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Title: Microbial dynamics in High-Arctic proglacial soils : an integrated modelling, field and laboratory approach
Author: Bradley, James A.
ISNI:       0000 0004 6059 7101
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2016
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Polar regions have recently been subject to warming at almost double the global average, causing the retreat of glacier and ice cover and exposing large expanses of terrestrial habitats. These pioneer ecosystems are colonised by microbes. Microbial activity is thought to be responsible for the initial build-up of biomass, organic carbon and nutrients, facilitating the growth of higher order plants in developed soils. However, the reliance of the microbial community on ancient carbon pools, external sources (e.g. deposition) of nutrients, photosynthesis and nitrogen fixation is unknown. Furthermore, the seasonal dynamics are largely unexplored. Thus, SHIMMER (Soil biogeocHemIcal Model for Microbial Ecosystem Response) was developed. SHIMMER is a new numerical modelling framework designed to simulate pioneer ecosystem dynamics in glacier forefields. Initial performance and sensitivity tests showed model dynamics are highly dependent on microbial growth and death rate constants, growth efficiency, and 010 values. The model was applied to the Midtre Lovembreen forefield (Svalbard) and key model parameters were refined based on laboratory measurements. Model output and field data showed that in situ bacterial production is responsible for the observed accumulation of biomass and nutrients over several decades. Carbon fluxes were also shown to increase with soil age. Additionally, modelling showed that microbial dynamics in Arctic soils are susceptible to future anthropogenically-induced climate changes. Aspects of these glacier forefield systems that require further empirical research are: entire catchment nutrient budgets (in particular estimating allochthonous deposition), increasing data availability (especially during the winter), and improving mathematical formulation of biological processes (e.g. cell death rates and nitrogen fixation). SHIMMER is a new quantitative and process-focussed approach that improves the general understanding of glacier forefield soils, and the significance of glacier forefield soils in local to global scale biogeochemical cycles.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available