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On the relative magnitudes of photosynthesis, respiration, growth and carbon storage in vegetation

Van Oijen, Marcel; Schapendonk, Ad; Höglind, Mats. 2010 On the relative magnitudes of photosynthesis, respiration, growth and carbon storage in vegetation. Annals of Botany, 105 (5). 793-797. 10.1093/aob/mcq039

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Abstract/Summary

Background and Aims: The carbon balance of vegetation is dominated by the two large fluxes of photosynthesis (P) and respiration (R). Mechanistic models have attempted to simulate the two fluxes separately, each with their own set of internal and external controls. This has led to model predictions where environmental change causes R to exceed P, with consequent dieback of vegetation. However, empirical evidence suggests that the R : P ratio is constrained to a narrow range of about 0·4–0·5. Physiological explanations for the narrow range are not conclusive. The aim of this work is to introduce a novel perspective by theoretical study of the quantitative relationship between the four carbon fluxes of P, R, growth and storage (or its inverse, remobilization). Methods: Starting from the law of conservation of mass – in this case carbon – equations are derived for the relative magnitudes of all carbon fluxes, which depend on only two parameters: the R : P ratio and the relative rate of storage of carbon in remobilizable reserves. The equations are used to explain observed flux ratios and to analyse incomplete data sets of carbon fluxes. Key Results: The storage rate is shown to be a freely varying parameter, whereas R : P is narrowly constrained. This explains the constancy of the ratio reported in the literature. With the information thus gained, a data set of R and P in grassland was analysed, and flux estimates could be derived for the periods after cuts in which plant growth is dominated by remobilization before photosynthesis takes over. Conclusions: It is concluded that the relative magnitudes of photosynthesis, respiration, growth and substrate storage are indeed tightly constrained, but because of mass conservation rather than for physiological reasons. This facilitates analysis of incomplete data sets. Mechanistic models, as the embodiment of physiological mechanisms, need to show consistency with the constraints.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1093/aob/mcq039
Programmes: CEH Topics & Objectives 2009 onwards > Biogeochemistry > BGC Topic 1 - Monitoring and Interpretation of Biogeochemical and Climate Changes
CEH Topics & Objectives 2009 onwards > Biogeochemistry > BGC Topic 2 - Biogeochemistry and Climate System Processes
CEH Programmes pre-2009 publications > Biogeochemistry > BG01 Measuring and modelling trace gas, aerosol and carbon > BG01.2 Carbon
CEH Sections: Billett
ISSN: 0305-7364
NORA Subject Terms: Biology and Microbiology
Ecology and Environment
Earth Sciences
Date made live: 23 Jun 2010 09:27
URI: http://nora.nerc.ac.uk/id/eprint/9654

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