Main species
Swedish
Contents
To determine the main crop species (represented by ForestData.RegenerationSpecies) for a stand based on a certain forest state is not as trivial as one may think. A very large number of birch plants in a spruce plantation does not mean that birch is the intended crop species.
The main species is an important variable in Heureka since it is used in treatment models:
| • | When determining Minimum Final Felling Age. |
| • | In precommercial thinning (cleaning) adn thinning to determine which species to retain as default. |
In Heureka the main species is determined in the following way:
| 1. | If the regeneration species is known, the main species is set to that. The regeneration species is known if you have set to Regeneration Species field to a value when importing a stand register, or if the stand has been regenerated by Heureka regeneration model. If you want to make sure that an oak stand is cleaned and thinned so that the oak trees are retained as a first choice, you should set the Regeneration Species in the stand register to the species group code for oak. |
| 2. | If there is no information in the input data of what the regeneration species is, and it is a young stand, the stem distribution is used to determine it. A sufficient criteria to be classified as a conifer stand, is that the expected number of main crop trees are conifer trees is at least 800 per ha (this is a setting you can modify in control table Treatment Model, via parameter Conifer Criteria). Another sufficient criteria is that at least 50 % of the stems are expected to be main crop trees, according to crop tree probability functions used in Heureka (by Björn Elfving). If any of these criteria are met the conifers species with largest number of main crop trees is set as main species. |
| 3. | If there is no information on what the regeneration species in an established stand, the volume distribution per species is used to determine the main species. overstorey trees are excluded. A sufficient criteria to be classified as a conifer stand, is that at least 50 % of the stem volume are from conifer trees. In that case the conifers species with the largest volume is set as main species. |
In Heureka there is number of other variables that are closely related to ForestData.RegenerationSpecies
SiteIndexSpecies Species for which the site index refers to. If another species than pine or spruce is used in the input data, it is converted to either pine or spruce according to Lantmäteriet site index conversion system.
DominantSpecies: Dominant species as calculated according to case 2 or 3 above, that is DominantSpecies is the same as RegenerationSpecies if case 2 or 3 applies, but may differ if case 1
TreatmentData.RegenerationSpecies: Actual regeneration species used when simulating a new generation. ForestData.RegenerationSpecies is assigned the same value if a stand has been regenerated by Heureka.