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| Titel |
Investigating the GHG Implications of Establishing Biomass Crops: an Ecosystem-Scale Study |
| VerfasserIn |
Órlaith Ní Choncubhair, Dominika Krol, Bruce A. Osborne, Michael B. Jones, Michael L. Williams, Gary J. Lanigan |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250053091
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| Zusammenfassung |
| Current EU proposals set ambitious environmental targets for the year 2020, including a
20-30% EU-wide reduction in greenhouse gas (GHG) emissions relative to 2005 levels and
an increase to 20% in the share of renewable energy in final energy consumption. Land-use
change to biomass crop production can aid in the mitigation of GHG emissions by displacing
fossil fuels and enhancing removals or ‘sinks’ of carbon in vegetative pools and soil carbon
reservoirs. However, if the maximum mitigation potential is to be realised, the impact of land
conversion to biomass crop cultivation on terrestrial carbon and nitrogen cycle dynamics
needs to be better quantified.
The GHG balance implications of establishing biomass crops at an ecosystem scale were
assessed using field-scale plots of Miscanthus à giganteus and Reed Canary Grass (Phalaris
arundinacea) established on land previously under permanent pasture in the south-east of
Ireland. Post-ploughing CO2 emissions, measured using the chamber method, were
found to be high but transitory, with fluxes returning to levels close to background
within a matter of hours. Subsequent N2O emissions were observed to be 30%
higher on the Miscanthus sites than on the Reed Canary Grass plots, most likely
due to a lower N use by the sward arising from slower establishment. The carbon
balance between the two major determinants of the ecosystem carbon budget, gross
primary productivity (GPP) and total ecosystem respiration (Reco), was assessed
using the eddy covariance technique. Measured cumulative fluxes from Miscanthus
and Reed Canary Grass reflected major disparities in canopy structure and crop
development in the early establishment phase. Reed Canary Grass in its first year of
establishment demonstrated higher rates of carbon uptake than Miscanthus in its second
year of growth. This difference was largely a consequence of significantly greater
leaf cover in the Reed Canary Grass plot, giving rise to higher light interception
and photosynthetic rates at an ecosystem scale. However, the superior carbon sink
strength shown by Reed Canary Grass in the early establishment period may not
persist once Miscanthus reaches crop maturity and its higher productivity levels. |
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