Biodiversity Hotspot Alps
The Alps are the most intensely used mountain region of the world. Nevertheless, they are the most important source and refuge of the European biodiversity. Many plant and animal species live only there. Species that are endangered or have disappeared elsewhere still find an intact living space in the mountain range.
by Yann Kohler, University of Grenoble - Institute of Alpine Geography and ALPARC - Alpine Network of Protected Areas
Of all people in the world, 12% live in mountains and 50% depend on goods and services from mountain regions, such as water (KÖRNER & SPEHN 2002). While mountains cover one fifth of the terrestrial land area outside the polar regions, the Alpine life zone (above the treeline) makes up only 3% of the earth surface, but harbours at least 10,000 or 4% of all vascular plant species. This disproportionate richness in species is important for slope stability, one of the key ecosystem services in mountains (KÖRNER & SPEHN 2002). Mountain biodiversity is of prime conservation value, as mountains host half of all 34 global diversity hotspots (CONSERVATION INTERNATIONAL 2007).
Biodiversity – the Diversity of Species?
According to GASTON & SPICER (2004), biodiversity can be defined as a "variation of life at all levels of biological organization". Three levels of biodiversity can be identified:
- Genetic diversity:
Describes the diversity of genes within a species. There is a genetic variability among the populations and the individuals of the same species. This diversity represents the capacity of each species to adapt to particular living conditions of different environments. The higher the genetic diversity between individuals of a given species, the better they will be able to adapt themselves to environmental changes. Although Alpine species are often long-lived and geographically isolated, their genetic diversity within populations is surprisingly high due to effective breeding systems.
- Species diversity:
Describes the diversity among species in a region. The more species are present in a region, the higher its biodiversity. Near the Lautaret pass, in the Ecrins Massif in the French Alps for example, no less than 1,500 plant species can be found in a 20 km˛ area, which represents no less than one third of the entire French flora.
- Ecosystem diversity:
The third level appears at a higher level of organization. It describes the diversity of species associations or of ecosystems in a given region. Screes, Alpine meadows, larch forests, peat-bogs, etc. are only a small fraction of the different ecosystems existing in the Alps. In the hedge-row landscapes of the Hohe Tauern national park in Austria, a large diversity of different small habitats are assembled like a mosaic in a well interconnected ecosystem.
Hedge-row landscape in the French Alps (Source: KOHLER & STOECKL).
Habitats, species, genes: the biodiversity in mountain regions is very rich at all levels. The Alps are no exception to this rule. The particularly high diversity of mountain regions can be explained by four main factors:
- The altitudinal belts. From the valley bottoms up to the high mountain peaks, from the hill level to the Alpine or even snow level, the Alps offer very different living conditions at different altitudes.
- The topography. Different slope expositions (north - south) and micro relief structures can lead to completely different living conditions within a few meters.
- The great geologic variety. The different rock types (limestone, gneiss, gypsum …) entail the constitution of different soil types that are the basis for particular vegetal formations.
This great variety of different living conditions and the small-scale habitat diversity results in a large number of different habitat types: from habitats of central Europe up to habitats of the high Nordic regions, a multitude of European habitat types are represented. In general, it can be assessed that mountain regions are more diverse than lowlands. They support about one quarter of the terrestrial biological diversity, with nearly half of the world’s biodiversity hotspots concentrated in mountains.
- The last parameter are climatic influences. The Alps are facing particular climatic influences that are often mixed with each other. The Mercantour massif in the French Maritime Alps for example is subject to mediterranean, continental and Alpine influences. With increasing altitude, the temperature drops half a degree Celsius every hundred meters and at the same time, precipitation can increase considerably.