23 Predictions and Measurements
of the Maximum Photosynthetic Rate, Amax,
at the Global Scale
F.I. Woodward and T.M. Smith
23.1 Introduction
The study of plant photosynthesis has an exceptionally long pedigree, because photosynthesis is the primary source of chemical energy for plants,
animals, and for integrated ecosystem functioning. The central importance
of photosynthesis in ecology was clearly stated by Lange et al. (1987) "Thus
photosynthetic primary production is not only a requirement for the single
plant but the essential energy-harvesting process for the total biosphere. If
we want to understand how ecosystems function, we must analyze the
photosynthetic performance of the relevant plants".
This view is generally held and, as a consequence, strong research schools
and approaches have developed, based on photosynthesis as the central
process. The measurement of photosynthesis in the field and in relation to
plant distribution has been dominated in Europe by Lange and his coworkers (e.g., Lange 1965; Schulze and Hall 1982; Lange et al. 1984), with
significant studies also by North Americans (Mooney and West 1964; Mooney
et al. 1966). These pioneering studies have been followed by studies and
approaches which aimed to compare and contrast photosynthetic properties
in very different ecosystems but with the same mechanistic base. The concentration of leaf nitrogen has been the dominant base, as it is an easy
measure which is correlated with the concentration of the photosynthetic
apparatus and enzymes (Field 1983; Field and Mooney 1986; Evans 1989).
The search for a general mechanistic base to photosynthesis was further
extended by the mathematical modeling of the rate-limiting processes
(Farquhar and von Caemmerer 1982; Farquhar 1988), an approach which
through its mechanistic rather than empirical base has greatly improved the
predictive capacity of photosynthetic models (Leuning 1990).
Given the extensive interest in predicting the effects of global climate
change on the ecosystems of the World (Melillo et al. 1990) and the central
importance of photosynthesis to ecosystem processes (Lange et al. 1987), it
is important to take stock of the current range of photosynthetic capacities
at a global scale so that the responses to environmental change can be
predicted from a sound process and data base. This chapter aims to develop
a general model for predicting the maximum rate of terrestrial photo-
of the Maximum Photosynthetic Rate, Amax,
at the Global Scale
F.I. Woodward and T.M. Smith
23.1 Introduction
The study of plant photosynthesis has an exceptionally long pedigree, because photosynthesis is the primary source of chemical energy for plants,
animals, and for integrated ecosystem functioning. The central importance
of photosynthesis in ecology was clearly stated by Lange et al. (1987) "Thus
photosynthetic primary production is not only a requirement for the single
plant but the essential energy-harvesting process for the total biosphere. If
we want to understand how ecosystems function, we must analyze the
photosynthetic performance of the relevant plants".
This view is generally held and, as a consequence, strong research schools
and approaches have developed, based on photosynthesis as the central
process. The measurement of photosynthesis in the field and in relation to
plant distribution has been dominated in Europe by Lange and his coworkers (e.g., Lange 1965; Schulze and Hall 1982; Lange et al. 1984), with
significant studies also by North Americans (Mooney and West 1964; Mooney
et al. 1966). These pioneering studies have been followed by studies and
approaches which aimed to compare and contrast photosynthetic properties
in very different ecosystems but with the same mechanistic base. The concentration of leaf nitrogen has been the dominant base, as it is an easy
measure which is correlated with the concentration of the photosynthetic
apparatus and enzymes (Field 1983; Field and Mooney 1986; Evans 1989).
The search for a general mechanistic base to photosynthesis was further
extended by the mathematical modeling of the rate-limiting processes
(Farquhar and von Caemmerer 1982; Farquhar 1988), an approach which
through its mechanistic rather than empirical base has greatly improved the
predictive capacity of photosynthetic models (Leuning 1990).
Given the extensive interest in predicting the effects of global climate
change on the ecosystems of the World (Melillo et al. 1990) and the central
importance of photosynthesis to ecosystem processes (Lange et al. 1987), it
is important to take stock of the current range of photosynthetic capacities
at a global scale so that the responses to environmental change can be
predicted from a sound process and data base. This chapter aims to develop
a general model for predicting the maximum rate of terrestrial photo-