ABSTRACT
This chapter presents a class of photosynthesis models that scale up from single-leaf estimates to the whole plant and entire canopies. Single-leaf photosynthesis is the basic unit of canopy photosynthesis models, and carbon assimilation for this basic unit depends on photosynthetic characteristics and surrounding microclimatic conditions. Whole-plant/canopy photosynthesis is accomplished by simultaneously calculating single- leaf fluxes at multiple locations within the plant canopy. A simple situation arises when one species overtops another, but the typical canopy has foliage elements mixed within canopy layers. Canopy photosynthesis models may also be reduced in complexity particularly with research directed at landscape level fluxes. Diffuse radiation reflected and transmitted by foliage is difficult to accurately portray in canopy models. Individual plants within the canopy are fitted to concentric cylinders and horizontal layers of relatively uniform foliage density and orientation. Primary productivity of a whole plant or canopy is the cumulative carbon gain from all photosynthetically active organs.
