Tree growth and architecture

Some useful concepts of plant architecture

Architectural model

Plant development appears to follow a particular pattern which can be characterized by the combination of very few characters (type of growth, of branching, flowering location, axis differentiation). The possible combinations observed actually are about 23, each particular combination constitutes an architectural plant model, each covering a large number of species and dedicated to a botanist (i.e. Rauh's model , Massart's model ). A plant species then conforms to a particular architectural model, which means that plant body edification follows precise development rules.

Architectural unit

The architectural model concept was too large and synthetic to be pragmatically useful in field to approach species specificity. So next architectural analyses have focused on particular traits of each type of axes elaborated during plant development. So distinction could be made between the stem (trunk) and other axes, and so on for each set of axes exhibiting specific features on young trees. Thus a schematic representation of the plant body could be made, describing in a table all the distinctive traits of the categories we made within the tree architecture. This set of information (schema and table ) constitutes the architectural unit (Edelin, 1977, Barthélémy et al., 1991 ).

Reiteration process

During its development, a plant becomes bigger and bigger. This increase in size of the plant body is often possible by a duplication of the existing architecture. This phenomenon first described on big forester tree was called reiteration by Oldeman (1974) . Reiteration allows trees to optimize space occupancy according to available energy.

Architectural sequence

The set of architectures exhibited during all the tree life span can be summarized as the main step of stem and crown edification .