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Measuring and modelling above-ground carbon and tree allometry along a tropical elevation gradient

Measuring and modelling above-ground carbon and tree allometry along a tropical elevation gradient
Measuring and modelling above-ground carbon and tree allometry along a tropical elevation gradient
Emerging international policy aimed at reducing carbon emissions from deforestation and forest degradation (REDD+) in developing countries, has resulted in numerous studies on above-ground live carbon (AGC) in tropical forests. However, few studies have addressed the relative importance of disturbance, topography, climate, soil and methods for stem measurement, on the estimation of AGC, or the costs of improving AGC estimates by altering sample regimes. We established 18 one hectare plots containing 7201 stems, stratified along forested elevationgradients in Tanzania. We recorded a broad set of physical, climatic and edaphic predictors of AGC and tree stature. AGC estimates using stem diameter, height and wood density, gave a mean value of 174.6 t ha?1, compared with 229.6 t ha?1 when height was excluded. Regression models revealed that stems were tallest for a given diameter at mid-elevation (1000–1250 m), on south-facing slopes, and without past logging. High AGC was strongly associated with shallow slopes, followed by intermediate elevation, elephant absence, low potential evapotranspiration and low soil pH. Further regression models to investigate the structural habitat features associated with AGC, revealed significant positive influence of basal area, stem density, and height:diameter ratio, rather than the mean wood density of species present. Large stems (?70 cm dbh; 4.6% of stems) contained 52% of AGC in all plots, declining to 36% in lowland plots. We discuss the cost:benefit of different measurements and recommend a tiered approach to AGC monitoring, depending on available resources. AGC assessments in African forests could exclude small stems, but should aim to record disturbance, topography and species. Stem height is vital for AGC estimation and valuation; when excluding height our 55 t ha?1 over-estimation of AGC would have over-valued the carbon resource by 24% (US$3300 ha?1)
0006-3207
20-33
Marshall, A.R.
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Willcock, S.
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Platts, P.J.
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Lovett, J.C.
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Balmford, A.
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Burgess, N.D.
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Latham, J.E.
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Munishi, P.K.T.
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Salter, R.
c40d9165-5fed-47ab-a323-b576cf726fa3
Shirima, D.D.
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Lewis, S.L.
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Marshall, A.R.
0b018ca5-76e5-48d2-abd5-5c741dae6e41
Willcock, S.
89d9767e-8076-4b21-be9d-a964f5cc85d7
Platts, P.J.
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Lovett, J.C.
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Balmford, A.
f60edef7-9dd0-4197-ae4b-8e8dbf3a04c1
Burgess, N.D.
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Latham, J.E.
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Munishi, P.K.T.
d3454293-a771-4431-ba01-c5581195753e
Salter, R.
c40d9165-5fed-47ab-a323-b576cf726fa3
Shirima, D.D.
1725f6ec-c890-486c-b0f0-614965b78378
Lewis, S.L.
70048d3b-f6e0-4292-b08f-8eab49be2c43

Marshall, A.R., Willcock, S., Platts, P.J., Lovett, J.C., Balmford, A., Burgess, N.D., Latham, J.E., Munishi, P.K.T., Salter, R., Shirima, D.D. and Lewis, S.L. (2012) Measuring and modelling above-ground carbon and tree allometry along a tropical elevation gradient. Biological Conservation, 154, 20-33. (doi:10.1016/j.biocon.2012.03.017).

Record type: Article

Abstract

Emerging international policy aimed at reducing carbon emissions from deforestation and forest degradation (REDD+) in developing countries, has resulted in numerous studies on above-ground live carbon (AGC) in tropical forests. However, few studies have addressed the relative importance of disturbance, topography, climate, soil and methods for stem measurement, on the estimation of AGC, or the costs of improving AGC estimates by altering sample regimes. We established 18 one hectare plots containing 7201 stems, stratified along forested elevationgradients in Tanzania. We recorded a broad set of physical, climatic and edaphic predictors of AGC and tree stature. AGC estimates using stem diameter, height and wood density, gave a mean value of 174.6 t ha?1, compared with 229.6 t ha?1 when height was excluded. Regression models revealed that stems were tallest for a given diameter at mid-elevation (1000–1250 m), on south-facing slopes, and without past logging. High AGC was strongly associated with shallow slopes, followed by intermediate elevation, elephant absence, low potential evapotranspiration and low soil pH. Further regression models to investigate the structural habitat features associated with AGC, revealed significant positive influence of basal area, stem density, and height:diameter ratio, rather than the mean wood density of species present. Large stems (?70 cm dbh; 4.6% of stems) contained 52% of AGC in all plots, declining to 36% in lowland plots. We discuss the cost:benefit of different measurements and recommend a tiered approach to AGC monitoring, depending on available resources. AGC assessments in African forests could exclude small stems, but should aim to record disturbance, topography and species. Stem height is vital for AGC estimation and valuation; when excluding height our 55 t ha?1 over-estimation of AGC would have over-valued the carbon resource by 24% (US$3300 ha?1)

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Published date: October 2012
Organisations: Environmental

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Local EPrints ID: 342529
URI: http://eprints.soton.ac.uk/id/eprint/342529
ISSN: 0006-3207
PURE UUID: fdabf5f6-0c21-4c0d-85fe-68a747595a74

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Date deposited: 05 Sep 2012 12:26
Last modified: 14 Mar 2024 11:53

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Contributors

Author: A.R. Marshall
Author: S. Willcock
Author: P.J. Platts
Author: J.C. Lovett
Author: A. Balmford
Author: N.D. Burgess
Author: J.E. Latham
Author: P.K.T. Munishi
Author: R. Salter
Author: D.D. Shirima
Author: S.L. Lewis

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