Endangered Species

Many countries publish lists as red data books of species that are in danger of becoming at least locally extinct. Such lists have prompted many studies into the ecology of these species in an effort to ensure their survival. In most cases the marginality of the species is due to the destruction of their habitat by human activity. In some cases the species have very narrow climatic and habitat limits which makes them highly dependent on the preservation of a restricted set of environmental conditions. In the British Isles, one such example is Primula scotica which is restricted to the north coast of Scotland and parts of the Orkney archipelago and survives mainly in maritime sedge heath that occurs just to landward of cliff edges. Not only is this species limited now to less than 30 sites, it also appears to have

Fig. 1.18 The snake's head fritillary (Fritillaria meleagris) growing in Magdalen meadow (Oxford). Probably a naturalized introduction as it is not recorded in Britain before 1732.

a narrow climatic window for reproduction, with seedling production dependent on mild winters and absence of storms at flowering time (Fig. 2.3).

Other endangered species may have a wider ecological niche but their habitats may be in areas that have been subjected to large-scale changes in land use. The disappearance of water meadows has reduced the distribution of many orchid species. The snake's head fritillary (Fritillaria meleagris), once widespread in damp meadows and pastures in southern England (Fig. 1.18), has suffered from modern techniques of pasture improvement and is restricted to areas where it is especially protected. Magdalen College Meadow (Oxford) is claimed to be the major refuge of the British population. Cleansing of beaches with removal of litter is also destroying the regeneration niche for many coastal species. Sea kale (Crambe maritima) is an endangered species found at the foot of cliffs where it

Fig. 1.19 Sea kale (Crambe maritima) growing on shingle at the base of a cliff in south Fife, Scotland. A species which reaches its northern limit of distribution in Fife and which could be expected to migrate northwards if there is sufficient climatic warming and its habitat is not excessively disturbed.

Fig. 1.19 Sea kale (Crambe maritima) growing on shingle at the base of a cliff in south Fife, Scotland. A species which reaches its northern limit of distribution in Fife and which could be expected to migrate northwards if there is sufficient climatic warming and its habitat is not excessively disturbed.

grows on sites with decaying seaweed (Fig. 1.19). Disturbance of shingle beaches, possibly aggravated by climatic warming, is causing a retreat northwards of another relatively rare shingle species, the oyster plant (Mertensia maritima).

The reclamation of hill land for improved pasture has resulted in a drastic reduction in moorland throughout the Atlantic seaboard of Europe. Particularly severe in terms of species loss has been the removal of many wetlands through drainage and peat extraction. On a European scale, sedges, rushes, irises, orchids and gladioli are all groups of species which have particularly suffered through habitat destruction.

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