Carbon fractions in the world’s dead wood

Adam Martin, Grant M. Domke, Mahendra Doraisami, Sean C. Thomas

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Received Date: 15th May 20

Alarming increases in tree mortality due to environmental change suggest that contributions of dead wood to global carbon (C) cycles are rapidly increasing, with dead wood C flux estimates already approximating total annual anthropogenic C emissions. Quantifying C in dead wood critically depends on accurate estimates of dead wood C fractions (CFs) to convert dead woody biomass into C. Most C accounting protocols, including those recently revised by the IPCC 5, utilize a default dead wood CF of 50%, but live tree studies suggest this assumption results in substantial bias in forest C estimates. Here we compile and analyze a global database of dead wood CFs in trees, showing that dead wood CFs average 48.5% across forests worldwide, deviating significantly from 50%, with systematic variation among biomes, phylogenetic groups, tissue types, and decay classes. Accounting for data-driven dead wood CFs corrects systematic overestimates in global dead wood C stock estimates of ~1.6 Pg C, an estimate approaching annual C flux estimates from land-use change globally. Our analysis provides, for the first time, robust empirical CFs for dead wood globally to inform global terrestrial C accounting protocols, and revise estimates of forest C stocks and fluxes.

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This is an abstract of a preprint hosted on an independent third party site. It has not been peer reviewed but is currently under consideration at Nature Communications.

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