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| Titel |
Partitioning belowground CO2 emissions for a Miscanthus plantation in Lincolnshire, UK |
| VerfasserIn |
Andrew Robertson, Pete Smith, Christian Davies, Emily Bottoms, Niall McNamara |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250073319
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| Zusammenfassung |
| Miscanthus is a lignocellulosic crop that uses the Hatch-Slack (C4) photosynthetic pathway
as opposed to most C3 vegetation native to the UK. Miscanthus can be grown for a number of
practical end-uses but recently interest has increased in its viability as a bioenergy
crop; both providing a renewable source of energy and helping to limit climate
change by reducing carbon (C) emissions associated with energy generation. Recent
studies have shown that Miscanthus plantations may increase stocks of soil organic
carbon (SOC), however full greenhouse gas (GHG) budgets must be calculated.
Consequently, we monitored emissions of N2O, CH4 and CO2 from Miscanthus roots,
decomposing plant litter and soil individually to quantify and partition these emissions and
better understand the influence of abiotic factors on SOC and GHG dynamics under
Miscanthus.
In January 2009 twenty-five 2 m2 plots were set up in a three-year old 11 hectare
Miscanthus plantation in Lincolnshire, UK; with five replicates of five treatments. These
treatments varied plant input to the soil by way of controlled exclusion techniques.
Treatments excluded roots only (“No Roots”), surface litter only (“No Litter”), both roots and
surface litter (”No Roots or Litter”) or had double the litter amount added to the soil surface
(“Double Litter”). A fifth treatment was a control with undisturbed roots and an average
amount of litter added. Monthly measurements of CO2, CH4 and N2O emissions were taken
at the soil surface from each treatment between March 2009 and March 2013, and soil C from
the top 30 cm was monitored in all plots over the same period. Miscanthus-derived SOC was
determined using the isotopic discrimination between C4 plant matter and C3 soil, and the
treatments were compared to assess their effects on C inputs and outputs to the
soil.
Both CH4 and N2O emissions were below detection limits, mainly due to a lack of
fertiliser additions and limited management of the agricultural site. However, ongoing results
for CO2 emissions indicate a strong seasonal variation; litter decomposition forms a large
portion of the CO2 emissions in winter and spring whereas root respiration dominates the
summer and autumn fluxes. Results to date indicate that the “No Roots or Litter” and “No
Litter” treatments have significantly less Miscanthus-derived C, and therefore significantly
less CO2 emitted from decomposing ’new’ C.
We hypothesised that the high C input treatments would stimulate large outputs but also
increase soil C stocks. However, whilst CO2 efflux varies significantly between treatments,
results from the first two years of the experiment do not suggest that any increase in SOC
is significant. Four years of continuous monitoring, chemical and physical soil
fractionation and ecosystem C cycle modelling will allow a more comprehensive
analysis to partition belowground trace gas efflux by plant input and over time. |
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