Agroforestry systems for ammonia abatement

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Agroforestry systems for ammonia abatement
National benefits of ammonia recapture by trees
Mark Theobald
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Locally - Four-way benefit of trees
3. Increased mixing of the air
Direction of Wind
2. Recapture of NH3 by trees
-30
-10
1. Sheltering Reduces Emissions
-20
Ammonia sources
4. Recapture of NH3 from livestock under trees
-80 (?)
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What could be the effect nationally of extra
trees?
Additional tree planting could enhance local
recapture and dispersion and provide a benefit
nationally by reducing N deposition to sensitive
habitats.
Modelled UK NH3 dry deposition
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Scenario modelling

• Scenario 50 more tree cover
• (extreme case but is for illustration)
• NH3 dry deposition increases in the UK due to
  recapture by the additional trees
• However, this increased deposition is to the
  additional sink woodland, meaning that
  deposition to sensitive habitats is reduced
• Deposition to existing woodland Decreases by
  10
• Deposition to moorland
• Decreases by 6

Modelled change in NH3 dry deposition
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Reductions in deposition and concentrations
Modelled reduction in NH3 dry deposition to
moorland
Modelled reduction in NH3 concentrations
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Next steps

• These are preliminary results from a 3 year
  project
• This work will be expanded to include specific
  abatement factors for woodland planted close to
  NH3 sources
• These factors will take into account the 4-way
  benefit of trees presented earlier using data
  from field measurements and process modelling

Acknowledgements We are grateful for the
financial support from the Department for the
Environment, Food and Rural Affairs (DEFRA
Project No. AC0201).