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Biodiversity - What biodiversity in France?

Ecosystems in metropolitan France

The territory of metropolitan France, with its large area (550,000 km²), its significant variations in latitude, altitude, distance to the sea (diversification factors of climates), its varied geology (diversification factors of grounds), not to mention human influences, hosts varied ecosystems. To which should be added overseas communities, located in tropical, sub-tropical and sub-Antarctic areas.

Are distinguished on the territory of the European Union 6 major biogeographical zones: Atlantic, Continental, Mediterranean, Alpine, Boreal and Macaronesian. France is involved in four of these areas (the first four listed), making it the most diverse country of the Union, ahead of Spain and Italy (only 3 zones each).

The Atlantic zone concerns the 8 French regions having a coastal front over the Channel or the Atlantic Ocean, as well as Ile-de-France, the Centre and most of Midi-Pyrenees. This is the area of the plains and low hills, where we find forests like oak-hornbeam, on rich soils, with wild hyacinth (Hyacinthoides non-scripta), heathland more or less humid on poor soils, with heather (Erica cinerea, E. tetralix, E. ciliaris), where flora is unfortunately poorer.

The continental zone concerns the 4 border regions of Belgium, Germany and Switzerland as well as Burgundy, Limousin, Auvergne and a part of Rhone-Alpes. This is the area of hills and highlands, where there are beech woods and beech-oak woods, with sub-montane species, wet valleys with high Carex (Carex pendula), alluvial forests with elms (Ulmus laevis), "savarts" on calcareous soils, grazed meadows and vast artificial lakes or ponds.

The Mediterranean zone concerns the 3 regions bordered by the Mediterranean Sea (Languedoc - Roussillon, Provence“ Alpes - Cote d'Azur, Corsica). This is the area of the Olive Tree (Olea europea), green oaks and cork oaks (Quercus ilex, Q. suber), of heaths on acid soils, with lavender and Cistus, of scrublands, on neutral or alkaline soils, with Rosemary (Rosmarinus officinalis). Many ornamental plants from the regions of the world having a Mediterranean climate or similar, have been introduced there.

The montane zone concerns the massifs of the Alps and Pyrenees (essentially Rhône Alpes, Provence Alpes - Côte d'Azur and Midi Pyrénées). This is the area of Beech Forests (Fagus sylvatica) or coniferous forests (Picea abies, Abies alba, Larix decidua), of acidophilous lawns of bent Carex (Carex curvula) and Fescues (Festuca varia, F. eskia, F. supina), of Rhododendron bushes (Rhododendron ferrugineum) or green alder (Alnus viridis), of snow beds and boulders in cress (Arabis alpina, A. caerulea) and Thlaspi (Thlaspi rotundifolium).

The French metropolitan flora

France hosts approximately 4,900 species of native higher plants (called Tracheophytes consisting of Pteridophytes, Gymnosperms, Angiosperms and Chlamydosperms), which puts it just behind three Mediterranean countries: Spain (7,500 species), Italy (5,600 species) and Greece (5,000 species). However, it is ahead of the northern countries such as Germany (3,000 species) and the UK (1,400 species). 40% of the European species exist in France.

Added these native species, the naturalized species (from another country, and introduced intentionally or not behaving as a native species), the subspontaneous species (escaped from culture, but not propagating) and accidental species (occurring spontaneously but sporadically), it is well over 6,000 species that can be found in our country.

Apart from the small and very urbanized Ile-de-France departments, each French department hosts at least 1,200 native or naturalized species. The maximum being reached in the Alpes-maritimes, with 2,700 species.

Fauna of Metropolitan France

In the West Palaearctic context, the fauna in metropolitan France is rich and diversified, halfway between the northern countries, relatively poor in biodiversity, as they were covered in ice some 10,000 years ago, and the Mediterranean countries with high biodiversity .

It is difficult to say how many animal species exist in France since there are still whole groups of invertebrates for which knowledge is fragmentary. The number of invertebrate species is in the tens of thousands; just for insects, it is about 35,200. Vertebrates, accidental species excluded, are represented by a thousand species of which about 400 live in the marine environment.

France offers a major part of European biodiversity. It also hosts large populations of certain species, thus having a great responsibility towards the European natural heritage. For example, France is the second European country in number of species of amphibians (55% of European species). 58% of bird species nesting in Europe breed in France.

The number of introduced species is difficult to assess for invertebrates. Regarding vertebrates, about 5% of species are introduced. In some groups, this rate is very important and masks the actual specific biodiversity. Thus, regarding the fish in fresh or brackish water, only 60% of the species currently present in our area are aboriginal.

In vertebrates, only 8 species (less than 1%) are found only in France. In invertebrates, this rate is also low. Some groups are still exceptions. In Corsica are found the most endemic species, just before Pyrenees and the Alps

The degree of threat to most species of invertebrates is unknown. However, their living environments is known to endure serious harm. Regarding vertebrates, the situation is a highly contrasted from one group to the other. It is estimated that 15% of native vertebrates, including marine species, are threatened (endangered or vulnerable), the rate varying from 8% for fish to 31% for amphibians. However, the status of marine fish is poorly known. Considering only fish from brackish or freshwater, the rate is 51%.

Biodiversity in overseas communities

France occupies a unique place through the variety of its overseas territories and therefore its natural environment: from subarctic (Saint-Pierre and Miquelon) to Antarctica (Adelie Land), through tropical zones of three great oceans. Despite limited and often insular land surfaces, the biodiversity in these areas is often remarkable and gives France a great responsibility internationally in the field of conservation.

Terrestrial and marine biomes from overseas communities, mostly located in the tropical zone, are part of disparate biogeographical regions: these factors are the source of their great biological diversity, both at the international level and in relation to metropolitan France. Thus, over 98% of vertebrate fauna and 96% of vascular plants specific to France is focused on 22% of its territory that represent overseas communities (excluding Adelie Land).

Biodiversity levels in the overseas territories are exceptional both for their richness and their uniqueness. Generally, and all groups merged, overseas communities host more species than metropolitan France. Considering only endemic species, for which it is possible to calculate the total diversity, there is generally 26 times more plants, 3.5 times more molluscs, more than 100 times more freshwater fish and 60 times more endemic birds in the overseas territories than in metropolitan France; whereas no reptile or terrestrial mammal is endemic to metropolitan France, overseas communities host respectively 82 and 9-11 of these species. Thus, over 98% of vertebrate fauna and 96% of vascular plants specific to France (whose continued populations is under French responsibility) is focused on 22% of its territory that represent overseas communities.

This biodiversity reaches highlights: the originality of the flora and fauna of New Caledonia, no larger than Picardie (three departments), is beyond measure (with 2,423 plants, 21 freshwater fish, 61 reptiles, 23 birds and six mammals all endemic, the originality of these flora and fauna is of the same order as those of Europe), while the island of Rapa in French Polynesia hosts on an area equivalent to several districts of Paris (40 km²) at least 300 endemic species!