| Table 1. Description of the most relevant stand variables and description of the variables used for assessing forest damage at the stand level in the 8th–10th National Forest Inventories (NFI) of Finland 1986–2004. The numbers (8,9,0) after the damage codes refer to the NFIs (10th NFI expressed as 0). For a more detailed description, see Tomppo et al. 2011. | ||
| Variable | Description | Codes |
| Land use class | Land use form from the standpoint of forestry | 1 Forest land: stocked or temporarily unstocked land with potential capacity to produce a mean annual increment of at least 1 m3 of stem wood over bark over the prescribed rotation under the most favourable stock conditions. Parks and yards are excluded. |
| Main tree species | The most frequent species (by volume) in the dominant tree storey of the stand. Also called dominant species. | Names of 12 coniferous and 17 deciduous tree species. Four or seven classes were used in our analysis to describe both the main (dominant) species and the mixed species in a stand. The seven classes were as follows: 1) Scots pine 2) Norway spruce 3) birches 4) aspen 5) alders 6) rowan 7) others, the four-class classification combined 4–7 into 4. |
| Principal site class | Divides forest, scrub and waste land into mineral soil and main peatland classes. A site is classified as peatland if the organic layer is peat or if more than 75% of the ground vegetation is peatland vegetation. Otherwise, the site is mineral soil. |
1 Forest on mineral soil
2 Spruce mires 3 Pine mires 4 Treeless peatland (open bogs and fens) |
| Site type | Site fertility class |
1 Herb rich sites, eutrophic mires and fens and corresponding drained peatlands
2 Herb rich heath forests, mesotrophic mires and fens and corresponding drained peatland forests 3 Mesic forests on mineral soil and meso-oligotrophic natural and drained peatlands 4 Sub-xeric forests on mineral and oligotrophic natural and drained peatlands 5 Xeric forests on mineral soil and oligo-ombrotrophic natural and drained peatlands 6 Barren forests on mineral soil and Sphagnum fuscum dominated (ombrotrophic) natural and drained peatlands 7 Rocky and sandy soils and salt marsh (alluvial lands) (combined with class 6 in the analysis) 8 Summit and fell forests (combined with class 6 in the analysis) |
| Drainage stage | Possible drainage and its effects on vegetation and forest yield (progress of the drainage effect) |
0 undrained
1 drained mineral site 2 recently drained peatland: the drainage effect cannot yet be observed in ground vegetation and only slightly in growth of trees 3 transforming drained peatland: the drainage effect is clearly visible although the ground vegetation is still characterized by the original peatland type 4 transformed drained peatland: drainage has resulted in the appearance of some mineral soil under the vegetation. Water relations do not prevent closure of the canopy |
| Regeneration method of the stand | Definition is based on the amount and location of seedling material |
1 natural regeneration, or open area without man-made regeneration
2 artificial regeneration, failed 3 artificial regeneration, successful 4 artificial regeneration, succeeded after replanting 5–8 as 1–4, but codes used for afforested fields |
| Silvicultural quality of the stand | The division is based on species composition, dominant height, even spatial distribution, density and technical quality of the dominant tree storey |
1 good
2 satisfactory 3 adequate 4 low-productive: the yield is so low that the stand should be regenerated before maturity |
| Development class of the stand | The maturity class of the stand as defined using the height and the diameter (at breast height) of the dominant trees |
1 Temporarily unstocked regeneration stand: a treeless area with possible retention trees. Small groups of seedlings may also occur on stands belonging to this class.
2 Young seedling stand: a stand with a dominant height of the dominant tree species less than 1.3 m. 3 Advanced seedling stand: a stand with a dominant height of the dominant tree species of more than 1.3 m. For a major part of the dominant trees the diameter at breast height must be less than 8 cm, and for the largest trees, less than 10 cm. The mean age (at breast height) of the dominant trees should not be more than 50 years in South Finland and not more than 120 years in North Finland. 4 Young thinning stand: a stand with a young growing stock at the thinning cuttings stage. The major part of cutting removal should be pulp wood-sized. The minimum mean age (at breast height) is 11 years and maximum 120 years in South Finland and 200 years in North Finland. 5 Advanced thinning stand: a stand with an older growing stock and a larger pole size than in young thinning stand. Saw-timber sized stems are typical and also the thinning removal typically contains saw timber. The minimum mean age (at breast height) is 20 years and maximum 140 years in South Finland and 200 years in North Finland. 6 Mature stand: a stand with a growing stock either old and/or large enough for the goal. Of the management of the stand to be regeneration cutting and establishment of a new stand but regeneration cutting had not yet been started. The maturity for regeneration was primarily determined with the help of the age of growing stock, and to some extent with the help of mean diameter. 7 Shelter tree stand: a natural regeneration area, usually with 150–300 stems per hectare. The density and structure of the seeding trees allowed natural regeneration. The regeneration may also call for planting or seeding. 8 Seed tree stand: a natural regeneration area usually with 30–150 fairly large seed trees per hectare (the minimum for birch is 10–30). A guiding maximum basal area for a seed tree stand after cutting was 5 m2/ha. |
| Soil preparation measures | Soil preparation measures accomplished most recently (within 30 years) | 0 None 1 Harrowing 2 Scarification 3 Ploughing 4 Mounding 5 Mounding and ditching 6 Prescribed burning |
| Proposed cleaning or thinning | The cutting proposal for the next 10-year period (by the leader of the inventory team)(11 codes) | 0 No proposal 1 Thinning or cleaning of the stand 2 First commercial thinning 3 etc. |
| Damage symptom | Visual outlook of the injury | 0 no damage 890 1 dead standing trees 890 2 fallen tree or standing stem(s broken below the crown 890 3 decayed standing trees 890 4 stem or root damage within 1 m from the stem 890 5 resin flow (above 1,5 m in stem) 90 6 broken or dry top (in the upper half of the crown) 890 7 other crown malformations 890 8 technical defects on stem 90 9 dead or broken large branches 90 A unnaturally pruned branches (from below ) 90 B defoliation 890 C discolouration 890 D multiple symptoms due to ageing 89 |
| Degree of damage | Apparent severity of damage (at the stand level this is the summed importance of all damage causes ) | 0 slight damage, symptoms observed, but the damage does not reduce the silvicultural quality of the stand 890 1 moderate, the stand quality is reduced by one class 890 2 severe, the stand quality is reduced by more than one class 890 3 complete, artificial regeneration is required 890 |
| Age of damage | The time when the damage has started and the possible continuing effect of the cause in the stand | 0 started less than two years ago 90 1 started 2–5 years ago and still continuing 90 2 started 2–5 years ago, but ceased 90 3 started more than 5 years ago and still continuing 90 4 started more than 5 years ago but ceased 90 |