral abundances (mainly Trifolium sp.). Hoverfly evenness was greater in organic farms but neither abundance, richness nor evenness was related to floral abundance, suggesting organic farms provide additional resources for hoverflies. Pollination of Crataegus monogyna hawthorn was higher on organic farms, although pollen deposition was limited. 4. Synthesis and applications. Organic dairy farming can increase the size and alter the structure of insect–flower interaction networks. However, network stability was not improved and all networks (organic and conventional) were vulnerable because of their small size, low niche overlap and low plant ⁄ animal ratios. Nonetheless, organic farming provided more flowers that attracted more flower visitors and improved pollination of C. monogyna. We suggest that strategic management of important flowers for pollinators in hedgerows and pastures should be endorsed in agri-environmental schemes. Sowing Trifolium spp., and allowing these plants to flower, could benefit bees, but more research into hoverfly ecology is necessary before realistic conservation recommendations can be made for this group. We conclude that organic farming, although not the solution in its present form, can benefit insect biodiversity, insect–flower interaction networks and insect-mediated pollination. Description: PUBLISHED

2011-01-01T00:00:00Z JONES, MICHAEL BEVAN http://hdl.handle.net/2262/57383 2011-07-01T15:10:24Z 2011-01-01T00:00:00Z

Title: Dissolved carbon leaching from soil is a crucial component of the net ecosystem carbon balance Author: JONES, MICHAEL BEVAN Abstract: Estimates of carbon leaching losses from different land use systems are few and their contribution to the net ecosystem carbon balance is uncertain. We investigated leaching of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and dissolved methane (CH4), at forests, grasslands, and croplands across Europe. Biogenic contributions to DIC were estimated by means of its δ13C signature. Leaching of biogenic DIC was 8.3±4.9 g m−2 yr−1 for forests, 24.1±7.2 g m−2 yr−1 for grasslands, and 14.6±4.8 g m−2 yr−1 for croplands. DOC leaching equalled 3.5±1.3 g m−2 yr−1 for forests, 5.3±2.0 g m−2 yr−1 for grasslands, and 4.1±1.3 g m−2 yr−1 for croplands. The average flux of total biogenic carbon across land use systems was 19.4±4.0 g C m−2 yr−1. Production of DOC in topsoils was positively related to their C/N ratio and DOC retention in subsoils was inversely related to the ratio of organic carbon to iron plus aluminium (hydr)oxides. Partial pressures of CO2 in soil air and soil pH determined DIC concentrations and fluxes, but soil solutions were often supersaturated with DIC relative to soil air CO2. Leaching losses of biogenic carbon (DOC plus biogenic DIC) from grasslands equalled 5–98% (median: 22%) of net ecosystem exchange (NEE) plus carbon inputs with fertilization minus carbon removal with harvest. Carbon leaching increased the net losses from cropland soils by 24–105% (median: 25%). For the majority of forest sites, leaching hardly affected actual net ecosystem carbon balances because of the small solubility of CO2 in acidic forest soil solutions and large NEE. Leaching of CH4 proved to be insignificant compared with other fluxes of carbon. Overall, our results show that leaching losses are particularly important for the carbon balance of agricultural systems. Description: PUBLISHED

2011-01-01T00:00:00Z EGAN, PAUL http://hdl.handle.net/2262/56528 2011-06-08T11:29:26Z 2011-01-01T00:00:00Z

Title: Meconopsis autumnalis and M. manasluensis (Papaveraceae), two new species of Himalayan poppy endemic to central Nepal with sympatric congeners Author: EGAN, PAUL Abstract: Two new species from Nepal, Meconopsis autumnalis and M. manasluensis, are described and illustrated with notes on diagnostic characters used to distinguish them from allied species. Sympatric speciation and the mechanisms to reproductively isolate the new species are discussed. In M. autumnalis, reproductive isolation from the widespread M. paniculata is the result of a shift in flowering phenology, whereas possible mechanisms preventing cross-fertilisation between M. manasluensis and the sympatric species M. pinnatifolia remain unclear. Description: PUBLISHED

2011-01-01T00:00:00Z STOUT, JANE CATHERINE http://hdl.handle.net/2262/55444 2011-09-27T20:07:21Z 2011-01-01T00:00:00Z

Title: Pollination ecology in the 21st century: Key Questions for future research Author: STOUT, JANE CATHERINE Abstract: To inspire new ideas in research on pollination ecology, we list the most important unanswered questions in the field. This list was drawn up by contacting 170 scientists from different areas of pollination ecology and asking them to contribute their opinion on the greatest knowledge gaps that need to be addressed. Almost 40% of them took part in our email poll and we received more than 650 questions and comments, which we classified into different categories representing various aspects of pollination research. The original questions were merged and synthesised, and a final vote and ranking led to the resultant list. The categories cover plant sexual reproduction, pollen and stigma biology, abiotic pollination, evolution of animal-mediated pollination, interactions of pollinators and floral antagonists, pollinator behaviour, taxonomy, plant-pollinator assemblages, geographical trends in diversity, drivers of pollinator loss, ecosystem services, management of pollination, and conservation issues such as the implementation of pollinator conservation. We focused on questions that were of a broad scope rather than casespecific; thus, addressing some questions may not be feasible within single research projects but constitute a general guide for future directions. With this compilation we hope to raise awareness of pollination-related topics not only among researchers but also among non-specialists including policy makers, funding agencies and the public at large. Description: PUBLISHED

2011-01-01T00:00:00Z O'FLAHERTY, EOGHAN GRAY, NICHOLAS FREDERICK FRYER, MARTIN http://hdl.handle.net/2262/55415 2011-05-09T13:52:04Z 2011-01-01T00:00:00Z

Title: Evaluating the Measurement of Activated Sludge Foam Potential. Author: O'FLAHERTY, EOGHAN; GRAY, NICHOLAS FREDERICK; FRYER, MARTIN Abstract: The most widely used technique for assessing the propensity of activated sludge to suffer from biological foaming is to measure foam potential. This involves measuring the amount of foam produced from sludge under conditions of controlled aeration. Two approaches have been adopted: (1) Air is passed through specially designed columns from fine porous diffusers at a fixed rate to form uniform sized bubbles or (2) employing Alka-Seltzer™ tablets which effervesce when added to the sludge. Both tests generate foam formation which can then be quantified. Foam assessment in activated sludge is reviewed. A sintered disc aeration column was compared with the Alka-Seltzer™ test method and both methods examined under a range of different environmental conditions. Foam potential measured by the sintered disc method displayed better repeatability compared to the Alka-Seltzer test. The use of a wire cage placed over the tablets greatly improved the precision of the Alka-Seltzer test. A positive linear correlation was also found between foam potential and temperature (4–20 °C). Sludge solids concentration was also shown to influence foaming potential making comparisons between reactors problematic. Recommendations on how to improve the repeatability of foam potential measurements are given. Description: PUBLISHED

2011-01-01T00:00:00Z