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Switzerland’s forests hold more deadwood today than ten years ago. In forests predominantly consisting of beeches and fir trees, the deadwood supply has doubled, in lowland spruce forests, it has even as good as tripled since then.
Subdivided into standing, lying, and total deadwood, the table below lists the mean deadwood supply in cubic meters (m3) per hectare (ha, arithmetic mean) in various types of forests in the 1993/95 and 2004/06 surveying periods with a 95% confidence interval.
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| Forest types |
Cubic meters of deadwood per hectare
1993/95 |
Cubic meters of deadwood per hectare
2004/06 |
| |
total |
Standing |
Lying |
total |
Standing |
Lying |
|
| Highland spruce |
16 ± 2 |
10 ± 1 |
6 ± 1 |
26 ± 3 |
14 ± 2 |
12 ± 2 |
|
| Other coniferous forests |
11 ± 2 |
6 ± 1 |
5 ± 1 |
14 ± 3 |
8 ± 2 |
6 ± 1 |
|
| Fir |
9 ± 2 |
7 ± 2 |
2 ± 1 |
17 ± 4 |
11 ± 3 |
6 ± 2 |
|
| Beech |
8 ± 1 |
6 ± 1 |
2 ± 1 |
18 ± 3 |
11 ± 2 |
7 ± 2 |
|
| Other deciduous forests |
8 ± 2 |
5 ± 1 |
2 ± 1 |
13 ± 3 |
8 ± 2 |
5 ± 2 |
|
| Lowland spruce |
5 ± 1 |
4 ± 1 |
1 ± 0 |
14 ± 4 |
10 ± 3 |
4 ± 1 |
|
| Total |
10 ± 1 |
7 ± 1 |
4 ± 0 |
19 ± 1 |
11 ± 1 |
8 ± 1 |
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Interpretation example
In 1993/95, Swiss beech forests held an average of 6.5 to 9.7 cubic meters of deadwood per hectare, subdivided into 4.8 to 7.2 cubic meters of standing deadwood and 1.3 to 2.9 cubic meters of lying deadwood. In the 2004/06 surveying period, beech forests were found to contain 14.6 to 20.8 cubic meters of deadwood overall (with a likelihood of more than 95%).
Comments
• In the 2004/06 surveying period, all forest types featured distinctly higher deadwood volumes than in the 1990s, with the increase averaging eight cubic meters. Forest types are determined by the predominant tree species.
• Deadwood volumes increased most in highland spruce forests and least in “other coniferous forests”.
• “Other coniferous forests” include tree species such as pine, larch, Swiss stone pine, and the NFI category of “other conifers”. “Other deciduous forests” consist of maple, ash, oak, or chestnut trees and the NFI category of “other broadleaves”.
• The largest supply of deadwood accumulates in highland spruce forests. Such forests are difficult to reach, which quite often makes forestry use hardly worthwhile. Lowland spruce plantations and beech forests, however, hold very small amounts of deadwood.
• In part, deadwood amounts also vary for natural reasons. Not only is decay slowed down or sped up by site factors such as temperature and precipitation, but different tree species decompose at different rates.
• Species diversity is influenced by the way deadwood is distributed in forests. A considerable share of deadwood is found in areas devastated by hurricane Lothar, whereas it is almost absent from others. In other words: means alone cannot adequately describe the situation.
• Data were extracted from the second and third Swiss National Forest Inventories (NFI2 and NFI3), with surveys taken between 1993 and 1995 (NFI2) and between 2004 and 2006 (NFI3).
• The National Forest Inventory differentiates between lowland and highland forests, with the boundary being set at an altitude of 900 to 1,200 meters above sea level depending on growth area, exposition and geology. As a rule, highland spruce forests are subject to natural regeneration, while lowland spruce forests have been planted for economic reasons.
Source
Swiss National Forest Inventory NFI, special analyses of the surveys taken in 1983/85, 1993/95 and 2004/06. 150109UU. Swiss Federal Institute for Forest, Snow and Landscape Research WSL. CH-8903 Birmensdorf.
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