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Title: Emission of greenhouse gases from forest soils : measured and modelled
Author: Cade, Shirley M.
ISNI:       0000 0004 8499 4291
Awarding Body: Royal Holloway, University of London
Current Institution: Royal Holloway, University of London
Date of Award: 2017
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Forests and their soils are important for the mitigation of greenhouse gas emissions (GHG) but can become net sources of GHGs following management or environmental change. Their response to multiple changes is best studied by process-based models. This study evaluates the model, LandscapeDNDC for simulating soil CO2, N2O and NO fluxes and ecosystem CO2 fluxes from an oak forest in SE England and a spruce forest in central Scotland. LandscapeDNDC consists of several sub-modules, including two forest physiology options, PnET and PSIM. In the oak forest, where a significant understorey contributes to the ecosystem respiration and productivity, simulations from PnET and PSIM were compared. Statistical evaluation showed that PSIM produced results closer to measurements helped by the fact that it differentiates between competing requirements of understorey and canopy trees. LandscapeDNDC simulated annual N2O and NO soil emissions at the same order of magnitude as measurements but with less variability. The spruce forest is a relatively young plantation on ploughed heathland with no understorey and therefore only PnET was evaluated. With modifications to parameters and tree shape, LandscapeDNDC simulated measured ecosystem CO2 fluxes well, but overestimated soil CO2 and to a lesser extent N2O. Soil chamber measurements of CO2, CH4, N2O and NO were made for this study at the oak forest over 16 months to provide data to compare with simulations. This showed seasonal variations and relationships with soil moisture and temperature consistent with previous measurements at the site for CO2, CH4 and N2O. NO had not previously been measured here and only trace quantities were detected. Addition of N fertiliser to plots in the oak forest showed increased N2O and NO fluxes as pulses of a few days duration and confirmed the technique for NO flux measurement. Soil chambers employed here took part in the international N2O chamber intercomparison. Peliminary results suggest they perform well compared to other designs.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: greenhouse gas ; FOREST SOILS ; Modelling and Simulation ; oak forest ; spruce forest ; N2O flux ; CO2 flux ; NO flux ; LandscapeDNDC ; soil chamber ; forest ecosystem