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> Forest Report 2015 Condition and Use of Swiss Forests FOEN / WSL 2015
4.7 Forests in the landscape
Christian Ginzler, Felix Kienast
> Forests in Switzerland have been spreading in the Alps for decades, and the trend is continuing.
> The pattern of the forest is also changing as small patches of forest merge. This leads to the loss of sparse and structure-rich habitats, as well as of recreation areas for people.
> The increase in forest area does, however, improve the forest’s protection service.
> Disturbances like the windstorm ‘Lothar’ create open areas, but generally existing forest areas are becoming denser and darker.
Forest patterns
Nearly a third of Switzerland’s surface area is covered with forests. They form patterns in the landscape that have devel- oped through their large-scale distribution and the small-scale configuration of individual forest areas. These forest patterns have been substantially shaped by humans. For many cen- turies, human activities have been leaving their mark on the distribution of the forest through clearing it long ago, build- ing settlements and roads, as well as agriculture and forestry.
The forest patterns thus reflect the cultural inheritance of the region. For example, the forests in the Alps have been spread- ing for several decades at the cost of open landscape. This is changing forest patterns in many places.
The aerial photos taken for the land-use statistics indi- cate that the woodlands (groups of trees and hedges) outside the forest shrunk by 2 to 7 per cent, depending on the region, between the surveys in 1992/97 and 2004/09 as a result of clearances on agricultural land and widespread building. The development varies from region to region, but has been par- ticularly pronounced on the Swiss Plateau. The forests there have become an important refuge area for many animal and plant species because suitable habitats in the open landscape are increasingly lacking. According to the National Forest Inventory NFI 2009/13, the forest area has grown further. The regional differences are large. It has remained unchanged on the Swiss Plateau, but increased by a few per cent in the Jura and in the Pre-Alps, and by as much as 13 per cent in some places in the Alps and on the Southern slopes of the Alps (section 1.1; Table 4.7.1). The area pattern of the forest, which consists of numerous patches of forest, has also changed. The number of forest patches has remained constant in the Jura and on the Swiss Plateau, and in the Pre-Alps only a few forest patches have merged. In the Alps and on the Southern slopes of the Alps, however, many patches of forest have amalga-
mated, and numerous gaps and clearings have thus become overgrown and closed.
How people experience the landscape is influenced by how much the forest has ingrown. Most find half-open forest landscapes in medium stages of reversion to forest more attrac- tive than closed homogeneous forests (Hunziker et al. 2012).
Dense continuous forests, however, provide better protection against avalanches and rockfall (section 5.2), and more effec- tive connectivity for many forest species (section 4.1). More- over, large and dense forests safeguard the good quality of the drinking water because forest soils are rich in humus and roots and thus an optimal water filter (section 5.1). Forest patterns therefore have numerous ecological, social and economic effects. This is why the implementations of the Forest Devel-
Fig. 4.7.1 Wooded pasture with sycamore on the Chasseral (BE) – an attractive landscape with many forms of use.
Photo: Markus Bolliger
> 4 Biodiversity 4.7 Forests in the landscape 85
opment Plans (Waldentwicklungspläne WEP) (section 3.4) and Landscape Development Schemes (Landschaftsentwick- lungskonzepte LEK) are important instruments to help har- monise the various functions of the forest.
Forest edges and light availability
Comparing the development of the forest area and the num- ber of patches of forest (Table 4.7.1) indicates that everywhere where the forest area has greatly increased, the number of individual forest patches has decreased. As a consequence, ecologically valuable forest edges, which provided habitats for numerous animal and plant species, have disappeared. Since 1997, this development has slowed as, by that point in time, many patches of forest had already grown together. What is gratifying is that, during the past 20 years, the width of forest edges has increased, particularly at higher altitudes. The width of the shrub belt has stayed more or less constant, while that of the herb fringe has slightly increased. A shrub-belt width of 5 to 10 metres is optimal for species diversity. According to the NFI 2009/13, only around 16 per cent of the 170,000 kilo-
metres of forest edge have an optimal width. On the Swiss Plateau and in the Jura and Pre-Alps, the width of most forest edges is less.
The availability of light in the forest has slightly de- creased since 2000. The stand density has increased, particu- larly in the Alps and on the Southern slopes of the Alps (sec- tion 1.3). Sparse stockings close gradually. Open areas have been created, especially at lower altitudes, as a result of the damage to the forest and the intensified use of wood after the windstorm ‘Lothar’, the hot summer of 2003 and regional events.
Wooded pastures and orchards
Chestnut orchards and wooded pastures are two typical exam- ples of culturally influenced forest patterns that developed his- torically (Fig. 4.7.1). According to Switzerland’s Forest Act, they are part of the forested area, providing a diverse habitat for many species, with a varying mixture of grazing land, sin- gle trees, groups of trees and small patches of forest. Chestnut forests make up 0.13 per cent, i.e. just a small part of Switzer- land’s forest area.
Wooded pastures were originally present in many mountain regions, but today they are mostly found in the Jura (Table 4.7.2). They are maintained through the grazing of horses and cattle, which graze not only on the open pastures but also in the forested parts, where they eat the seedlings of young trees and thus prevent the forest advancing. This results in an open forest landscape, which is important for nature conservation and attractive for tourists. Despite their useful- ness, there are fewer and fewer wooded pastures today. The pastures are gradually becoming overgrown in many places because they have been abandoned and the cattle graze on more productive meadows. The federal government is supporting the improvement and maintenance of wooded pastures by imple- menting its forest policy (the programme “Forest Biodiversity”) and its agricultural policy (landscape quality and biodiversity subsidies).
Table 4.7.2
Area and forest distribution of the wooded pastures in the Jura and in the whole of Switzerland. Source: FOEN-Erhebung 2006
Region Area of wooded
pastures in ha
Proportion of Switzerland’s forest area in %
Jura (VD, BE, NE, JU) 45,000 3.6
Rest of Switzerland, especially the Alps
42,000 3.4
Switzerland 87,000 7.0
Table 4.7.1
Development of the forest area and number of patches of forest in Switzerland. Source: NFI and Land-Use Statistics (Arealstatistik)
Change in the forest area 1993/95 to 2009/13 in %
Change in the number of patches of forest 1997–2009 in %
Trend in the develop- ment of the forest pattern: larger patches of forest, fewer edge effects
1997 2009
Jura –0.2 +0.1
Swiss Plateau –0.1 +0.3
Pre-Alps +3.6 –1.5
Alps +10.3 –5.0
Southern slopes of the Alps
+16.8 –11.9
Switzerland +5.9 –2.5
