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  • 1
    Electronic Resource
    Electronic Resource
    The photosynthesis – leaf nitrogen relationship at ambient and elevated atmospheric carbon dioxide: a meta-analysis (1999)
    Oxford, UK : Blackwell Science Ltd
    Global change biology 5 (1999), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Estimation of leaf photosynthetic rate (A) from leaf nitrogen content (N) is both conceptually and numerically important in models of plant, ecosystem, and biosphere responses to global change. The relationship between A and N has been studied extensively at ambient CO2 but much less at elevated CO2. This study was designed to (i) assess whether the A–N relationship was more similar for species within than between community and vegetation types, and (ii) examine how growth at elevated CO2 affects the A–N relationship. Data were obtained for 39 C3 species grown at ambient CO2 and 10 C3 species grown at ambient and elevated CO2. A regression model was applied to each species as well as to species pooled within different community and vegetation types. Cluster analysis of the regression coefficients indicated that species measured at ambient CO2 did not separate into distinct groups matching community or vegetation type. Instead, most community and vegetation types shared the same general parameter space for regression coefficients. Growth at elevated CO2 increased photosynthetic nitrogen use efficiency for pines and deciduous trees. When species were pooled by vegetation type, the A–N relationship for deciduous trees expressed on a leaf-mass basis was not altered by elevated CO2, while the intercept increased for pines. When regression coefficients were averaged to give mean responses for different vegetation types, elevated CO2 increased the intercept and the slope for deciduous trees but increased only the intercept for pines. There were no statistical differences between the pines and deciduous trees for the effect of CO2. Generalizations about the effect of elevated CO2 on the A–N relationship, and differences between pines and deciduous trees will be enhanced as more data become available.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2486.1999.00234.x
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  • 2
    Electronic Resource
    Electronic Resource
    Short-term fitness benefits of physiological integration in the clonal herb Hydrocotyle peduncularis (2002)
    Oxford, UK : Blackwell Science Pty
    Austral ecology 27 (2002), S. 0 
    Details
    ISSN: 1442-9993
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract  We test whether physiological integration enhances the short-term fitness of the clonal herb Hydrocotyle peduncularis (Apiaceae, R. Brown ex A. Richards) subjected to spatial variation in water availability. Our measures of fitness and costs and benefits are based on the relative growth rate of fragmented genets. Physiological integration over a gradient in soil moisture resulted in a highly significant net benefit to genet growth of 0.015 g g−1 day−1. This net benefit represents a significant enhancement of the average fitness of fragmented genets spanning the moisture gradient relative to the average of those growing in homogeneous moist or dry conditions. Sections of genet fragments growing in dry conditions in spatially heterogeneous treatments had significantly higher growth than the sections they were connected to that were growing in moist conditions. Within fragments, older (parent) sections growing in moist conditions experienced significant costs from connection to younger (offspring) sections growing in dry conditions. In contrast, offspring sections with ample water did not experience any costs when connected to parent sections growing in dry conditions. However, the net benefit of physiological integration was similar for parent and offspring sections, suggesting that parent and offspring sections contributed equally to the net benefit of physiological integration to genet growth and short-term fitness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1442-9993.2002.01219.x
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  • 3
    Electronic Resource
    Electronic Resource
    Reconciling the apparent difference between mass- and area-based expressions of the photosynthesis-nitrogen relationship (1999)
    Springer
    Oecologia 118 (1999), S. 144-150 
    Details
    ISSN: 1432-1939
    Keywords: Key words Photosynthesis ; Leaf nitrogen ; Leaf mass per area
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationship between photosynthetic carbon assimilation (A max) and leaf nitrogen content (N leaf) can be expressed on either a leaf area basis (A area vs N area) or a leaf mass basis (A mass vs N mass). Dimensional analysis shows that the units for the slope of this relationship are the same for both expressions (μmol [CO2] g−1 [N] s−1). Thus the slope measures the change in CO2 assimilation per gram of nitrogen, independent of leaf mass or leaf area. Although they have the same units, large differences between the area and mass-based slopes have been observed over a broad range of taxonomically diverse species. Some authors have claimed that regardless of these differences, the fundamental nature of the A max-N leaf relationship is independent of the units of expression. In contrast, other authors have claimed that the area-based A max-N leaf relationship is fundamentally different from the mass-based relationship because of interactions between A max, N leaf, and leaf mass per area (LMA, g [leaf] m−2 [leaf]). In this study we consider the mathematical relationships involved in the transformation from mass- to area-based expressions (and vice versa), and the implications this transformation has for the slope of the A max-N leaf relationship. We then show that the slope of the relationship is independent of the units of expression when the effect of LMA is controlled statistically using a multiple regression. The validity of this hypothesis is demonstrated using 13 taxonomically and functionally diverse C3 species. This analysis shows that the slope of the A max-N leaf relationship is similar for the mass- and area-based expressions and that significant errors in the estimate of the slope can arise when the effect of LMA is not controlled.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050712
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    Paper (German National Licenses)
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