Eero Nikinmaa

Structural Regularities in Trees

Several processes, such as photosynthesis and water and nutrient uptake, are simultaneously running in plants. Fluxes of processed products, such as sugars, water and nutrient ions connect the processes with each other. Highly specialised structures have developed in evolution for each process and transport phenomenon. According to the basic idea 7 of the cover theory ( Chap. 2), these structures are effective, and basic idea 9 says that the biochemical regulation systems play an important role in the formation of the structures. The water transport within trees generates regularities in the structure of woody components.

Invited Talk: Functional Structural Plant Models - Case LIGNUM

The functional structural plant models (FSPMs) can be defined as models that combine descriptions of metabolic (physiological) processes with a presentation of the 3D structure of a plant. They contain usually the following components 1) Presentation of the plant structure in terms of basic units, 2) Rules of morphological development and 3) Models of metabolic processes that drive the plant growth. The main emphasis in these applications has been individual plants. It is understandable because, due to the detailed description of the plant structure, and consequently, of the local environment of each organ, the FSPMs tend to require a large number of parameters and/or input data. Owing to the large amount of information they contain about the plant to be modeled, they also tend to be computationally heavy. In the following we shortly describe how the three FSPM model components have been realized in the LIGNUM model. Three basic units (Tree segment, Branching point and Bud) are used. We are using the STL template library of C++ to define a blueprint of a tree that can be instantiated by actual representations of the species specific components. We are using four generic algorithms for traversing the data structure of the tree and to make calculations. L-systems are used for specifying the morphological development of the trees. We present three examples of applications made using LIGNUM: a calculation of optimal leaf traits in Sugar maple saplings, a system for storing and analyzing information on decay in city trees and simulation of growth of a tree stand.