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Title: Partitioning CO2 fluxes with isotopologue measurements and modeling to understand mechanisms of forest carbon sequestration

1. Project Summary and Objectives This project combines automated in situ observations of the isotopologues of CO2 with root observations, novel experimental manipulations of belowground processes, and isotope-enabled ecosystem modeling to investigate mechanisms of below- vs. aboveground carbon sequestration at the Harvard Forest Environmental Measurements Site (EMS). The proposed objectives, which have now been largely accomplished, include: A. Partitioning of net ecosystem CO2 exchange (NEE) into photosynthesis and respiration using long-term continuous observations of the isotopic composition of NEE, and analysis of their dynamics ; B. Investigation of the influence of vegetation phenology on the timing and magnitude of carbon allocated belowground using measurements of root growth and indices of belowground autotrophic vs. heterotrophic respiration (via trenched plots and isotope measurements); C. Testing whether plant allocation of carbon belowground stimulates the microbial decomposition of soil organic matter, using in situ rhizosphere simulation experiments wherein realistic quantities of artificial isotopically-labeled exudates are released into the soil; and D. Synthesis and interpretation of the above data using the Ecosystem Demography Model 2 (ED2).
 [1] ;  [2] ;  [1] ;  [3] ;  [4] ;  [2]
  1. Woods Hole Research Center, Falmouth, MA (United States)
  2. Univ. of Arizona, Tucson, AZ (United States)
  3. Boston Univ., MA (United States)
  4. Harvard Univ., Cambridge, MA (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
DOE Contract Number:
Resource Type:
Technical Report
Resource Relation:
Related Information: Published: Abramoff, RZ, Finzi AC. 2015. Are above‐and belowgroundphenology in sync? New Phytologist, 205:10541061.Drake JE, Darby BA, Giasson MA, Kramer MA, Phillips RP, Finzi AC. 2013.Stoichiometry constrains microbial responses to root exudation:insights from a model and experiment in a temperate forest.Biogeosciences 10:821838.Finzi AF, Abramoff RZ, Darby BA, Spiller KS, Brzostek ER, Phillips RP. 2014. Rhizosphere processes are quantitatively important components of terrestrial carbon and nutrient cycles. Global Change Biology. 21:20822094.Wehr R and S. R. Saleska (2015). An improved isotopic method for partitioning net ecosystem atmosphere CO2 exchange. Agricultural and Forest Meteorology 214215, 515–531. Wehr R, J. W. Munger, D. D. Nelson, J. B. McManus, M. S. Zahniser, S. C. Wofsy, and S. R. Saleska (2013).Longterm eddy covariance measurements of the isotopic compositionof the ecosystem atmosphere exchange of CO2 in a temperate forest.Agricultural and Forest Meteorology 181, 6984.In press or in review:Abramoff RZ, Finzi AF. Seasonality and partitioning of root allocationto rhizosphere soils in a midlatitude forest. Ecosphere. (in press)Wehr R, J. W. Munger, J. B. McManus, D. D. Nelson, M. S. Zahniser,E. A. Davidson, S. C. Wofsy, and S. R. Saleska (2015). The seasonality of temperate forest photosynthesis and respiration. In review at Nature.
Research Org:
Woods Hole Research Center, Falmouth, MA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
54 ENVIRONMENTAL SCIENCES Forest; carbon; partitioning; eddy fluxes; belowground allocation; isotopes