Book contents
- Frontmatter
- Contents
- Preface
- List of symbols
- 1 The general nature of biosphere-atmosphere fluxes
- 2 Thermodynamics, work, and energy
- 3 Chemical reactions, enzyme catalysts, and stable isotopes
- 4 Control over metabolic fluxes
- 5 Modeling the metabolic CO2 flux
- 6 Diffusion and continuity
- 7 Boundary layer and stomatal control over leaf fluxes
- 8 Leaf structure and function
- 9 Water transport within the soil-plant-atmosphere continuum
- 10 Leaf and canopy energy budgets
- 11 Canopy structure and radiative transfer
- 12 Vertical structure and mixing of the atmosphere
- 13 Wind and turbulence
- 14 Observations of turbulent fluxes
- 15 Modeling of fluxes at the canopy and landscape scales
- 16 Soil fluxes of CO2, CH4, and NOx
- 17 Fluxes of biogenic volatile compounds between plants and the atmosphere
- 18 Stable isotope variants as tracers for studying biosphere-atmosphere exchange
- References
- Index
- Plate Section
5 - Modeling the metabolic CO2 flux
Published online by Cambridge University Press: 05 June 2014
- Frontmatter
- Contents
- Preface
- List of symbols
- 1 The general nature of biosphere-atmosphere fluxes
- 2 Thermodynamics, work, and energy
- 3 Chemical reactions, enzyme catalysts, and stable isotopes
- 4 Control over metabolic fluxes
- 5 Modeling the metabolic CO2 flux
- 6 Diffusion and continuity
- 7 Boundary layer and stomatal control over leaf fluxes
- 8 Leaf structure and function
- 9 Water transport within the soil-plant-atmosphere continuum
- 10 Leaf and canopy energy budgets
- 11 Canopy structure and radiative transfer
- 12 Vertical structure and mixing of the atmosphere
- 13 Wind and turbulence
- 14 Observations of turbulent fluxes
- 15 Modeling of fluxes at the canopy and landscape scales
- 16 Soil fluxes of CO2, CH4, and NOx
- 17 Fluxes of biogenic volatile compounds between plants and the atmosphere
- 18 Stable isotope variants as tracers for studying biosphere-atmosphere exchange
- References
- Index
- Plate Section
Summary
It is perhaps a matter of taste, but I find analytical solutions, as opposed to numerical ones, more enlightening. Unfortunately, the complexity of photosynthesis means that analytical descriptions can only be achieved at the expense of gross simplification . . . [these models] can be useful aids to understanding, and for prediction, but are also potential hazards when the simplifications involved are forgotten.
Graham Farquhar (1989)Creating a computer model for processes as complex as photosynthesis, photorespiration, and dark respiration has proven to be an exceptional challenge. The various feedbacks that are engaged within the processes at specific metabolic steps, and that are triggered by specific sets of conditions, render the numerical modeling framework most applicable. Within the numerical framework, processes can be modeled as a series of sequential biochemical reactions, which can then be integrated across finite time intervals to produce pathway fluxes. While numerical solutions have their advantages, the path to the ultimate outcome tends to be less transparent than the alternative, an analytical solution. Numerical models are seldom amenable to complete mathematical closure, requiring that approximations be made to close the numerical iteration and reach a stable, steady-state, solution. An analytical solution is not constructed from sequential, time-dependent steps, but rather represents a closed set of equations (i.e., no variables left to approximation) that fully accounts for all components of a process or problem. For processes as complex as metabolic pathways, however, analytical solutions are difficult. Thus, even for this approach, researchers have sought approximations and simplifications that must be accommodated in order to achieve a stable, steady-state solution. The danger of relying on such approximations, as stated in the quote above by Graham Farquhar, a noted analyst in the field of photosynthetic modeling, is that these simplifications tend be forgotten and the analytical models migrate with time toward uncritical acceptance.
- Type
- Chapter
- Information
- Terrestrial Biosphere-Atmosphere Fluxes , pp. 89 - 110Publisher: Cambridge University PressPrint publication year: 2014