Plant form analysis based on the pipe model theory I. A statical model within the crown

Extending Oohata and Shinozaki's statical model, a quantitative description of crown/canopy structure is presented. According to this model, the amount of non‐photosynthetic organs in a given horizontal layer can be regarded as supporting the total plant weight above that layer. Within the crown, however, only stems, not branches, support it. In fact, the total amount of a community above a given horizon and the stem density at that horizon are found to be directly proportional, not only in forest stands and glassland communities but also in single trees. This means that the statical model should hold even within the crown/canopy range as well as the leafless range. The present analysis suggests that the crown structure of terrestrial plants is closely correlated with the pattern of branching for optimal use of sunlight. However, linearity of these relationships cannot always be obtained, perhaps due to variation in the branching pattern of trees.