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Components of the SIMO framework

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This documentation includes the description of SIMO framework. It’s meant to give a general overview of the structure and use of the framework for the users and developers.

During the fall of 2004 the department of Forest Resource Management at the University of Helsinki embarked on a joint project together with Metsähallitus, Forestry Centres and Forestry Development Centre Tapio, Metsämannut Oy, Tornator Oy and UPM-Kymmene Oyj to raise the level of forest management planning in Finland as well as to improve the compatibility of planning systems. The project was given the name SIMO, as SIMulation is used to produce alternative scenarios for forest management and Optimization is used to choose the one matching the goals for planning the best.

The goals for the project weren’t too modest:

The system should be flexible with regards to the data and models used.
It should be adaptable to different planning problems and extendable
to cover the future planning needs.

Hence, during the development attention was paid to enable use of data sources of varying content in the planning. Analysis of the suitable application domain for each model should reduce the errors in the planning results. The awareness of the users of these errors is raised by including a mechanism that warns the user when models are used outside their domain. The usability of models is extended by including a flexible mechanism for level correction.

Special attention has been paid to the matching of the planning data properties and the characteristics of the models used to process the data. In the documentation you’ll frequently come across the term ‘model chain’. It refers to a set of actions in which individual models are applied to the data to get the prediction of the value of the attribute under interest. One example of a model chain in a individual tree level simulator would be a sequence of models to predict the survival probability of trees; mortality due to competition, mortality due to aging, and the total mortality.

The simulations in SIMO are collections of these model chains. This is the key to the flexible assembly of different simulators that all utilize the SIMO framework.