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| Titel |
Land use change to Miscanthus: measured and modelled changes in soil carbon fractions |
| VerfasserIn |
Andy Robertson, Christian Davies, Pete Smith, Niall McNamara |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250086588
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| Publikation (Nr.) |
 EGU/EGU2014-482.pdf |
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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 improving the
carbon (C) budgets associated with energy generation. Miscanthus distribution is very limited
at present and therefore in most cases propagation will require land use change.
Limited case studies have shown that changing land use to Miscanthus may increase
stocks of soil organic carbon (SOC). However, the accuracy of simulating SOC
dynamics under Miscanthus for scaling purposes is limited by empirical validation data
regarding the longevity of newly sequestered SOC1. Consequently, in our work the
size and turnover times of different SOC fractions have been quantified through
physiochemical fractionation2 under a Miscanthus plantation and an adjacent paired
reference site.
Twenty-five 2 m2 plots were set up in a three-year old 11 hectare commercial Miscanthus
plantation in Lincolnshire, UK. From each plot monthly measurements of CO2 emissions
were taken at the soil surface 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
and CO2 emissions resulting from Miscanthus plant matter were determined using
the isotopic discrimination between C4 plant matter and C3 soil. Stable isotope
techniques were also used in conjunction with soil fractionation performed annually to
establish the rate of change to different soil fractions. Soil C and fractionation was also
performed on five soils from an adjacent site with continued cropping of the prior land
use.
There is a notable increase in SOC stocks under Miscanthus when compared with the
adjacent reference site (2.05 tC ha-1 yr-1) despite fractionation indicating the
Miscanthus-derived SOC has fairly short mean residence times within the different fractions.
Particulate organic matter and dissolved organic carbon fractions have the fastest turnover
times whereas the fraction containing sand and aggregates has the slowest turnover time.
Early results indicate that the majority of new Miscanthus-derived C is added to the
non-resistant silt and clay fraction although the size of this fraction’s C pool does not increase
significantly. Using the data collected, the DayCent3 and ECOSSE4 models will be
developed to improve predictions so uncertainties are reduced regarding how quickly
SOC stocks beneath a newly established Miscanthus plantation can be expected to
change.
References
1 – Robertson et al., 2013. Modelling the carbon cycle of Miscanthus plantations: existing
models and the potential for their improvement. GCB Bioenergy. doi: 10.1111/gcbb.12144.
2 – Zimmermann et al., 2007. Measured soil organic matter fractions can be related to
pools in the RothC model. European Journal of Soil Science, 58:658–667.
3 - Parton et al., 1998. DAYCENT and its land surface submodel: description and testing.
Global Planet Change, 19:35–48.
4 - Smith et al., 2010. Estimating changes in Scottish soil carbon stocks using
ECOSSE. I. Model description and uncertainties. Climate Research, 45:179–192. |
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