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Length of linear landscape
features (E4)
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The E4 indicator «Length of Linear Landscape Features» registers changes in length affecting landscape features such as hedges, forest edges, and open watercourses.
Representing transition zones between different habitats, linear landscape features are often particularly rich in species. As they interconnect various natural landscape units, many animal species use them for migration corridors. Declining numbers of such features result in a loss of habitat, preventing numerous animal species from moving freely about the landscape. Newly created hedges or forest edges and renatured watercourses may reconnect previously isolated habitats and increase a landscape’s ecological quality.
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| Development in Switzerland |
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The table below lists changes registered in the length of linear landscape features nationwide (ARE/FOEN, 2007)[1]. Using consecutive editions of Switzerland’s National Map, signatures of individual landscape features were compared to take stock of both new and lost sections. In doing so, the indicator reveals whether linear landscape features on the whole become lengthened or shortened. Monitoring periods correspond to updating intervals of the National Map.
In order to put changes in length into perspective, it helps to view the bigger picture, comparing changes with the overall length of monitored landscape features: In 2009, Switzerland’s National Map featured 10,334 kilometers of hedges, 115,440 kilometers of forest edges, and 61,542 kilometers of watercourses. This information is based on the VECTOR25 digital dataset by swisstopo.
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| Linear landscape features |
Annual changes in length expressed in kilometers |
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1972 - 1983 |
1978 - 1989 |
1984 - 1985 |
1989 - 2003 |
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| Hedges |
33 |
55 |
156 |
62 |
| Forest edges |
no data |
no data |
no data |
703 |
| Open watercourses |
-77 |
-72 |
0 |
33 |
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Interpretation example
As indicated by National Map signatures, hedges increased by a net 62 kilometers per year between 1989 and 2003.
Comments
When National Maps used to be established manually, hedge symbols were sometimes covered to make room for inscriptions. As a result, a new hedge shown in a later edition was not necessarily newly planted, but might simply have reappeared from under the inscription. While introducing the VECTOR25 digital landscape model eliminated this particular problem, data collection continues to leave considerable leeway for interpretation. However, despite these limitations, data clearly indicates hedges to increase in length.
Forming a transition zone between forests and the open landscape, forest edges are features of great ecological importance with high species richness. The shape and surface area of forests can be changed by natural or human-made causes such as avalanches or straightening, which impacts the length of forest edges. Forest edges may also be created within a forest, for example if a storm blows down a clearing or if a road is built (SIGMAPLAN, 2007)[1].
As opposed to the 1970s and 1980s, brooks returning to the surface considerably outnumber those banished underground, owing to infiltration swales, renaturation and natural flood dynamics (ARE/FOEN, 2007)[1].
Data was derived from the third update of the Landschaft unter Druck («landscape under pressure») project of the Federal Office for Spatial Development ARE and the Federal Office for the Environment FOEN. Information is based on changes registered in the swisstopo dataset used to establish Switzerland’s National Map.
[1] Federal Office for Spatial Development ARE / Federal Office for the Environment FOEN (eds., 2007): Landschaft unter Druck. 3rd update1989–2003. Bern. (not available in English). |
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| Development in the Regions |
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| For detailed information on the development in different spatial landscape units please consult the complete E4 datasheet. |
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| Significance for biodiversity |
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A decline of linear landscape features results not only in a loss of habitat, but usually also prevents many animal species from covering their complete potential area of expansion. Conversely, newly created hedges or forest edges as well as renatured brooks may reconnect previously isolated habitats, enhancing the landscape’s value for plants and animals alike.
Due to the lack of suitable data, the E4 indicator cannot evaluate the quality of the landscape features it monitors, even though a habitat’s quality is crucial for its species diversity. Well-structured forest edges, for example, are of great importance both as independent habitats and as connecting features between forests and open grassland. This especially applies to the Central Plateau, where forests are divided up into countless forest islands. According to the Swiss National Forest Inventory of 2010, however, only about 40% of all forest edges on the Central Plateau and in the mountains offer high richness in species and structures.
The increase in hedges found on the Central Plateau and in conurbations has a favorable impact on species diversity, since every new hedge provides an additional structure in a landscape that has been «cleared out» by intensive farming and strong settlement pressure.
Underground piping of brooks depletes the landscape, causing its structure and species diversity to decline. However, many formerly culverted brooks are being renatured today, which has a favorable impact on biodiversity.
[2] Brändli, U.-B. (Red.) 2010: Results of the Third Swiss National Forest Inventory 2004-2006. Birmensdorf, Eidgenössische Forschungsanstalt für Wald, Schnee und Landschaft WSL. Bern, Bundesamt für Umwelt, BAFU. 312 S.
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| Further Information |
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In charge of this indicator
Barbara Schlup, schlup@hintermannweber.ch, +41 (0)31 310 13 03
Additional sources of information
> www.are.admin.ch (Federal Office for Spatial Development, information on the project «landscape under pressure» not available in English)
> www.bafu.admin.ch (Federal Office for the Environment, landscape information not available in English)
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| Data sheets |
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| > Complete E4 datasheet (975 kB) |
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| Status |
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This information is based on the document 875 319.10 E4 Produkt 2010 V1_En.doc dated June 3, 2010.
The indicator is updated every six years, based on the update of Switzerland’s National Map.
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