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  • 1
    Electronic Resource
    Electronic Resource
    Long-term photosynthetic response in single leaves of A C3 and C4 salt marsh species grown at elevated atmospheric CO2 in situ (1990)
    Springer
    Oecologia 83 (1990), S. 469-472 
    Details
    ISSN: 1432-1939
    Keywords: Acclimation ; Photosynthetic photon flux ; Elevated CO2 ; Scirpus olneyi ; Spartina patens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mono-specific communities of the C3 sedge, Scirpus olneyi and the C4 grass, Spartina patens, were exposed to normal ambient or elevated CO2, (ca. 680 μl l−1) throughout the 1987 and 1988 growing seasons in open-top field chambers located on a tidal marsh. Single stems of C3 plants grown in ambient or elevated CO2 showed an increased photosynthetic rate when tested at elevated CO2 for both seasons. This increase in photosynthetic response in the C3 species was maintained throughout the 1987 and 1988 growing season. The stimulation of photosynthesis with elevated CO2 appeared to increase as temperature increased and decreased as photosynthetic photon flux (PPF) increased. Analysis of the photosynthetic response of the C3 species during the 1988 season indicated that significant differences in light-saturated photosynthetic rate between ambient and elevated CO2 conditions continued until October. In contrast to the C3 sedge, the C4 grass showed no significant photosynthetic increase to elevated CO2 except at the beginning of the 1988 season.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00317196
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Open top chambers for exposing plant canopies to elevated CO2 concentration and for measuring net gas exchange (1993)
    Springer
    Plant ecology 104-105 (1993), S. 3-15 
    Details
    ISSN: 1573-5052
    Keywords: Open top chamber ; Gas exchange ; Photosynthesis ; Elevated CO2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Open top chamber design and function are reviewed. All of the chambers described maintain CO2 concentrations measured at a central location within ±30 ppm of a desired target when averaged over the growing season, but the spatial and temporal range within any chamber may be closer to 100 ppm. Compared with unchambered companion plots, open top chambers modify the microenvironment in the following ways: temperatures are increased up to 3°C depending on the chamber design and location of the measurement; light intensity is typically diminished by as much as 20%; wind velocity is lower and constant; and relative humidity is higher. The chamber environment may significantly alter plant growth when compared with unchambered controls, but the chamber effect on growth has not been clearly attributed to a single or even a few environmental factors. A method for modifying an open top chamber for tracking gas exchange between natural vegetation and the ambient air is described. This modification consists of the addition of a top with exit chimney to reduce dilution of chamber CO2 by external ambient air, is quickly made and permits estimation of the effects of elevated CO2 and water vapor exchange. The relatively simple design and construction of open top chambers make them the most likely method to be used in the near future for long-term elevated CO2 exposure of small trees, crops and grassland ecosystems. Improvements in the basic geometry to improve control of temperature, reduce the variation of CO2 concentrations, and increase the turbulence and wind speed in the canopy boundary layer are desirable objectives. Similarly, modifications for measuring water vapor and carbon dioxide gas exchange will extend the usefulness of open top chambers to include non-destructive monitoring of the responses of ecosystems to rising atmospheric CO2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00048141
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Acclimation of photosynthesis, respiration and ecosystem carbon flux of a wetland on Chesapeake Bay, Maryland to elevated atmospheric CO2 concentration (1995)
    Springer
    Plant and soil 187 (1995), S. 111-118 
    Details
    ISSN: 1573-5036
    Keywords: acclimation ; ecosystem carbon balance ; elevated CO2 ; global change ; photosynthesis ; respiration ; soil carbon ; soil organic matter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Acclimation of photosynthesis and respiration in shoots and ecosystem carbon dioxide fluxes to rising atmospheric carbon dioxide concentration (C a ) was studied in a brackish wetland. Open top chambers were used to create test atmospheres of normal ambient and elevated C a (=normal ambient + 34 Pa CO2) over mono-specific stands of the C3 sedge Scirpus olneyi, the dominant C3 species in the wetland ecosystem, throughout each growing season since April of 1987. Acclimation of photosynthesis and respiration were evaluated by measurements of gas exchange in excised shoots. The impact of elevated C a on the accumulation of carbon in the ecosystem was determined by ecosystem gas exchange measurements made using the open top chamber as a cuvette. Elevated C a increased carbohydrate and reduced Rubisco and soluble protein concentrations as well as photosynthetic capacity(A) and dark respiration (R d ; dry weight basis) in excised shoots and canopies (leaf area area basis) of Scirpus olneyi. Nevertheless, the rate of photosynthesis was stimulated 53% in shoots and 30% in canopies growing in elevated C a compared to normal ambient concentration. Elevated C a inhibited R d measured in excised shoots (−19 to −40%) and in seasonally integrated ecosystem respiration (R e ; −36 to −57%). Growth of shoots in elevated C a was stimulated 14–21%, but this effect was not statistically significant at peak standing biomass in midseason. Although the effect of elevated C a on growth of shoots was relatively small, the combined effect of increased number of shoots and stimulation of photosynthesis produced a 30% stimulation in seasonally integrated gross primary production (GPP). The stimulation of photosynthesis and inhibition of respiration by elevated C a increased net ecosystem production (NEP=GPP−R e ) 59% in 1993 and 50% in 1994. While this study consistently showed that elevated C a produced a significant increase in NEP, we have not identified a correspondingly large pool of carbon below ground.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00017084
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The influence of atmospheric CO2 enrichment on plant-soil nitrogen interactions in a wetland plant community on the Chesapeake Bay (1999)
    Springer
    Plant and soil 210 (1999), S. 93-101 
    Details
    ISSN: 1573-5036
    Keywords: denitrification ; elevated CO2 ; exchangeable N (NH 4 + ) ; potential net N mineralization ; Scirpus olneyi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We investigated plant and soil nitrogen pools and soil processes in monospecific stands of the C3 sedge Scirpus olneyi and the C4 grass Spartina patens grown in the field in open top chambers in a brackish marsh on the Chesapeake Bay. Stands of S. olneyi responded to eight years of elevated CO2, by increased rates of net ecosystem gas exchange and a large stimulation of net ecosystem production. We conducted our study in the summer of 1994 and 1995 when soil cores were collected and aboveground biomass was estimated. Nitrogen concentration in elevated CO2 treatments was reduced 15% in stems of S. olneyi and 8% in the upper 10 cm of the soil profile. While total plant nitrogen per unit of land area remained the same between treatments, total soil nitrogen showed a non-significant tendency to decrease in the upper 10 cm of the soil profile in elevated CO2 both years of study. A significant decrease in soil bulk density largely contributed to the observed decrease in soil nitrogen. Exchangeable nitrogen and potential denitrification rates were also reduced in elevated CO2, but net nitrogen mineralization was unchanged by elevated CO2 treatment in S. olneyi both years. Plants and soils in a pure stand of the C4 grass, S. patens, showed none of these effects of elevated CO2 treatment. Our data provides evidence of changes in nitrogen dynamics of an ecosystem exposed to elevated CO2 for eight years; however due to the variability in these data, we cannot say if or how these changes are likely to impact the effect of rising CO2 on primary production or carbon accumulation in this ecosystem in the future.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004690220705
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    Paper (German National Licenses)
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