Improving the representation of large carbon pools in ecosystem models

Mat Williams (Edinburgh University)

John Grace (Edinburgh University)

Andreas Heinemeyer (York University)

Phil Ineson (York University)

Theresa MeachamGetty Images

Introduction:

Forests buffer the rate of atmospheric CO2 increase.

• Woody biomass carbon ~ 580 Mt.• Soil carbon stock (to 0.8M) ~1200 Mt.

• UK emissions 654Mt CO2 (2006).

• PhD scope: • Link soil scientists and plant biologists.• Link long time series measurements of

soil, canopy and forest growth.

www.noaa.gov

LULUCF (2006)

1. Features of forest large carbon pools

2. The uncertainties surrounding large carbon pools

3. The direction of my research.

Talk outline:

Oak Woodland: Getty Images

Forest carbon sequestration:

AtmospherePhotosynthesis

Root

Foliage

Wood

Fungi Soil

Fungal respiration

Plant respiration

Microbial respiration

Fast carbon fluxes:

View from flux tower: Harwood forest

Atmosphere-canopy interactions

Fast carbon fluxes:

Current photosynthesis drives soil respiration.

Hogberg, P., A. Nordgren, et al. (2001). "Large-scale forest girdling shows that current photosynthesis drives soil respiration." Nature 411(6839): 789-792.

Calculated fungal respiration

Calculated root respiration

Hogberg et al (2001)

Slow carbon fluxes:

Soil carbon fluxes

Arctopussy at Alice Holt

Woody Biomass

Getty Images

Uncertainties surrounding large carbon pools:

Below ground carbon fluxes are poorly understood.

Heinemeyer, A., I. P. Hartley, et al. (2007). "Forest soil CO2 flux: uncovering the contribution and environmental responses of ectomycorrhizas." Global Change Biology 13(8): 1786-1797.

Heinemeyer et al (2007)

Uncertainties surrounding large carbon pools:

Magnani, F., M. Mencuccini, et al. (2007). "The human footprint in the carbon cycle of temperate and boreal forests." Nature

CO2 fluxes change as a forest ages.

Magnani et al (2007)

1. Above ground processes influence below ground carbon pools.

Leaf fall

Bud burstBud burst

Soil CO2 efflux

(CO2 m-1 s-1)

March June Sep Dec March June

Adapted from Heinemeyer (2008)

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2

3

4

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The Direction of my research:

1. Above ground processes influence below ground carbon pools. Phenology measurements

MODIS Images:

Monks Wood, Cambridge. Courtesy of University of Southampton

Courtesy of Mat Disney, NERC, CTCD

Hemispherical photographs:

The Direction of my research:

2. Error within ecosystem models is lowest at mid-rotation

NEP

(t C ha-1 y-1)

Age (Years)

1. Disturbance recovery in young stands.

2. Patchy carbon allocation in old stands.

3. Root :Leaf Area change with age.

The Direction of my research:

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3. Root optimality theory should be incorporated within ecosystem models

Water Nutrients

CO2 Factors affecting the economics of carbon allocation:

•Stand age

•Competitive interactions

•Environmental factors

•Stand genetics

Leaves

Stems

Roots

The Direction of my research:

4. Use models to inform UK forest policy

Getty Images

Woodland policy aims in England:

• Ensure woodlands are resilient to impact of climate change.

• Protect and enhance environmental resources of soil, water and biodiversity.

• Improve competitiveness of woodland businesses, such as woodland products and reduction of carbon emissions.

‘A Strategy for England’s Trees, Woods and Forests’, Defra (2007)

The Direction of my research:

The Direction of my research:

Summary:

Large carbon pools sequester atmospheric carbon. Long time series data, modelling and earth observation techniques

may aid our understanding of processes. Model outputs can help make future predictions and inform policy.

Harwood Forest; Courtesy of Mat Disney, CTCD

Thank You

Any Questions?

The Direction of my research:

Griffin Forest

Wheldrake Forest

Alice Holt

•UK Field sites

•CarboAge project

•Michigan biological station

Harwood Forest