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  • 1
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Previous modelling exercises and conceptual arguments have predicted that a reduction in biochemical capacity for photosynthesis (Aarea) at elevated CO2 may be compensated by an increase in mesophyll tissue growth if the total amount of photosynthetic machinery per unit leaf area is maintained (i.e. morphological upregulation). The model prediction was based on modelling photosynthesis as a function of leaf N per unit leaf area (Narea), where Narea = Nmass×LMA. Here, Nmass is percentage leaf N and is used to estimate biochemical capacity and LMA is leaf mass per unit leaf area and is an index of leaf morphology. To assess the relative importance of changes in biochemical capacity versus leaf morphology we need to control for multiple correlations that are known, or that are likely to exist between CO2 concentration, Narea, Nmass, LMA and Aarea. Although this is impractical experimentally, we can control for these correlations statistically using systems of linear multiple-regression equations. We developed a linear model to partition the response of Aarea to elevated CO2 into components representing the independent and interactive effects of changes in indexes of biochemical capacity, leaf morphology and CO2 limitation of photosynthesis. The model was fitted to data from three pine and seven deciduous tree species grown in separate chamber-based field experiments. Photosynthetic enhancement at elevated CO2 due to morphological upregulation was negligible for most species. The response of Aarea in these species was dominated by the reduction in CO2 limitation occurring at higher CO2 concentration. However, some species displayed a significant reduction in potential photosynthesis at elevated CO2 due to an increase in LMA that was independent of any changes in Narea. This morphologically based inhibition of Aarea combined additively with a reduction in biochemical capacity to significantly offset the direct enhancement of Aarea caused by reduced CO2 limitation in two species. This offset was 100% for Acer rubrum, resulting in no net effect of elevated CO2 on Aarea for this species, and 44% for Betula pendula. This analysis shows that interactions between biochemical and morphological responses to elevated CO2 can have important effects on photosynthesis.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 19 (1996), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We describe the use of a unique plant growth facility, which has as its centerpiece four ‘EcoCELLs’, or 5x7 m mesocosms designed as open-flow, mass-balance systems for the measurement of carbon, water and trace gas fluxes. This system is unique in that it was conceived specifically to bridge the gap between measurement scales during long-term experiments examining the function and development of model ecosystems. There are several advantages to using EcoCELLs, including (i) the same theory of operation as leaf level gas exchange systems, but with continuous operation at a much larger scale: (ii) the ability to independently evaluate canopy-level and ecosystem models; (iii) simultaneous manipulation of environmental factors and measurement of system-level responses, and (iv) maximum access to, and manipulation of, a large rooting volume.In addition to discussing the theory, construction and relative merits of EcoCELLs, we describe the calibration and use of the EcoCELLs during a ‘proof of concept’ experiment. This experiment involved growing soybeans under two ambient CO2 concentrations (−360 and 710μmol mol−1. During this experiment, we asked ‘How accurate is the simplest model that can be used to scale from leaf-level to canopy-level responses?’ in order to illustrate the utility of the EcoCELLs in validating canopy-scale models.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 13 (1990), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Coefficients describing the sensitivity of the rate of photosynthetic carbon dioxide fixation to small changes in the stomatal conductance and boundary layer conductance are derived. These sensitivity or ‘control’ coefficients, together with those for the carboxylase and oxygenase activities of ribulose 1,5-bisphosphate carboxylase/oxygenase, are calculated from standard gas exchange data and apply under conditions where leaf temperature and water vapour concentration at the leaf surface remain largely constant. It is shown that the magnitude of the control coefficients depends on conditions such as photon flux density, ambient CO2 concentration and relative humidity at the leaf surface. The extension of this analysis to encompass the sensitivity of the photosynthetic fluxes to changes in enzyme concentrations and kinetic properties is also discussed.
    Type of Medium: Electronic Resource
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  • 4
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    Menasha, Wis. : Periodicals Archive Online (PAO)
    The Accounting Review. 42:4 (1967:Oct.) 813 
    ISSN: 0001-4826
    Topics: Economics
    Description / Table of Contents: BOOK REVIEWS, CHARLES H. GRIFFIN, Editor
    Notes: Departments
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 224 (2000), S. 99-113 
    ISSN: 1573-5036
    Keywords: CO2 ; nitrogen fertilization ; soils ; nutrients ; Pinus ponderosa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of six years treatment with elevated [CO2] (350, 525, and 700 μl l-1) and nitrogen (N) (0, 10, and 20 g N m-2 yr-1) on soils, soil solution, and CO2 efflux in an open-top chamber study with ponderosa pine (Pinus ponderosa Laws.) are described. The clearest [CO2] effect was in year 6, when a pattern of lower soil N concentration and higher C/N ratio with elevated [CO2] emerged. Statistically significant effects of elevated [CO2] on soil total C, extractable P, exchangeable Mg2+, exchangeable Ca2+, base saturation, and soil solution HCO3 - and NO3 - were also found in various treatment combinations and at various times; however, these effects were inconsistent among treatments and years, and in many cases (P, Mg2+, Ca2+, base saturation) reflected pre-treatment differences. The use of homogenized buried soil bags did not improve the power to detect changes in soil C and N or help resolve the inconsistencies in soil C patterns. Nitrogen fertilization had the expected negative effects on exchangeable Ca2+, K+, and Mg2+ in year 6, presumably because of increased NO3 - leaching, but had no consistent effect on soil C, N, or extractable P.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Water, air & soil pollution 85 (1995), S. 1551-1556 
    ISSN: 1573-2932
    Keywords: Nitrogen ; Carbon dioxide ; Phosphorus ; Calcium ; Potassium ; Magnesium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This paper describes the effects of elevated CO2 and N fertilization on soils planted with ponderosa pine (Pinus ponderosa) seedlings in short-term greenhouse studies. The high degree of homogeneity in the soils used allowed sensitive evaluation of soil changes in response to treatments. Elevated CO2 had no detectable effect upon soil N availability, but both CO2 and N fertilization caused significant changes in soil available (NH4F/HCl-extractable) P. Some of these changes could be accounted for by plant uptake, some were apparently due to differences in P immobilization (biotic or abiotic). N fertilization caused reductions in exchangeable K, Ca and Mg which could not be accounted for by plant uptake and were probably due to increased leaching. None of the reductions in soil available nutrients observed were of sufficient magnitude to cause nutrient deficiencies over the approximate 1-year duration of these studies.
    Type of Medium: Electronic Resource
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