Digital Design of Nature

Architectural Analysis of Trees

The concepts described so far are the decisive factors for the general construc­tion of branching structures. However, the vast variety of trees found in nature, necessitates a more detailed categorization that takes into account architectural principles, and which at the same time analyzes the type of branching and the influence of the above mentioned factors with regards to the different orders of branching structures.

Halle, Oldeman and Tomlinson in their fundamental work “Tropical Trees and Forests, an Architectural Analysis” [81] divide tropical trees into 23 architec­tural models and one theoretical extension based upon their branching structure and other parameters.1

This approach is significant, as non-tropical trees can also be placed within this model. The classification plays an important role with respect to the syn­thetic creation of plants. To classify a plant, a decision table is used [81]; the corresponding images are found in Fig. 2.5. [1]

Chapter 2 The individual categories are named after botanists who studied tropical plants. Plants A variety of single plants with quite different looks can be assigned to a cate­

gory. Nevertheless, it is surprising that 23 categories are sufficient to describe the vast variety of species in a tropical tree forest.

theoretical Roux

Figure 2.5 The classification is mainly based on the existence and/or absence of sympodial Tree architecture models horn [81] growth, the branching characteristics, whether growth takes place or not, and

on the type of tropism.

For example, in Corner’s model only the primary axis exists, but no branching. These plants are monopodials. A typical representative of this species is the coconut palm. In the Leeuwenberg model the buds die off within one year, which results in a typical sympodial structure.

In Massart’s model, the primary axis is orthotropical (grows vertically), all other axes are plagiotropical. The plant itself is a monopode with rhythmic branching patterns; examples are conifers such as spruces and pine trees. In Rauh’s model, only plagiotropic axes are found. These trees are also monopods

with rhythmic branching patterns. Prominent examples are different types of spruces.

Aside from the value of this categorization method for botanists, the architec­tural analysis helps to determine the characteristics of a computer model which would allow reproduction of as many plants as possible. The view of the trees in this kind of refinement shows for example that a purely recursive computer program, which applies the same mechanisms to each branching level, cannot produce the vast variety of botanical trees. Though for many trees of the North­ern Hemisphere which show a comparatively regular structural pattern this is still an acceptable method, it is not effective for tropical trees. Nevertheless, re­cursive tree production algorithms are currently still being implemented, which results in relatively inadequate results.