These slides were presented at the Early Career Researcher's Bioenergy Symposium held by the Centre for Ecology and Hydrology in Lancaster, UK at the end of March 2013. This talk by Andy Robertson presented his work regarding the influence of Miscanthus on soil carbon stocks and CO2 emissions resulting from the plantation's establishment.

1. Partitioning belowground CO2 emissions for a
Miscanthus plantation in Lincolnshire, UK
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
• The UK government aims to reduce CO2 emissions by 80% by
2050
• But energy demands are not projected to fall enough to offset the
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 grown in the UK but trials show it is
undemanding and productive
• Miscanthus is a deep-rooting C4 crop species that can grow up to 4
meters tall and produce >10 t · ha-1 · yr-1 aboveground
• Miscanthus C has a different isotopic signature to UK soil C
allowing changes to be quantified
• Measuring 13CO2 emitted and changes in soil 13C makes
Miscanthus ideal to study short term C cycling

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

6. Carbon inputs to soil – litter vs roots
• Each year over 2.5 tonnes of litter per hectare is left on
site after harvest. How much C does this add to the soil?

7. Root and litter manipulation experiment
• Roots extend down up to 4m
• Litter accumulates over time
• Plots set up in March 2009
• Sampled monthly at noon for 13CO2
from all treatments

8. 2.54
2.88
2.04
1.92
1.60
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Single Litter Double Litter No Litter No Roots No Roots or Litter
AnnualCO2emissions(tCO2-C∙ha-1)
Treatment
Annual CO2 effluxed from belowground
respiration
a, b a b, c c c
How much CO2 is lost through the influence of roots or litter annually?
Removing Miscanthus roots has a statistically significant impact on annual CO2 emissions

9. CO2 emissions over time
0
10
20
30
40
50
60
70
80
Respirationrate(mgCO2-C∙m-2∙hr-1)
Single Litter
No Roots or Litter
How do belowground CO2 emissions vary throughout the year?
CO2 emissions peak during summer months when the crop is growing and the soil is warmer

10. Seasonal CO2 emissions
1.11
4.88
4.94
-7.41 -6.58
-5.48
-6.38
-13.85
-1.53
-6.88
-19.26
-7.60
-25
-20
-15
-10
-5
0
5
10
Mar-Jun Jul-Oct Nov-Feb
Respirationrate(mgCO2-Cm-2hr-1)
Double Litter No Litter No Roots No Roots or Litter
How do C emissions vary seasonally? Does the influence of litter or roots vary?
The presence of roots is statistically significant during summer and litter during winter
*
*
*
*

11. CO2 emissions by source
How much of the C emissions are from Miscanthus sources?
Each year the presence of roots alone creates more C emissions than the presence of litter alone
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Single Litter Double Litter No Litter No Roots No Roots or Litter
AnnualCO2emissions(tCO2-C∙ha-1)
Treatment
Pre-experiment C4 influence
C4 - Miscanthus Carbon
C3 - Original carbon

12. Future research
• Further statistical analysis on gas fluxes and remove treatment
effects on abiotic factors
• Study the amount of Miscanthus C in soil from different treatments
• Working with modellers in Aberdeen and Colorado to apply the
data to C cycling models
• Estimate the longevity of Miscanthus-derived soil C by use of
physio-chemical fractionation

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