Goetz, S. J. and S. D. Prince. 1999. Advances in Ecological Research Vol.28, Pages 58-92.
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A hypothesis of "functional convergence" has been proposed that links natural selection with a narrow range of light use efficiencies among a wide range of plant functional types. This hypothesis is important because it suggests how estimates of terrestrial productivity might be achieved with remotely sensed measurements of light absorption by terrestrial vegetation. We examine the strength of the links between light availability, foliage display, and canopy reflectance to determine the utility of the hypothesis for modeling primary production.
Evidence for functional convergence arises from optimization of resource use efficiencies as a result of allocation strategies and trade-offs in associated carbon (energy) and nutrient (protein) costs relative to benefits. Convergence is most evident on a leaf mass per unit ground area basis, a measure that reflects the costs of resource acquisition. The links between maximization of fitness and carbon gain, while clearly and causally related to gross primary production, do not obviously extend to net primary production other than through a common basis in CO2 assimilation.
We demonstrate how convergence is to be expected on gross production due to differences in respiratory costs associated with synthesis and maintenance of plant constituents and associated "paybak intervals" on carbon investment in different functional types. Other factors related to the decoupling of light absorption and utilization are discussed. We conclude that, while functional convergence provides a basis for the use of remote sensing of light absorption in measurement of primary production, models driven with light absorption need to include terms that describe both the actual photosynthesis and respiratory costs of maintenance and synthesis. Quantification of these processes will improve global primary production models, and enhance the value of the information that can be acquired by remote sensing.