Skip to main content
U.S. flag

An official website of the United States government

Constrained partitioning of autotrophic and heterotrophic respiration reduces model uncertainties of forest ecosystem carbon fluxes but not stocks

Author(s):

Mariah S. Carbone
Andrew D. Richardson
Min Chen
Eric A. Davidson
Holly Hughes
Kathleen E. Savage

Year:

2016

Publication type:

Scientific Journal (JRNL)

Primary Station(s):

Northern Research Station

Source:

Journal of Geophysical Research: Biogeosciences

Description

We partitioned the soil carbon dioxide flux (Rs) into its respective autotrophic and heterotrophic components in a mature temperate-boreal forest (Howland Forest in Maine, USA). We combined automated chamber measurements of Rs with two different partitioning methods: (1) a classic root trenching experiment and (2) a radiocarbon (14C) mass balance approach. With a model-data fusion approach, we used these data to constrain a parsimonious ecosystem model (FöBAAR), and we investigated differences in modeled C fluxes and pools under both current and future climate scenarios. The trenching experiment indicated that heterotrophic respiration accounted for 53 ± 11% of total Rs. In comparison, using the 14C method, the heterotrophic contribution was 42 ± 9%. For both current and future model runs, incorporating the partitioning data as constraints substantially reduced the uncertainties of autotrophic and heterotrophic respiration fluxes. Moreover, with best fit model parameters, the two partitioning methods yielded fundamentally different estimates of the relative contributions of autotrophic and heterotrophic respiration to total Rs, especially at the annual time scale. Surprisingly, however, modeled soil C and biomass C pool size trajectories did not differ significantly between model runs based on the different methods. Instead, model differences in partitioning were compensated for by changes in C allocation, resulting in similar, but still highly uncertain, soil C pool trajectories. Our findings show that incorporating constraints on the partitioning of Rs can reduce model uncertainties of fluxes but not pools, and the results are sensitive to the partitioning method used.

Citation

Carbone, Mariah S.; Richardson, Andrew D.; Chen, Min; Davidson, Eric A.; Hughes, Holly; Savage, Kathleen E.; Hollinger, David Y. 2016. Constrained partitioning of autotrophic and heterotrophic respiration reduces model uncertainties of forest ecosystem carbon fluxes but not stocks. Journal of Geophysical Research: Biogeosciences. 121(9): 2476-2492. https://doi.org/10.1002/2016JG003386.

Cited

Publication Notes

  • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
  • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
https://www.fs.usda.gov/treesearch/pubs/56992