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

scholarly journals Carbon exchange between the atmosphere and subtropical forested cypress and pine wetlands

2015 ◽  
Vol 12 (8) ◽  
pp. 2285-2300 ◽  
Author(s):  
W. B. Shoemaker ◽  
F. Anderson ◽  
J. G. Barr ◽  
S. L. Graham ◽  
D. B. Botkin
Keyword(s):  
Carbon Dioxide ◽  
Vegetation Index ◽  
Overland Flow ◽  
Net Ecosystem Exchange ◽  
Forested Wetland ◽  
Carbon Dioxide Exchange ◽  
Ecosystem Carbon ◽  
Heterotrophic Soil Respiration ◽  
The Difference ◽  
Carbon Dioxide Co2

Abstract. Carbon dioxide exchange between the atmosphere and forested subtropical wetlands is largely unknown. Here we report a first step in characterizing this atmospheric–ecosystem carbon (C) exchange, for cypress strands and pine forests in the Greater Everglades of Florida as measured with eddy covariance methods at three locations (Cypress Swamp, Dwarf Cypress and Pine Upland) for 2 years. Links between water and C cycles are also examined at these three sites, as are methane emission measured only at the Dwarf Cypress site. Each forested wetland showed net C uptake from the atmosphere both monthly and annually, as indicated by the net ecosystem exchange (NEE) of carbon dioxide (CO2). For this study, NEE is the difference between photosynthesis and respiration, with negative values representing uptake from the atmosphere that is retained in the ecosystem or transported laterally via overland flow (unmeasured for this study). Atmospheric C uptake (NEE) was greatest at the Cypress Swampp (−900 to −1000 g C m2 yr−1), moderate at the Pine Upland (−650 to −700 g C m2 yr−1) and least at the Dwarf Cypress (−400 to −450 g C m2 yr−1). Changes in NEE were clearly a function of seasonality in solar insolation, air temperature and flooding, which suppressed heterotrophic soil respiration. We also note that changes in the satellite-derived enhanced vegetation index (EVI) served as a useful surrogate for changes in NEE at these forested wetland sites.

Carbon dioxide exchange by native Great Plains grasses

1971 ◽  
Vol 49 (8) ◽  
pp. 1341-1345 ◽  
Author(s):  
Robert E. Redmann
Keyword(s):  
Carbon Dioxide ◽  
Soil Respiration ◽  
Water Potential ◽  
Plant Communities ◽  
Great Plains ◽  
Net Photosynthesis ◽  
Moisture Stress ◽  
Bouteloua Gracilis ◽  
Carbon Dioxide Exchange ◽  
Western North Dakota

Carbon dioxide exchange in relation to light and moisture stress was determined for dominants of three grassland plant communities of western North Dakota. These range from Bouteloua gracilis on very dry sites to Stipa viridula on less dry positions to Sporobolus heterolepis in moist ravines. Maximum net photosynthesis of sod transplants ranged from 10 to 12 mg CO2 g−1 h−1 (6 × 104 lx), corrected for soil respiration of about 3 mg CO2 dm−1 h−1. In B. gracilis and S. viridula, net photosynthesis declined steadily to 25% of maximum when moisture stress was increased to −30 bars soil matric water potential. Net photosynthesis declined less rapidly in S. heterolepis when moisture stress increased to −10 bars, but decreased to zero when stress reached −30 bars. The implications regarding distribution of the species are discussed.

COMPARISON OF PHOTOSYNTHESIS IN NORMAL AND TRIAZINE-RESISTANT Brassica

1987 ◽  
Vol 67 (2) ◽  
pp. 457-466 ◽  
Author(s):  
S. L. A. HOBBS
Keyword(s):  
Carbon Dioxide ◽  
Exchange Rate ◽  
Chlorophyll A ◽  
Dry Weight ◽  
Stomatal Resistance ◽  
Carbon Dioxide Exchange ◽  
Shoot Dry Weight ◽  
Significant Difference ◽  
The Difference ◽  
Net Assimilation

In spaced field plantings, triazine-resistant types of Brassica campestris L. and B. napus L. had a carbon dioxide exchange rate (CER) 28% lower in 1983 and 25% lower in 1984 than normal (triazine-susceptible) types. In plots simulating agronomic spacings in 1984, the difference between CER in normal and resistant types was 17% for B. campestris, 14% for B. napus and 13% for B. juncea L. Differences were apparent throughout the season and were not associated with any particular stage of growth. Resistant progeny from reciprocal crosses between resistant and susceptible plants of B. napus exhibited reduced CER at all levels of photosynthetically active radiation and at all temperatures. There was no significant difference between plant types for chlorophyll a + b content or chlorophyll a/b ratio. Shoot dry weight, stomatal resistance and specific leaf weight were higher in the normal types, but there was no difference between types in either relative growth rate or net assimilation rate. The reduced biomass was not therefore linked to reduced CER.Key words: Carbon dioxide exchange rate, herbicide, oilseed, rapeseed

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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