Use this URL to cite or link to this record in EThOS:
Title: Impact of nitrogen deposition on methane and ammonia oxidising microbial communities in forest soils
Author: Thorpe, E. L.
ISNI:       0000 0004 2722 6210
Awarding Body: University of Essex
Current Institution: University of Essex
Date of Award: 2012
Availability of Full Text:
Access from EThOS:
Nitrogen saturation through elevated nitrogen deposition may occur in many broadleaved and coniferous forests in the UK. This thesis addresses the potential impacts of such depostion by analysing the community structure and potential activity rates of two important functional microbial groups- the ammonia oxidising bacteria and archaea (AOB/AOA) and the methane oxidising bacteria (MOB)- in forest soils subject to high and low levels of nitrogen deposition (Hockham Heath and Alice Holt respectively). Nitrification is a key process in the global cycling of nitrogen, converting ammonia into nitrate via nitrite. Excess ammonium as a result of nitrogen deposition may lead to the production of nitrate, which is soluble and susceptible to leaching, potentially leading to pollution of surface- and groundwaters. Analysis of the communitiy structure of AOB and AaA by 16S rRNA and amoA genes was undertaken, and revealed presence of these organisms in the majority of soils sampled. The NPR (nitrification potential rates) of these communities was dependent on both the level of nitrogen deposition and the predominant tree species. In comparison to non nitrogen-impacted sites, there was a reduction in NPR of soils subject to high levels of nitrogen for Corsican pine plots, whilst for Beech plots, NPR increased. This is particularly important in forest management strategies and has contributed to knowledge of optimum tree species to plant depending upon the proximity to nitrogen sources. Previous studies have indicated that high concentrations of ammonium and nitrate may inhibit methane oxidation by MOB. In these forest soils, there was no correlation between soil nitrogen concentration and methane oxidation potential. The pmoA genes from MOB were detected in only few soils at Hockham Heath and the majority of soils at Alice Holt. This indicates that MOB communities and activity rates were not affected directly by ammonium or nitrate, but may instead have been influenced by other soil variables.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available