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> Forest Report 2015 Condition and Use of Swiss Forests FOEN / WSL 2015
3.1 Timber use and increment
Christoph Fischer, Paolo Camin
> The growing stock in the Swiss forest is increasing since the net increment is higher than the amount of timber used annually.
> In Switzerland, an average of 8 million cubic metres of new wood grows every year. Spruce and beech make up more than half of this increment.
> Conifer wood is used more than three times as much as broadleaf wood.
> On the Swiss Plateau, the use of spruce is intensive and exceeds its net increment. In the Alps and the Pre-Alps, spruce is being used less and its net increment exceeds its use.
Use and increment
The wood from Swiss forests has been used more and more in the last 30 years or longer. Between the National Forest Inventories 1983/85 and 1993/95, the annual use of wood was 5.4 million cubic metres (Brassel and Brändli 1999). Today (NFI 1993/95 to NFI 2009/13) it is 7.3 million cubic metres annually. However, the regional differences are large: the forest on the Swiss Plateau is being used most intensively (Fig. 3.1.1), the forest in the Jura, in the Pre-Alps and in the Alps less and that on the Southern slopes of the Alps least.
Almost three times more conifer wood is used than broadleaf wood (Fig. 3.1.2).
According to the National Forest Inventories 1993/95 and 2009/13, the wood increment has remained almost the same. The inventories distinguish between the gross and net increments: the gross increment measures the wood incre- ment of both living and dead trees, while the net increment measures only that of the living trees. The gross increment in Switzerland is 9.9 million cubic metres of wood per year, which is equivalent to 9 cubic metres per hectare per year (m3/ha/year). This means that, in comparison to other European countries, Switzerland has the most increment (Forest Europe et al. 2011). The net increment is decisive for the development of growing stock and provides an impor- tant parameter for comparison with use. In Switzerland, the average annual net increment is 8,1 million cubic metres, or 7.4 m3/ha/y.
The regional differences are considerable. The net incre- ment is highest on the Swiss Plateau, where there are nutri- ent-rich soils (Fig. 3.1.1), but closer to the Swiss average in the Jura and Pre-Alps. In the Alps and on the Southern slopes of the Alps, the annual net increment is, in comparison, signifi- cantly lower than in the other regions.
Conifers contribute 4.9 m3/ha to the annual net increment and thus almost twice as much as broadleaf trees, for which the increment is 2.4 m3/ha. More than half of the annual net increment is accounted for by only two tree species: spruce (3.1 m3/ha) and beech (1.4 m3/ha; Brändli et al. 2015).
Use in comparison to increment
An important indicator for judging the sustainability of forest management is the comparison between the wood increment and wood use. Forest management can be considered sustain- able if the use and the increment are in equilibrium in the long term.
The annual net increment in the Swiss forest is 7.4 m3/ha, which exceeds the annually used amount of 6.6 m3/ha. For-
Fig. 3.1.1 Use and net increment of wood between 1993 and 2013 in the 5 production areas in Switzerland. Source: NFI
7.5 7.3
7.3 8.6
2.7 5.1
1.0 4.2 13.8 11.5
Timber harvesting (m3/ha and year) Net increment (m3/ha and year) Switzerland: Timber harvesting 6.6 m3/ha and year;
Net increment 7.4 m3/ha and year
> 3 Use 3.1 Timber use and increment 61
est management activities therefore do not fully exploit the annual net increment and the growing stock is increasing (section 1.2). An important reason for this is that access to the resource wood is difficult in some regions. The access infrastructure in the forest in mountainous areas is poor, and the cost of wood harvesting there is consequently high.
Other important reasons why the sustainable wood poten- tially available is not all used everywhere include the way organisational structures tend to cover only small areas, the low prices for wood, the requirements of the public, ecolog- ical restrictions in, for example, reserves, the promotion of biodiversity and the preservation of the landscape area. The regional differences here are also large: on the Swiss Plateau, up to 122.6 per cent of the net increment is being used, but on the Southern slopes of the Alps only up to 20.4 per cent. And there are also differences in the types of trees: on the Swiss Plateau 3.2 m3/ha more spruce is felled every year than grows.
This has led to a decrease in the spruce stocks on the Swiss Plateau (section 1.2).
In comparison to other European countries, the Swiss forest has a large growing stock (section 1.2). The amount of wood used can be above the net increment regionally and over short periods of time without endangering sustain- ability. A study on the wood use potential in Switzerland (Hofer et al. 2011) developed several usage scenarios and explored their consequences for forest management for the period 2016 to 2026. The study shows that 7.5 to 9 million cubic metres of wood can be felled annually without endan- gering sustainability. Harvesting can even be increased for short periods to 10 million cubic metres per year (these values are not, however, directly comparable to the NFI results). It is
an aim of the federal forest policy to increase the annual use of wood to 8.2 million cubic metres by 2020.
Fig. 3.1.2 Timber use in Switzerland according to the main tree species. Source: Holznutzung NFI 2009/13
0 500 1,000 1,500 2,000 2,500 3,000 4,000
Timber harvesting (1,000 m3/year)
Spruce Silver fir
Pine Larch
Swiss stone pine Other conifers
Beech
Maple Ash Oak
Chestnut
Other broadleaf trees
