Heathlands, dominated byCalluna vulgaris, are located along the western seaboard of Europe. Most undergo a cyclical succession as the heather plants pass through four definable growth-phases over a period of about 30 years. Examples of upland heathlands are drawn from the North York Moors National Park, an area of Jurassic rocks in the north of England (approximately 54°25′N, 0°55′W). Botanical diversity is low. In a survey of 10 heathlands selected to encompass the botanical variation of the heathlands of the National Park, only 40 species of higher plants and 31 species of mosses were recorded (2.2% and 4.5% of the British flora, respectively).