The core of the EFISCEN model was developed in the late 1980s for Sweden by Prof. Ola Sallnäs at the Swedish Agricultural University. The first European application of this model was carried out by the International Institute for Applied Systems Analysis (IIASA) in the early 1990s. This application was motivated by the expectation of large-scale dieback due to acidification. The model was transferred to EFI in 1996, and given the name EFISCEN (version 1.0). At the same time, the underlying EFISCEN inventory database was updated and further expanded with the help of many country correspondents and inventory experts.
By the year 2000, several changes were made to the model, resulting in EFISCEN version 2.0. The changes were:
- The decline module as used in the IIASA study was taken out of the model code.
- The width of the age classes during simulations was set equal to the time step of the model (5 years).
- The possibility was introduced to change the tree species after final harvest.
- The way thinnings are handled in the model was changed, by introducing a growth boost and modifying the transition of area between matrix cells.
- An option was built in to be able to change the transition chances over time, for example due to climate change.
- A biomass carbon module was added to estimate carbon stored in whole tree biomass with help of biomass expansion factors.
- A products module was developed to track carbon stored in wood products
- A soil module (the YASSO soil model) was added to calculate carbon stocks in forest soils.
Soon after these improvements, work started at EFI to reprogram EFISCEN from Fortran to C++ (EFISCEN 3.x). Several sub-versions of the model have been developed and the most recent version is EFISCEN 3.1.3.
In 2011 another process was started to re-implement EFISCEN from C++ to Java to improve EFISCEN with participation by the University of Eastern Finland and Alterra. Besides re-implementation, model functionality has been extended as well. All steps were completed in summer 2014. The re-implemented EFISCEN is named version 4.1. Key improvements in EFISCEN 4.1 as compared to EFISCEN 3.1.3 are:
- Graphical User Interface (GUI) has been redesigned with additional functionality. Total and selected data is now divided to two tabs to make the interface less crowded.
- In the GUI, the user can now select multiple regions, owners, sites or species in the selection tree and data are shown in the selected-tab accordingly.
- All simulation values that are shown in the panels can also be shown in the graphs with their history. Variables to show as graphs can now be easily toggled by clicking corresponding buttons.
- Error messages have been made more descriptive and log files are now provided that describe any possible errors.
- Time step specification in scenario files has been changed so the last parameter values are used when the last step in scenario file is reached, rather than re-running the whole scenario.
- Area scaling factors can now be applied to individual matrices through a newly added scenario file.
- Management parameters that were previously fixed through the simulation can now change. They are defined in two new scenario files. This feature allows the user to modify management regimes along the course of the simulation.
- Scenario file format has been extended to include individual matrix scaling and thinning and felling change files.
- All output files are now written in .csv format
- It is possible for the user to specify a list of output files that need to be created
In addition to the re-implementation and adding more options for creating scenarios, another feature that has been added is that EFISCEN outputs can directly be saved to an external database. Databases that are currently supported are MySQL, PostgreSQL and Microsoft Access.