This research examines the carbon budget implications of establishing miscanthus plantations as a bioenergy crop, highlighting its sustainability and the need for data on carbon cycling. Miscanthus, a C4 crop capable of high biomass production, may offer benefits but requires further modeling and quantification of carbon inputs and outputs. The study features ongoing experiments to track CO2 emissions and aims to refine carbon cycling models through collaboration with researchers in Aberdeen.

1. The carbon budget implications of
establishing Miscanthus plantations
Andy Robertson
(PhD candidate at CEH Lancaster)
Supervised by Dr. N. McNamara, Dr. C. Davies and Prof. P. Smith
with help from Dr. E. Bottoms, Dr. A. Stott and H. Grant

2. Problems and solutions
• National governments are committed to reducing CO2
emissions
• But as energy demands increase so too do CO2 emissions
from fossil fuel derived energy
• Renewable sources of energy are likely to be part of the
solution
• Bioenergy has great potential but uncertain just how
beneficial it can be - data is lacking!

3. Viability of bioenergy
• Sustainability criteria required before implementation
• Ecosystem services, carbon budgets, biodiversity...
• This research focuses on C budgets and C cycling
• Benefits are very location dependent but measuring
everywhere is impossible – therefore, modelling is required
• Several components of C cycling models are poorly
quantified and this research aims to ‘fill the gaps’

4. Miscanthus as a bioenergy crop
• Very different to other crops currently grown in the UK
• Miscanthus is a C4 crop species that can grow up to 4
meters tall and produce >10 t · ha-1 · yr-1
• Ideal life cycle for annual biomass production

5. Miscanthus life cycle
April
June August
March
December
October
February

6. Miscanthus as a bioenergy crop
• Each year a lot of litter is left on site after the plantation is
harvested. How much C does this add to the soil?

7. Carbon cycling in Miscanthus
• Carbon moves continuously through the ecosystem• Two C inputs to soil below a bioenergy crop – litter and
roots

8. Input manipulation experiment
• Trenches dug to exclude roots
• Plant litter managed monthly
• All plots sampled for:
Efflux of CO2
Soil C/N and NH4
+/NO3
- contents

9. Results to date – CO2 emissions
0
100
200
300
400
500
600
700
800
Single Litter Double Litter No Litter No Roots No Roots or Litter
CumulativeCO2emissions(mgCO2-C∙m-2)
Treatment

10. Miscanthus as a bioenergy crop
• Miscanthus C has a different isotopic signature to the soil
allowing belowground respiration to be partitioned
• This also allows the C from the plant to be traced into the
C in the soil
• Working with SIF upstairs to use 13CO2 values to track
how much CO2 is Miscanthus-derived.

11. Results to date – CO2 emissions
by source
0
100
200
300
400
500
600
700
Single Litter Double Litter No Litter No Roots No Roots or Litter
CumulativeCO2emissions(mgCO2-C∙m-2)
Treatment
C4 - Miscanthus Carbon
C3 - Original carbon

12. Future research
• Continued investigation and more detailed analysis of
current experiment
• Study the amount of Miscanthus C in soil from different
treatments
• Remove treatment effects on abiotic factors and
determine if differences in C efflux are still significant
• Going to Aberdeen in October to work with modellers
who can help apply the data to a C cycling model

13. Acknowledgements
Supervisors
Niall McNamara
(CEH Lancaster)
Pete Smith
(University of Aberdeen)
Christian Davies
(Shell Global Solutions)
Jon Finch
(CEH Wallingford)
Other acknowledgements
Emily Bottoms
Andy Stott
Helen Grant
Sean Case
Mike Whitfield
Simon Oakley
Harriet Rea
Photo credits to Emily Bottoms and
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