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Estimating litter carbon stocks on forest land in the United States

Formally Refereed

Abstract

Forest ecosystems are the largest terrestrial carbon sink on earth, withmore than half of their net primary productionmoving to the soil via the decomposition of litter biomass. Therefore, changes in the litter carbon (C) pool have important implications for global carbon budgets and carbon emissions reduction targets and negotiations. Litter accounts for an estimated 5% of all forest ecosystem carbon stocks worldwide. Given the cost and time required to measure litter attributes, many of the signatory nations to the United Nations Framework Convention on Climate Change report estimates of litter carbon stocks and stock changes using default values from the Intergovernmental Panel on Climate Change or country-specificmodels. In the United States, the country-specificmodel used to predict litter C stocks is sensitive to attributes on each plot in the national forest inventory, but these predictions are not associated with the litter samples collected over the last decade in the national forest inventory. Here we present, for the first time, estimates of litter carbon obtained using more than 5000 fieldmeasurements from the national forest inventory of the United States. The field-based estimates mark a 44% reduction (2081±77 Tg) in litter carbon stocks nationally when compared to country-specific model predictions reported in previous United Framework Convention on Climate Change submissions. Our work suggests that Intergovernmental Panel on Climate Change defaults and country-specificmodels used to estimate litter carbon in temperate forest ecosystemsmay grossly overestimate the contribution of this pool in national carbon budgets.

Keywords

United Framework Convention on Climate Change, Greenhouse gas, National forest inventory, Forest floor, Carbon budget

Citation

Domke, Grant M.; Perry, Charles H.; Walters, Brian F.; Woodall, Christopher W.; Russell, Matthew B.; Smith, James E. 2016. Estimating litter carbon stocks on forest land in the United States. Science of The Total Environment. 557-558: 469-478.
Citations
https://www.fs.usda.gov/research/treesearch/52186