Finnish Forest Research Institute  Metla

Media release 23.11.2005

A computer model for research and visualisation of tree growth

During the past ten years increased computing capacity and the development of programming tools have significantly enhanced possibilities to explore the architecture and physiological functions of trees through detailed modelling, i.e. using computer programs. LIGNUM, a computer model developed by researchers of The Finnish Forest Research Institute (Metla) and the University of Helsinki visualises individual shoot apexes, leaves and buds as grouped architecture in three dimensions. Furthermore, the essential physiological functions are executed in these structural elements. When the detailed description of the structure is entered into the computer, the program can produce real-looking images of trees on screen. The new model differs from earlier ones in that it contains everything in the same package: the detailed structure, physiological functions and visualisation – in fact, a virtual tree. The model is among the first of its kind.

A new feature was recently added to the LIGNUM model for visualising the architecture of trees and plants as well as its development by using a simple description language. It facilitates the visualisation of various canopies. Similar tools are used in computer-made animated films. The adventures of Shrek, for instance, take place in digital forests made using similar methods.

The basic idea in LIGNUM, combining the description of the tree structure and function into a single model, has been shown to be fruitful. It has been applied to studying growth reactions in understory seedlings, remote sensing applications, analyses of canopy light environment, and visualisation of tree rot in city trees.

A lively national and international collaboration has developed around the LIGNUM model, and LIGNUM is being developed in conjunction with several research projects. Among the currently ongoing projects are: competition between trees in mixed forests in Finland (www.metla.fi/projects/sscs) and Canada (www.unites.uqam.ca/gref/projetsa.html) funded by the Academy of Finland; visualisation of tree rot and decay in trees in Finnish cities and assessment of the risk of falling; poplar research in short rotation forestry in the USA (www.missouri.edu/~mln52/PoplarResearchForMiaoerLu/), and interdependence between seed yield and height growth of Stone pine (Pinus pinea L.). LIGNUM's possibilities for visualisation are also being utilised for the forest educational programme (www.joensuu.fi/ktl/saima/pume2_projekti.htm).

LIGNUM is programmed in the C++ language and it is available, upon request, for Unix, Linux and Mac platforms (partly Windows as well).

The development work for the LIGNUM model is part of Metla’s research programme “Alternatives for silvicultural practices in forest management and their effects on forest production", scheduled to be completed in 2006.

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