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Quality of Valuable Habitats (Z11)
 
Designed to cover changes in the quality of valuable habitats, the Z11 indicator now presents initial results regarding mires. While mires do not qualify as biodiversity hotspots—indeed, they harbor a relatively small number of animal and plants species—, mire-dwelling organisms typically rely on this type of habitat, i.e. they do not occur elsewhere. In addition to being rare to begin with, many mire-dwellers are already redlisted. Mires themselves are fairly rare elements of the landscape and, as such, in need of protection.
 
Between 1997 and 2006, mires in Switzerland went through a substantial decrease in quality. Roughly one quarter turned into considerably drier, more nutrient-rich ecosystems during this period. Moreover, approximately one fifth incurred a significant loss in peat content. In almost one third of all Swiss mires, the share of woody plants increased greatly. Due to these developments, mires gradually lose their characteristic features. Roughly 15% of all mires sustained a noticeable loss in mire nature.

The overall surface area of raised bogs and fens was minimally reduced by roughly 1%. However, surface shares among mire types have shifted: raised bogs shrank by 10%, peat-forming fens decreased by 6%, and non-peat-forming fens increased by 9%.

Despite their success, regenerative measures are few and far between and therefore unable to offset losses in quality.
 
 
Development in Switzerland
 

Mire nature

moor

Comments
• Changes of mire nature are measured by the so-called mire index. It reflects the share of typical mire species in the vegetation as well as their degrees of species cover. An increasing mire index equals an increase in mire nature.
• Even though the sites concerned continue to be considered mires, these changes are alarming, since more mires are losing in mire nature than gaining it.

 

Moisture content

feuchte

Comments
• Constant moisture due to a surplus of water is a central feature of mires. When they start to dry up, their mineralization rate rises and, as a result, so does their nutrient content. In addition, the probability of scrub encroachment increases.
• Roughly one third of Switzerland’s mires registered a significant change in their water balance. In general, they have become drier.

 

Nutrient supply

naehrstoffe

Comments
• Mire nutrients are derived from various sources. While direct nutrient influx from the air cannot be prevented, nutrients also enter mires by way of—usually illegal—fertilization. In addition, nutrients are absorbed from neighboring agricultural land or inflowing water. Mires also increase their nutrient supply as a result of organic materials releasing nutrients due to desiccation and mineralization.
• As a rule, mires are not wanted to increase their nutrient supply.
• The nutrient supply has increased in all three mire types. This is an alarming development!

 

Humus content

humus

Comments
• A mire’s humus value indicates the amount of organic substances found in its soil.
• The humus value has dropped significantly in roughly one quarter of Switzerland’s mires, above all affecting raised bogs—a disturbing development indeed.

 

Share of woody plants

gehoelz

Comments
• Isolated trees or shrubs, typically of stunted growth, are a normal mire component. However, a closed shrub or tree layer will displace the light-loving mire vegetation. In raised bogs, an increase of woody plants is usually caused by disturbances of the water balance. Fens undergo scrub or forest encroachment due to a combination of insufficient land use (when they are no longer mowed or grazed) and desiccation.
• All over Switzerland, the share of woody plants has significantly increased in all three mire types. From a nature conservation point of view, scrub or forest encroachment of mires is always an unwanted development, as it turns near-natural open country into forest, causing the typical mire vegetation to disappear.

Source
All information is based on the results of the Swiss Mire Monitoring Program by the Swiss Federal Institute for Forest, Snow and Landscape Research WSL as commissioned by the FOEN. For more information, please see Klaus, G., (ed.): Zustand und Entwicklung der Moore in der Schweiz. Ergebnisse der Erfolgskontrolle Moorschutz. Status: June 2007. Federal Office for the Environment, 97 p. (not available in English). For BDM purposes, data applying to Switzerland’s six biogeographical regions were recalculated by Meinrad Küchler of the WSL.
 
 
Development in the Regions
 
Data not available
 
 
Significance for biodiversity
 
Mires are isolated patch habitats, but they are not biodiversity hotspots, i.e. sites featuring a particularly high number of species. As a matter of fact, mires—above all raised bogs—are rather poor in species, even though they are composed of markedly differing types of vegetation. With their water level permanently high, mires are wet and, apart from calcareous small sedge fens, very acid and nutrient-deficient. Furthermore, despite their increased occurrence in certain regions, mires are rare. Nowadays, mires amount to a mere 0.54% of Switzerland’s overall expanse.

Raised bogs and fens of national importance harbor roughly one fourth of all vascular endangered plant species in Switzerland. Each of the wide range of vegetation types contained within mires offers a habitat for specific species, which makes mires irreplaceable. Particularly high numbers of endangered plant species grow in so-called hollows, shallow basins typical of intact raised bogs. Almost 10% of plant species to be found in hollows are on Switzerland’s Red List of endangered ferns and flowering plants.

Aside from specialized plants, especially various peat mosses and lichens occurring only in these habitats, mires are also home to fungi and very specialized animals. A wide range of dragonfly species, for example, cannot exist without hollows, rills (drainage channels) and bog ponds. If these structures were to disappear, so would such specialized species, as they have no alternative habitat to escape to. The same goes for butterfly species whose caterpillars feed exclusively on mire plants.

Moreover, mires—particularly peat bogs—are biodiversity archives. Not only pollen, but also large remains of plants and animals will be conserved by this acid and water-saturated environment for ten thousands of years. Whenever peat bogs dry up, the peat is mineralized, irreversibly destroying the archives it contains.

Last but not least, mires are important elements of the landscape and as such of biodiversity, albeit on an ecosystem level.
 
 
Further Information
 

Responsible for Z11
Meinrad Küttel, meinrad.kuettel@bafu.admin.ch, +41 (0)31 322 93 24

WSL expert contact
Meinrad Küchler, meinrad.kuechler@wsl.ch, +41 (0)44 739 24 67

Additional sources of information
> Federal Office for the Environment FOEN
> Swiss Federal Institute for Forest, Snow and Landscape Research WSL
 
 
Data sheets
 
> Complete Z11 datasheet (1.8 MB)
 
 
Status
 
This information is based on document 737 316.10 Produkt Z11 V1_en.doc dated August 25, 2008.

The Z11 indicator will be updated once additional Federal Habitat Inventories have produced monitoring results.
 
 
 
     
       
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