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Department of Biological and Medical Sciences
Faculty of Health and Life Sciences
I Joined Oxford Brookes in 1996. Prior to this, I was a lecturer in Aberdeen and a NERC Post-Doctoral Research Assistant at the then Queen Mary & Westfield College, London. My recent research focusses on the carbon dynamics of wetlands and their contribution to Global Warming.
In my role as Programme Lead for Biology and the Environment I am responsible for the curriculum development of several UG programmes including Environmental Sciences, Animal Biology & Conservation and Biology and PG MSc Conservation Ecology.
I am also the Programme Lead for several Collaborative Programmes including the Equine BScs and the FdScs in Equine Science & Management and Animal Behaviour & Welfare, and the Life Sciences Foundation year with Abingdon and Witney College and the FdSc and BSc top-ups in Animal Conservation, Applied Animal Management and Countryside Management with Bridgwater College.
I am Recruitment Lead for the Department of Biological & Medical Sciences and member of the Faculty Admissions and Recruitment Group.
I currently lead and teach on a double (30 CATs) Level 4 module in Biodiversity. My contribution relates to community and ecosystem ecology as well as ecological investigations and experimental design.
I teach on one Level 5 module on surveys and licensing where my contribution relates to habitat (Phase 1) and plant community (Phase 2) surveys and supporting students in relation to their taxonomic collection.
I lead and teach on two Level 6 modules. Environmental Change: field work and research (a double module, 30 CATs) which includes a field course to Devon. Within the module I lead on supporting students to develop a research strategy for their Reviews and on the writing of mock NERC grant proposals and organising and chairing the peer review Panels. I am module leader for the Environmental Consultancy in which students get a brief from an external client.
I lead an MSc module on Research Methods. My teaching on the module mainly focusses on introducing the dissertation, assessing student critiques of past dissertations and teaching on experimental design and data analysis, interpretation and presentation using Excel.
I contribute to other MSc modules including Ecology for conservation and Environmental Impact assessment mainly contributing lectures and practicals around habitat and community classification and Phase 1 and 2 survey methods.
In conclusion my main areas of expertise are around research methods, habitat and plant surveying and geochemical cycling and response to climate change.
I study the role of wetlands in carbon cycling. Throughout my work I have developed novel techniques for using quadruple mass spectrometry with a membrane inlet (QMS) to measure gaseous fluxes from and concentration profiles of dissolved gases in the field (predominantly peatlands but currently also small water bodies) or in collected cores. This technique allows real time in situ measurements at a low spatial resolution of many gases simultaneously (routinely CH4, CO2, O2, N2 and Ar). A clear understanding of carbon and greenhouse gas (GHG) fluxes these systems is of high importance to practitioners and policymakers in order for them to understand the current role of UK peatlands in climate change and improve management of peatlands for climate change mitigation.
Currently I am working on the carbon dynamics of small water bodies. They rapidly accumulate sediment, and therefore carbon and there is some evidence that, on a global scale, ponds may be sequestering as much carbon as the world’s oceans. However, the role of ponds in carbon cycling is unclear. The rate at which they return carbon as CO2 and CH4 requires quantification if their role in carbon cycling is to be understood. Ponds may differ in age, depth, temperature, oxygen concentration, nutrient inputs, water quality and litter types. There are therefore a number of factors which can influence decomposition processes and the amount of carbon stored or returned as CO2 or CH4. I am applying expertise gained from working on the carbon dynamics of bogs to small water bodies including the use of quadruple mass spectrometry in the field to get real time gaseous profiles.
Peat forming wetlands are globally important sources of the greenhouse gas CH(4). The variability of flux recordings from peatlands is however considerable and the distribution of CH(4) below the water table poorly described. Surface peat (0-500 mm below the water table) is responsible for the bulk of emissions and a localised region of intense CH(4) concentration may exist within this region but the structure of peat and presence of gas bubbles make the determination of in situ gas distributions problematic. We report on the in situ distribution and concentrations of CH(4), CO(2) and O(2) in surface bog peat cores using Quadrupole Mass Spectrometry and relate this to peat physical structure. Replicate cores collected in spring and autumn from both hollows and hummocks are used (n = 10). CH(4) recorded in almost every profile was localised in intense peaks reaching concentrations up to 350 mu M at depths where O(2) was absent. Each CH(4) peak had a coincident CO(2) peak with a minimum mean ratio of similar to 20:1 (CO(2):CH(4)) and we found more CH(4) beneath hollows than hummocks. In statistical comparisons CH(4) concentration and distribution differed significantly between profiles for each depth. We demonstrate that variability found within a single core is at least as great as that between cores collected across the bog. The distribution of CH(4) was negatively correlated with bulk density and in some cases the location of roots matched those of intense CH(4) concentration where bubbles had formed and been trapped. Our comparisons suggest variability in gas distribution is caused by a heterogenous peat structure that controls the movement of gas bubbles and contains localised hotspots of gas production. The small and fine root systems of vascular plants on the peatland surface may cause high levels of methanogenic activity in their vicinity and also represent a physical barrier capable of trapping CH(4) bubbles.
Cation availability in peat may limit CH(4) production and microbial activity and thereby impact on rates of organic matter accumulation and the chemical character of the peat. We quantify total, soluble, and exchangeable cation concentrations, Exchange Site Saturation Levels (ESSLs) and organic fractions in bog-peat profiles and compare these with fen peat. Total and soluble cation concentrations are not correlated and these and exchangeable cation concentrations are lower in bog than fen peat. In all sites these vary with depth and the distribution patterns of individual cations are unique. This is explained by variation in ESSL, which is negatively correlated with Cation Exchange Capacity (CEC). Total cation concentrations in bog peat are higher in the top and bottom fractions than in the middle. Soluble concentrations in surface bog peat are low, because cations are trapped due to low ESSL This does not occur in fen peat, with lower CEC and higher ESSL CEC is related to total organic matter content, not just to Sphagnum, which has been invoked as the explanatory variable of high CEC in peat bogs. There is a complexity in the mechanisms controlling cation availability in peat and we suggest that total, soluble and exchangeable cation fractions need to be taken into account in studies of cation limitation of microbial activity in organic soils. CEC may also chelate exo-enzymes, further inhibiting decay processes.
We examined the effect of cation treatments on methanogenic activity and nutrient release from exchange sites in raised bog and fen peats. Treatments consisted of cation chloride solutions (MgCl2, AlCl3 and PbCl2) applied individually. In raised bog peat Al3+ and Pb2+ increased CH4 production. Acorrelation was found between CH4 production and the amount of micro- and macronutrient cations released by the treatments. In calcareous fen peat, such a stimulation was also found, but there was no correlation between CH4 production and micro and macronutrient release. Direct nutrient and pH effects could not account for these observations. Thus the results support the hypothesis that the methanogenic community in the raised bog is limited by the availability of mineral nutrients and/or inactivity of exo-enzymes, both of which are bound onto exchange sites.
The quantification of greenhouse gas sources and sinks is important to understanding the impact of climate change. Methane (CH4) is a potent greenhouse gas, which, on a global scale, is released largely as a product of anaerobic microbial decomposition and predominantly from wetlands. A zone of intense CH4 production just below the water table is thought to contribute significantly to the overall flux from peat bogs. We describe the use of membrane inlet quadrupole mass spectrometry (QMS) to confirm the existence of bubbles, their gaseous concentrations and their localization at a fine spatial resolution within intact peat cores. We use the distribution of the noble gas argon (Ar) and the distinct QMS responses to dissolved and gaseous (bubble) phases to identify trapped bubbles with a resolution of 0.6 mm. Bubbles with CH4 concentrations of up to 20 kPa were widely distributed in the upper 300 mm of the cores with ˆ¼11% of all profiles comprising bubbles. The dissolved concentrations responsible for the bubbles were on average 83±80 Î¼m, indicating lower concentrations relative to other QMS studies. We suggest that if the distinction between dissolved and gaseous phases is not made in studies of CH4 within peat profiles then the prominence of bubbles is likely to result in overestimates of dissolved CH4 concentrations. Fluxes of CH4 from peat as a result of drawdown or other perturbation are likely to be large, rapid and short lived because of bubble burst, and also larger than from peat without bubbles. We suggest that the dynamics of fluxes need to be modelled taking into account both gaseous and dissolved phases. Estimates of potential fluxes that assume CH4 is dissolved are likely to overestimate fluxes if the gaseous phase has not been taken into account.
I organised a Thematic topic for the British Ecological Society meeting in 2006 on Wetland Restoration. Key questions addressed were whether current restoration management is working in terms of recolonisation and maintenance of flora, fauna and microbes, and functionality of physico-chemical, hydrological and ecosystem processes, and whether socioeconomic factors are fully integrated. The Key speaker was Curtis J. Richardson, Professor of Resource Ecology and Director of the Duke University Wetland Centre, North Carolina speaking on the ‘Restoration of the Mesopotamian marshes of Iraq’.