Hill & Preston (1998) carried out an analysis of the bryophytes of the British Isles in terms of world distribution, habitat and distribution in the British Isles. They established a system of elements based on distribution in northern and western Eurasia, dividing the flora up first into latitudinal categories and secondly into longitudinal ones. They recognised four major biomes (large, naturally occurring zones of dominant vegetation adapted to the particular conditions in which they occur) and these are listed below. Many species occur in more than one major biome and five composite categories, also listed below, were recognised. The floristic element/eastern limit category or biome to which each species belongs is given in italics in the distribution data of that species.

Major biomes

1. Arctic-montane. Species with their main distribution either to the north of or (on mountains) above the tree line, or both.

2. Boreal-montane. Species with their main distribution in the coniferous forest zone. They may occur in the Boreal zone and/or in the coniferous forest zone of mountains to the south.

3. Temperate. Species with their main distribution in the cool temperate, broad-leaved deciduous forest zone. May occur on mountains to the south or in cool steppes in continental interiors.

4. Southern. Species with their main distribution in the warm temperate zone south of the broad-leaved deciduous forest zone.

Composite categories

1. Boreo-arctic Montane. Species occurring in both Arctic-montane and Boreal-montane zones.

2. Boreo-temperate. Occurring more or less equally in the Boreal and Temperate zones or, if absent from the Boreal Zonobiome, ascending to the subalpine zone on mountains.

3. Southern-temperate. Species which are found more or less equally in the Temperate and Southern (Mediterranean) zones.

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