Determining the relationship between tree-stem respiration and CO2 efflux by δO2/Ar measurements.

Respiration in forest tree stems is an important component of the global carbon cycle. This respiration is traditionally estimated by measurements of the CO(2) efflux from the stem. However, recent studies have suggested that movement of CO(2) in the transpiration stream causes large errors in the respiration estimated by the CO(2) efflux. Here we demonstrate a new approach for determining the ratio of respiration to CO(2) efflux, which is based on specially designed chambers, and combined CO(2) and O(2) measurements. The high accuracy O(2) measurement is performed by mass spectrometric measurement of the O(2)/Ar ratio. Testing the method gave repeatable results which point that in some conditions up to 40% of the respired CO(2) can be carried away from the site of respiration.

[1]  R. Matyssek,et al.  Seasonal patterns of carbon allocation to respiratory pools in 60-yr-old deciduous (Fagus sylvatica) and evergreen (Picea abies) trees assessed via whole-tree stable carbon isotope labeling. , 2011, The New phytologist.

[2]  J. Marshall,et al.  A new method to measure carbon isotope composition of CO2 respired by trees: stem CO2 equilibration , 2009 .

[3]  J. Marshall,et al.  Storage and transpiration have negligible effects on delta13C of stem CO2 efflux in large conifer trees. , 2009, Tree physiology.

[4]  R. Teskey,et al.  Measurement of stem respiration of sycamore (Platanus occidentalis L.) trees involves internal and external fluxes of CO2 and possible transport of CO2 from roots. , 2007, Plant, cell & environment.

[5]  R. Teskey,et al.  Estimating stem respiration in trees by a mass balance approach that accounts for internal and external fluxes of CO2. , 2004, Tree physiology.

[6]  E. Barkan,et al.  High-precision measurements of 17O/16O and 18O/16O of O2 and O2/Ar ratio in air. , 2003, Rapid communications in mass spectrometry : RCM.

[7]  R. Teskey,et al.  Carbon dioxide transport in xylem causes errors in estimation of rates of respiration in stems and branches of trees , 2002 .

[8]  D. Yakir,et al.  Fractionation of oxygen isotopes by respiration and diffusion in soils and its implications for the isotopic composition of atmospheric O2 , 2001 .

[9]  W. Massman.  A review of the molecular diffusivities of H2O, CO2, CH4, CO, O3, SO2, NH3, N2O, NO, and NO2 in air O2 and N2 near STP , 1998 .

[10]  M. Williams,et al.  Net primary production of forests: a constant fraction of gross primary production? , 1998, Tree physiology.

[11]  M. G. Ryan,et al.  Annual carbon cost of autotrophic respiration in boreal forest ecosystems in relation to species and climate , 1997 .

[12]  R. J. Millington,et al.  Diffusion in Aggregated Porous Media , 1971 .

[13]  P. Hietz,et al.  Gas diffusion through wood: implications for oxygen supply , 2005, Trees.

[14]  E. DeLucia,et al.  Stem maintenance and construction respiration in Pinus ponderosa grown in different concentrations of atmospheric CO(2). , 1996, Tree physiology.