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| Biomass above ground
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| Definition |
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The amount of living substance in a defined sample.
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| Rationale |
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Biomass is a key variable in annual and long-term changes in the global terrestrial carbon cycle, and in modelling carbon uptake and redistribution within the ecosystem. Of most interest is the live woody biomass. It mediates and buffers atmospheric carbon concentrations and thus its dynamics must be understood if annual spatial variations in atmospheric CO2 are to be related to spatial weather variables. It is also a key variable (along with carbon emissions and carbon sequestration rates) in defining carbon status and flux in a given geopolitical unit for assessment of carbon taxes, and similar international atmospheric CO2 mitigation measures.
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| Users |
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Ecosystem and carbon modellers, decision-makers concerned with international measures to mitigate atmospheric carbon increases.
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| Assessment method |
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Tiers 1-3: destructive sampling, allometric equations;
Tier 5: inferred from spectral radiance measurements (non-woody types, experimental stage).
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| Units of Measure |
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g/m2.
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| Frequency of measurement |
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Once every 5 years.
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| Spatial resolution |
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0.01 to 1 km2 .
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| Accuracy/precision required |
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± 10%.
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| Associated measurements |
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Below-ground biomass, NEP, necromass, vegetation structure, vegetation roughness.
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| Present status |
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Data available are very coarse-grained in developed countries, almost non-existent in less-developed countries; resulting estimates vary widely.
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| R and D needed |
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Research is required to determine the feasibility of estimating live biomass from satellite data; radar measurements presently offer the best prospect. Imaging laser sensor technology is also promising but no space-borne missions are planned.
Currently, biomass is determined from labour-intensive techniques involving sampling, drying and weighing all vegetation on a given unit area, including whole tree and root system harvesting. Beyond these techniques, it is uncertain how we can more efficiently get biomass data for the modelling efforts within the next 5 years;
Encourage R and D on biomass estimation from now highly-experimental satellite techniques.
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