Background
Version 22.8.0 of the MOTTI simulation kernel, maintained and developed by the Natural Resources Institute Finland (Luke), has been used in IPTIM planning calculations since last autumn. Since then, the growth models in the simulation kernel have been further developed and errors detected have been corrected. The IPTIM planning system is in the process of migrating to the newer MOTTI version (22.8.3). For this change, the differences between the versions were investigated and examined by calculating simple designs in IPTIM for the test material under both the current and the new MOTTI versions.
The data used for the comparison was forest resource data, which included samples from different geographical areas, habitats and development classes. The area of forest land included in the analysis was slightly less than 20 000 ha.
Continuous development of the MOTTI simulation kernel
Luke publishes corrections and updates to MOTTI, for example as new NFI results are completed. At AFRY, we closely monitor model changes and update new versions as needed. We aim to update the models outside of the busiest valuation seasons. A comprehensive round of testing always precedes the update of models, and the results are reported before the introduction of new models. However, updates will need to be introduced to address any errors identified and to provide the latest growth projections.
Results
Differences in tree identifiers between MOTTI versions are mostly small. The most significant difference between the versions is in peat soils, where volumes are somewhat lower in the new version (22.8.3) than in the current version (22.8.0). In the calculation data, the current volume of peatlands calculated with the new version of MOTTI is about 2.0% (about 2.8 m3/ha) lower than with the current version in ears and about 1.4% (about 1.7 m3/ha) lower in bogs.
Differences between MOTTI versions were calculated for each geographical area (8) and for the whole dataset. The relative change for each variable considered was calculated by comparing how much higher or lower the variable value is with the new MOTTI version (22.8.3) than with the current version (22.8.0).
| S-Ostrobothnia | S-Finland | Kainuu-Koillismaa | M-Finland | Kymi-Savo | Lapland | N-Ostrobothnia | Savo-Karjala | Entire dataset | |
| I | 1.5 | 0.5 | 0.2 | 1.1 | -0.2 | 0.8 | |||
| II | 0.7 | 0.6 | 0.5 | 0.2 | 0.4 | -0.69 | -0.1 | 0.6 | 0.6 |
| III | -2.5 | 0.5 | 0.1 | -0.02 | 0.5 | 0.14 | 0.7 | -0.02 | 0.3 |
| IV | 0.1 | 0.3 | -0.08 | 0.02 | 0.4 | 0.5 | -0.3 | -0.0006 | 0.2 |
| V | 0.09 | 0.4 | 0.009 | -0.4 | 0.3 | -0.3 | -0.1 | 0.1 | 0.2 |
| VI | -1.1 | -0.04 | 2.4 | 2.4 | 0.4 | 2.2 | 2.1 | 0.3 | |
| Mire | -9.6 | -2.6 | -0.5 | -1.6 | -2.3 | -0.8 | -4.1 | -1.6 | -2 |
| Bog | -1.0 | -1.5 | -1.3 | -0.9 | -2.6 | -0.7 | -1 | -0.8 | -1.4 |
| TOTAL | -0.6 | 0.3 | -0.4 | -0.3 | 0.1 | 0.03 | -0.2 | -0.1 | 0.01 |
Table 1. Change in current stock by site index and geographic region, %.
| I | II | III | IV | V | VI | Mire | Bog | TOTAL |
| 1.8 | 1.1 | 0.45 | 0.29 | 0.23 | 0.3 | -2.8 | -1.7 | 0.02 |
Table 2. Change in current volume by site index in the entire dataset, m3/ha.
| S-Ostrobothnia | S-Finland | Kainuu-Koillismaa | M-Finland | Kymi-Savo | Lapland | N-Ostrobothnia | Savo-Karjala | Entire dataset | |
| I | 1.1 | -0.3 | 1.1 | -0.3 | -0.8 | 0.7 | |||
| II | 0.4 | 0.9 | 0.4 | 0.5 | 0.4 | 0.1 | -0.4 | 1.8 | 0.9 |
| III | 0.1 | 1.1 | 0.8 | 1.0 | 0.4 | 0 | 1.9 | -0.3 | 0.6 |
| IV | 0.6 | 0.9 | 0.6 | 0.6 | 0.5 | -0.1 | -0.2 | 0.4 | 0.5 |
| V | 1.5 | 0.3 | 0.6 | 1.3 | 0.8 | 0.4 | 0.1 | 0.7 | 0.7 |
| VI | 2.6 | 0.1 | 5.0 | 1.5 | 44 | 1.0 | 0.5 | ||
| Min. soil total | 0.5 | 1.0 | 0.7 | 0.8 | 0.5 | -0.1 | 0.7 | 0.2 | 0.6 |
| Mire | -3.5 | -1.2 | 1.0 | -0.5 | -0.6 | -1.0 | -4.1 | -0.7 | -0.9 |
| Bog | -0.5 | -1.0 | -0.5 | -0.3 | -1.3 | 0 | -0.5 | 0.1 | -0.6 |
| TOTAL | 0.3 | 0.8 | 0.3 | 0.6 | 0.3 | -0.1 | 0.2 | 0.1 | 0.4 |
Table 3. Change in Current annual increment by site index (%).
| I | II | III | IV | V | VI | Mineral soil total | Mire | Bog | TOTAL |
| 0.06 | 0.08 | 0.05 | 0.02 | 0.03 | 0.01 | 0.04 | -0.06 | -0.1 | 0.02 |
Table 4. Change in Current annual increment by site index in the entire dataset, m3/ha/a.
Comments
0 comments
Please sign in to leave a comment.