Stem respiration and growth in a central Amazon rainforest
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); National Inst. for Amazon Research, Manaus (Brazil)
- National Inst. for Amazon Research, Manaus (Brazil)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- National Inst. for Amazon Research, Manaus (Brazil); Smithsonian Tropical Research Institute, Panama City (Panama)
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Washington State Univ., Pullman, WA (United States)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); National Inst. for Amazon Research, Manaus (Brazil); Univ. of California, Berkeley, CA (United States)
Key message: Annual stem CO2 efflux increases with stem wood production rates and are inhibited by daily moisture stress. Abstract: Tropical forests cycle a large amount of CO2 between the land and atmosphere, with a substantial portion of the return flux due tree respiratory processes. However, in situ estimates of woody tissue respiratory fluxes and carbon use efficiencies (CUEW) and their dependencies on physiological processes including stem wood production (Pw) and transpiration in tropical forests remain scarce. Here, we synthesize monthly Pw and daytime stem CO2 efflux (ES) measurements over 1 year from 80 trees with variable biomass accumulation rates in the central Amazon. On average, carbon flux to woody tissues, expressed in the same stem area normalized units as ES, averaged 0.90 ± 1.2 µmol m-2s-1 for Pw, and 0.55 ± 0.33 µmol m-2s-1 for daytime ES. A positive linear correlation was found between stem growth rates and stem CO2 efflux, with respiratory carbon loss equivalent to 15 ± 3% of stem carbon accrual. CUEW of stems was non-linearly correlated with growth and was as high as 77–87% for a fast-growing tree. Diurnal measurements of stem CO2 efflux for three individuals showed a daytime reduction of ES by 15–50% during periods of high sap flow and transpiration. The results demonstrate that high daytime ES fluxes are associated with high CUEW during fast tree growth, reaching higher values than previously observed in the Amazon Basin (e.g., maximum CUEW up to 77–87%, versus 30–56%). The observations are consistent with the emerging view that diurnal dynamics of stem water status influences growth processes and associated respiratory metabolism.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER)
- Grant/Contract Number:
- AC05-76RL01830; AC02-05CH11231; AC05-00OR22725
- OSTI ID:
- 1871899
- Alternate ID(s):
- OSTI ID: 1870601; OSTI ID: 1890661
- Report Number(s):
- PNNL-SA-169614
- Journal Information:
- Trees, Vol. 36, Issue 3; ISSN 0931-1890
- Publisher:
- SpringerCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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