9th National Forest Inventory (NFI9)
Sampling design
In the NFI9, systematic cluster sampling was applied. Because of the variation in forest structure and density, the sampling design varied in different parts of Finland. In the planning of the design, sampling error and costs, i.e. resources available, were taken into account. For efficiency, the size of clusters, i.e. the number of sample plots and the distance between them, was planned in such a way that they could be measured in one working day.
One fifth of the sample plots was established as permanent plots, and they will be remeasured during the on-going NFI10. Permanent sample plots were placed in every fourth cluster.
Sampling designs areas and their parameters
| Area |
Distance between clusters |
Shape of a cluster |
Distance between plots within a cluster |
Number of plots in a temporary (permanent) cluster |
| Åland |
6 x 6 km 1) |
L-shaped |
250 m |
14 (10) |
| Southernmost Finland |
6 x 6 km |
L-shaped |
250 m |
14 (10) |
| Central Finland |
7 x 7 km |
Rectangular |
300 m |
18 (14) |
| Southern North Finland |
7 x 7 km |
L-shaped |
300 m |
15 (11) |
| Lapland |
10 x 10 km |
L-shaped |
300 m |
15 (11) |
| Nothern Lapland |
- 2) |
L-shaped |
450 m |
9 (9) |
1) The sampling was densified by a double amount of temporary clusters.
2) Stratified sampling: sampled area was first divided into 6 strata according to the percentage of forests. Stratification was based on the forest maps produced by the multi-source NFI using satellite imagery and NFI8 data.
Map of sampling designs
You can have a look on the design of the area by clicking on the map.
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