It was separated from the mainland some 8000 years ago by sea-level rise in the post glacial period. At the same time, Holy Island become isolated from the rest of Anglesey. The low-lying, undulating landscape of the island, with its diverse geological template, rises to its highest point of 230m at Holyhead Mountain. Geological structural trends are basically north-east to south-west and the drainage follows this pattern with rivers and streams flowing in these directions. The climate is oceanic with relatively small seasonal variations in temperature and rainfall. Annual rainfall varies between 750-1000mm and periods of snowfall and hard frosts occur only occasionally. Most (96%) of the island is devoid of tree cover and exposed to the prevailing south-westerly winds.

Anglesey has been an important historical focus of settlement in Wales. Agriculture seems to have flourished from the beginning of the 13th century when the island was known as "Môn Mam Cymru" the granary of Wales. The early medieval hamlets, with shared open-field systems, were gradually broken up and taken over by more compact farm units and a number of landed Estates. Arable farming subsequently declined and by the 17th century there was an increase in livestock rearing and dairy farming; enclosures had also taken place during this period and the island's current field system bordered by hedgerows and hedge banks began to become established. Since the construction of a road bridge across the Menai Strait in 1826 and later a rail link, fat stock production has become increasingly important with animals brought from the rearing districts of the mainland. The size of individual farms is still increasing, mainly through the amalgamation of small holdings, but many are still small compared to other parts of Britain, the majority being between 5-100 acres.

This agricultural history had important effects on the range of natural and semi-natural habitats on the island. The cover of deciduous woodland (4%) that still remains, for instance, is relatively low compared to other parts of Gwynedd. Although there is generally not the pressure from the most intensive farming technology practised in other parts of the country, there are problems associated with small farm units which struggle with limited acreage and where important sites for nature conservation are in multiple ownership. This has been especially significant for many peatland sites, (there is a nationally important series of calcareous valley mires on Anglesey) where variation in land-use and reclamation has led to fragmentation of habitat. On the other hand some the large estates have contributed positively by setting aside areas as game reserves and maintaining various habitats, especially woodland, in a semi-natural state.

The development of tourism has had significant implications for nature conservation in Anglesey. The coastal zone is the focus of activity and almost the entire coastline is declared as an Area of Outstanding Natural Beauty. The Anglesey coast has a number of important habitats sensitive to public pressure such as sand dune systems and cliffs with seabird colonies.

Although industry has been limited , several developments have significant implications for the natural environment of the island. The working of copper deposits on Parys Mountain since pre-Roman times, and its rise to the premier producer of copper ore during the 17th Century has left a scarred but strangely beautiful landscape on Mynydd Parys near Amlwch, with interesting mineral and floristic features. An Aluminium plant near Holyhead produced flourine emissions causing damage to the lichen flora over a wide area of north-west Anglesey - though emissions have been significantly reduced by improved technology in recent years. At Wylfa, on the north coast, a 600MW nuclear power station presents an ironic contrast to almost 100 wind turbines scattered across the north of the island. An oil transfer terminal built at Amlwch in the 1970s is no longer used (though the pipeline to Merseyside is now a gas storage and supply facility). The development of food processing has been a particular feature of the last 20 years, based on intensive chicken rearing (an estimated 2.5 million chickens on the island at any one time), an abattoir and cheese factory. These industries have brought their own problems, notably large quantities of waste and a concomitant eutrophication of land and water in many parts of the island.

Despite the presence of man on Anglesey over a long period, there are still many sites of importance for nature conservation. The island has one of the highest densities of SSSI in Britain. Of particular importance in a national and international context are the base-rich valley mires in eastern Anglesey, the sand dune systems at Newborough and Aberffraw, and the coastal cliff and heathland on Holy Island, as well as a number of geological sites.

Further Reading List