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Miscanthus trace gases - EGU13

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  1. 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. 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. 3. Viability of bioenergy Sustainability criteria required before implementation Ecosystem services, carbon budgets, biodiversity... This research focuses on C budgets and C cycling Changes 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. 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 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. 5. Miscanthus life cycle April June August March December October February
  6. 6. Carbon inputs to soil litter vs roots Each year >2.5 tonnes litter per hectare is still on site after harvest Belowground biomass can be >15 tonnes per hectare How much C do these add to the soil individually?
  7. 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. 8. 25.74 28.47 20.92 18.02 15.91 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 Single Litter Double Litter No Litter No Roots No Roots or Litter Respirationrate(mgCO2-Cm-2hr-1) CO2 effluxed from belowground respiration a a b b,c c How much CO2 is lost through the influence of roots or litter? Removing Miscanthus roots and/or litter significantly reduces average CO2 emissions
  9. 9. CO2 emissions over time 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 0 10 20 30 40 50 60 Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Respirationrate(mgCO2-Cm-2hr-1) Single Litter
  10. 10. Difference in CO2 emissions from control How do the treatments affect respiration throughout the year? CO2 is decreased considerably when roots and/or litter are removed, particularly from May-Nov -25 -20 -15 -10 -5 0 5 10 Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb DifferenceinrespirationratefromSingle Littertreatment(mgCO2-Cm-2hr-1) Double Litter No Litter No Roots No Roots or Litter
  11. 11. Seasonal CO2 emissions difference from control 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 DifferenceinrespirationratefromSingle Littertreatment(mgCO2-Cm-2hr-1) Double Litter No Litter No Roots No Roots or Litter How do CO2 emissions vary seasonally? Does the influence of litter or roots vary? The presence of roots is statistically significant during summer and litter during winter * * * *
  12. 12. Average respiration by source C3 vs C4 How much of the CO2 emissions can be attributed to new Miscanthus inputs? More CO2 comes from C3 and pre-experiment C4 sources than from new root and litter inputs 5.10 4.83 6.61 5.99 7.19 11.92 14.93 5.60 3.31 0 5 10 15 20 25 30 Single Litter Double Litter No Litter No Roots No Roots or Litter Respirationrate(mgCO2-Cm-2hr-1) Pre-experiment C4 influence C4 - Miscanthus carbon C3 - Original soil carbon
  13. 13. 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 Determine where changes in soil C are lost from or added to by use of physio-chemical fractionation
  14. 14. Conclusions Roots account for 30% of CO2 and aboveground plant litter accounts for 19% Between year 4 and year 8 less than 50% of CO2 emitted came from fresh C inputs No roots only significantly decreases CO2 emissions from Jul-Oct and no plant litter only significantly decreases emissions Nov-Feb With information regarding the destination of new soil C sequestered the longevity of any increased soil C can be attained
  15. 15. 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 Jon Finch Johnathan Wright Colleagues at CEH Lancaster Photo credits to Emily Bottoms and www.SimplyNetworking.com

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