scholarly journals Carbon dioxide exchange of Scots pine shoots as estimated by a biochemical model and cuvette field measurements

Silva Fennica ◽  
1998 ◽  
Vol 32 (4) ◽  
Author(s):  
Tuula Aalto
Keyword(s):  
Carbon Dioxide ◽  
Scots Pine ◽  
Field Measurements ◽  
Carbon Dioxide Exchange ◽  
Biochemical Model

Description of a dynamic closed chamber for measuring soil respiration and its comparison with other techniques

1997 ◽  
Vol 77 (2) ◽  
pp. 195-203 ◽  
Author(s):  
P. Rochette ◽  
B. Ellert ◽  
E. G. Gregorich ◽  
R. L. Desjardins ◽  
E. Pattey ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Soil Respiration ◽  
Field Measurements ◽  
Eddy Correlation ◽  
Carbon Dioxide Exchange ◽  
Closed Chamber ◽  
Dynamic Chamber ◽  
New Information ◽  
The Difference ◽  
Good Agreement

Soil respiration is an important component of the net carbon dioxide exchange between agricultural ecosystems and the atmosphere, and reliable estimates of soil respiration are required in carbon balance studies. Most of the field measurements of soil respiration reported in the literature have been made using alkali traps. The use of portable CO2 analysers in dynamic closed chamber systems is recent. The introduction of this new technique requires its evaluation against existing methods in order to compare new information with older data. Nine intercomparisons between dynamic systems and alkali traps were made. Measurements of Fc,s obtained by both chambers showed a good agreement in all but two comparisons in which alkali trap measurements were lower than the dynamic chamber by about 22%. This first report of agreement between both techniques suggests that many measurements made in the past using alkali traps may be comparable to the measurements made more recently using the dynamic chambers. Analysis of the soil temperature and CO2 concentration inside the alkali traps failed to explain why the alkali traps occasionally underestimated the fluxes. Soil respiration measured with a dynamic closed chamber were also compared to eddy-correlation measurements. The results did not reveal any consistent bias between techniques but the scattering was large. This dispersion is likely the result of the difference between the areas measured by the two techniques. Key words: Carbon dioxide, greenhouse gases, CO2 flux, soil carbon

Field measurements of carbon dioxide exchange of the Antarctic lichen Usnea sphacelata in the frozen state

1989 ◽  
Vol 1 (1) ◽  
pp. 31-34 ◽  
Author(s):  
L. Kappen
Keyword(s):  
Carbon Dioxide ◽  
Field Measurements ◽  
Carbon Dioxide Exchange ◽  
Carbon Dioxide Uptake ◽  
Carbon Production ◽  
Continental Antarctica ◽  
Infra Red ◽  
Wilkes Land ◽  
The Antarctic ◽  
Slow Growing

Field measurements of CO2 exchange were made with an infra-red gas analyser system on lichens at Bailey Peninsula, Wilkes Land, continental Antarctica. It has been demonstrated that Usnea sphacelata, a prominent element of the cryptogamic vegetation of this area, became photosynthetically active at temperatures below 0°C when the thalli were covered by drifted snow. Carbon dioxide uptake was detected down to −10°C. The carbon production during such a ‘frost’ day was considerable for a slow-growing Antarctic lichen. The importance of snow for production in lichens is emphasized. The mechanism of water uptake when the thalli are frozen needs further investigation.

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