Introduction

Plant canopy structure is the spatial arrangement of the above-ground organs of plants in a plant community. Leaves and other photosynthetic organs on a plant serve both as solar energy collectors and as exchangers for gases. Stems and branches support these exchange surfaces in such a way that radiative and convective exchange can occur in an efficient manner. Canopy structure affects radiative and convective exchange of the plant community, so information about canopy structure is necessary for modelling these processes.

In addition to considering how canopy structure and environment interact to affect the processes occurring in the plant community, the influence of the canopy on the environment should also be considered. The presence and structure of a canopy exert a major influence on the temperature, vapour concentration, and radiation regime in the plant environment. Interception and transmission of precipitation are also affected, as are soil temperature and soil heat flow. Canopy structure can therefore be important in determining the physical environment of other organisms within the plant community, and can strongly influence their success or failure. Plant canopy structure can indirectly affect such processes as photosynthesis, transpiration, cell enlargement, infection by pathogens, growth and multiplication of insects, photomorphogenesis, and competition between species in a plant community. The indirect influence on soil moisture and temperature can also affect root growth, evaporative water losses from the soil, residue decomposition and other soil microbial processes.