Sunday, 6 April 2014

A report of a trip I took to Corsica in 2004

A Continent-like Geography

Corsica has a lot packed into a small area. It is 180 km long and 83 km wide. It covers an area only slightly larger than North Yorkshire, but with less than half its population. Its physical geography reads more like a continent than a small island. It has about 1000 miles of coastline and more than 100 peaks over 2000m. Unlike many islands in the Mediterranean, Corsica has rivers that flow all year round, fed by snow from the highest peaks. This makes Corsica the sparsest populated and the most mountainous island in the western Mediterranean. Habitats of interest to botanists abound. Around the coast are marshes, lagoons, cliffs, dunes, and beaches of sand and shingle. Cultivated land is typically Mediterranean, with meadows, olive groves, chestnut plantations and vineyards. While an impenetrable maquis covers uncultivated land at low elevations; at higher altitude are large forests of Oak and Pine and ascending further still, you can find a true alpine flora.

The mountains of Corsica are built predominantly of granite and rhyolite and though the island is geographically close to Italy, the mountains originate from a thirty million year old chain of mountains that stretched across northern Spain, through the Pyrenees and into the Alps.  Since then, the land mass that includes Corsica and Sardinia has moved south-eastwards and rotated anticlockwise to its present position. Though the topography is dominated by igneous and metamorphic rocks there are some sedimentary rocks, particularly along the east-coast. There are only three small outcrops of limestone rocks, but these are disproportionately important for a number of endemic plants.

More than 130 plant taxa are endemic Corsica and another 75 are only known from the Corsican-Sardinian archipelago. Amongst these are two endemic monospecific genera (Morisia monanthos and Nananthea perpusilla) and a number of other paleoendemics. Some of these endemics are widespread within the island, such as the Corsican Hellebore (Helleborus lividus subsp. corsicus) and the Corsican crocus (Crocus corsicus). Others, such as Brassica insularis and a number of Limonium and Ophrys species, are restricted to limited lengths of coastline and to outcrops of limestone, respectively.

History Has Aided the Conservation of Corsica

Corsica has frequently suffered as a pawn in the power struggles of stronger neighbors. The Pisans, then the Genoese ruled the island for a long time, but Corsica's strategic importance and its vulnerability to seaborne invasion kept the political position of the island unstable until the very end of the 18th century. Napoleon Bonaparte took control of the Island from the British in 1796 and, although he was born of a Corsican family and originally expressed ideas of Corsican nationalism, he did as much as anyone to Gallicise the island. Corsica's problems have not all been created by external powers. The code of the vendetta, which set family against family for generations, reached a peak at the turn of the 17th and 18th centuries. At this time, official records show that about 900 people were being murdered each year out of a population of about 120,000.

Fighting over the ownership of Corsica and under-investment by those rulers have encouraged emigration and has kept the population small. Between the 8th and 18th centuries raids from pirates and slavers forced people to inhabit villages away from the coast. Compounding the political difficulties the mountainous terrain makes communication and transportation difficult and restricts areas suitable for agriculture. Though potentially destructive activities such as overgrazing, charcoal production and timber extraction occur on Corsica they have been moderate, at least in comparison with other Mediterranean islands. Though these geographic and political factors have protected Corsican wildlife to some extent, they have done little to help the Corsican citizens, who have never been wealthy and often favoured their own leaders and system of justice over that of their overseas rulers.

A number of different organisations are involved in conservation on the island, but the largest is the organisation of the Parc Naturel Régional de Corse (PNRC). Founded in 1972 the PNRC covers almost a third of the island and protects an abundance of wildlife. It has a much broader mission than wildlife conservation. It also aims to protect the cultural heritage and the way of life of rural Corsica, while attempting to stimulate enterprise in the much-abandoned villages. While the PNRC oversees conservation in the mountainous centre of the island, many coastal sites are protected by the Conservatoire du Littoral. This is a national organisation dedicated to protecting coastal sites. Though there are many reserves and areas of botanical interest, two in particular deserve mention. Firstly, the Valley of the Fango River, which has been designated a biosphere reserve by UNESCO since 1977, and secondly, the neighboring reserve of Scandola, which is almost entirely inaccessible by land, but includes a large marine reserve. Together, these reserves contain some of the best preserved habitats in the Mediterranean basin. Not only are they important for their flora, but also for their populations of birds, reptiles, fish, amphibians and mammals.

Diverse Forests

Corsica has some extensive forests of native pines and oaks. Perhaps the most inspiring and emblematic are those of Corsican pine (Pinus nigra subsp. larico). These trees can grow to over 50m tall and can live for many hundreds of years. They form forests at altitudes between 900m and 1800m, which are important habitat not only for native plants, but also the endemic and elusive Corsican Nuthatch (Sitta whiteheadi). The variation in relief and rainfall around the island makes for varied forests. On the hills and mountains, in addition to Corsican Pine, are species such as Maritime Pine (Pinus pinaster); Yew (Taxus baccata); Flowering Ash (Fraxinus ornus); Holm Oak (Quercus ilex); Beech (Fagus sylvatica) and Silver Fir (Abies alba). While in wet areas there are Alders (Alnus glutinosa), Willows (Salix alba etc) and the Narrow-leaved Ash (Fraxinus angustifolia). There are also species one might not expect on a Mediterranean island for example Fragrant Alder (Alnus viridis subsp. suaveolens) is an endemic taxa of a species that is found in the mountains of central Europe, northern Asia and North America. It does not grow to much more than 3m, so cannot be called a forest tree, yet it does form dense stands in the sub-alpine zone (1600m-2100m), frequently together with the taller Mountain Ash (Sorbus aucuparia subsp. praemorsa).

Osumda regalis


Wetlands habitats do not instantly spring to mind when thinking of the environment of Mediterranean islands; yet they contribute greatly to the overall biodiversity of Corsica. These habitats include coastal lagoons, marshes, seasonal ponds, rivers, streams, alpine lakes and bogs. Along the east coast are the largest lagoons, such as the Étang de Biguglia.  A literal translation of the word "étang" is "pond", though this is no pond, being 11km long and 2.5 km wide. The Étang de Biguglia is an important reserve for all sorts of creeping, flying and swimming wildlife, but it is also home to a number of rare plant species, including Kosteletzkya pentacarpos, a beautiful member of the Malvaceae. This species is found around the Mediterranean basin, but only where suitable marshland habitat exists.

Site Naturel de la Vallée du Fango
The tides around Corsica do not amount to more than 40cm, so saltmarshes like those on oceanic coasts are not found. Nevertheless, there are a number of saline "wetland" habitats, known in French as sansouire. These are characterised by winter inundation with seawater and then drying in the summer.  A number of halophytes, particularly halophytic members of the Chenopodiaceae (Salicornia, Sarcocornia etc), populate these highly saline habitats. Also near the coast are a number of freshwater ponds, some of which dry out during the summer. Unusual plants such as Baldellia ranunculoides, Ranunculus ophioglossifolius and Pilularia minuta can be found in these uncommon habitats.

The Royal Fern (Osmunda regalis), which has declined across northern Europe, is still common along streams in Corsica as well as in inundated woodlands. It is a species of shady wet habitats on acidic soils and in much of Europe it has been lost where these habitats have been drained. Corsica's rivers, streams and torrents are also home for several endemic species including Doronicum corsicum, Hypericum corsicum and Narthecium reverchonii.
Narthecium reverchonii Celak

 One of the unique wetland habitats of Corsica are the pozzines, which are found between altitudes of 1600m and 2200m. The pozzines are bogs that are frequently traversed by serpentine streams and are pitted with circular pools. These pools give the bogs their name, as the name possine is derived from the Corsican word for pit (Pozzi). Some of the species found in these bogs are more common in Northern Europe than the Mediterranean, for example Drosera rotundifolia and Menyanthes trifoliata, while others are unique to Corsica such as Pinguicula corsica, Bellis bernardii and Juncus requienii.

It is interesting to note that although the species epithets corsicum, corsicus and corsica are used extensively for the islands endemic plants, a number of other names are frequently encountered, for example soleirolii, reverchonii, briquetii and conradii. These names commemorate the botanists Captain Joseph Francois Soleirol (1796-1863); Elisée Reverchon (1835-1914); John Briquet (1870-1931) and Marcelle Conrad (1897-1990). Notice that these botanists were working at a time when the flora of continental France was largely described. Yet whole habitats such as the pozzines were unknown to scientists until the latter half of the twentieth century.

Risks To The Flora

With large areas of forests and scrub, fires are a serious issue on Corsica. Fires are usually started for one of three reasons. They may be unintentionally started; they may be started maliciously, or they may be started intentionally to clear land. At one time the European Union grant system for breeders of nursing cows led to an increase in fires. Farmers were using fires to increase their grazing land to comply with the requirements for subsidies; fortunately, these grants have now been suspended. The EEC has actually made many positive contributions to the island's economy including significant funds for fire prevention and protection on the island. There is a small army of people involved in fire fighting and they possess an arsenal of modern equipment such as recognisance planes and water bombers. Still, on average about 8,200 hectares are burnt each year. While much of the vegetation of the Mediterranean can recover rapidly from fires, even these habitats do not respond well to frequent fires, which contribute significantly to soil erosion.

Opuntia ficus-indica
Alien plants have been introduced to Corsica since at least the Roman period and many of those species, such as the Olive, are as much part of the landscape as the native plants. Yet modern introductions, many from different continents, present a threat to native plants. About 140 species have naturalised on the island and many others are planted or are casual. Two of the most destructive are the South African succulents Carpobrotus edulis and C. acinaciformis. These species form mats over coastal rocks, eliminating all other plants. Another South African introduction, Cotula coronopifolia, poses a threat to wetlands. In places, this plant has become the dominant species, eliminating practically all other herbs. A number of other potentially damaging species have naturalised or are planted such as Prickly Pear (Opuntia ficus-indica); Bermuda buttercup (Oxalis per-caprae) and several Eucalyptus species.

Changes in farming practices have had both positive and negative impacts on native plants. Since world war two there has been continual migration out of villages and a decline in traditional farming. The cultivation of chestnuts and the maintenance of terraces have declined in the hills, whereas in the lowlands vineyards have increased as has the growing of non-traditional crops such as kiwi fruit. At one time, the annual movements of livestock, known as transhumance, were an important element of agriculture in the mountains. However, these days the ancient mountain trackways are more frequently used as hiking trails.

Improvements in the roads and increased ownership of four wheel drive vehicles have made once remote corners of the island accessible. Even high altitude has not protected the pozzines from damage and popular hiking routes to the high mountain lakes have been rerouted where damage was occurring. With jeeps and motorbikes, tourists can visit once deserted beaches that are only accessible by rough tracks and these days damage to dune systems by motor-sports is common. Other risks include the collection of wild plants for gardens or for their medicinal properties. Wetlands are particularly vulnerable as they can easily be drained or overgrazed.

One should not overplay the risks though. Corsicans, in general, are proud of their environmental heritage and one can hardly deny the Corsicans the improvements in lifestyle that decent roads and an adequate infrastructure bring. Here, I can only give a flavour of the flora of Corsica and hint at the conservation challenges. I encourage you to learn more about Corsica, even though you may need to learn some French to do so. Corsica's history has protected its wildlife to some extent, but in the future, it will be a challenge to balance the aspirations of the people with environmental protection. Still, in this respect, Corsica is not unique and it is fortunate to have a population and institutions friendly towards environmental protection.

This work by Quentin Groom is licensed under a Creative Commons Attribution 3.0 Unported License.

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