The Flow Country is widely considered to be the largest area of blanket bog in the world. Together with associated areas of heath and open water it is of international importance as a habitat and for the diverse range of rare and unusual breeding birds it supports.
Covering about 4,000 km2 (1500 miles2), the Flow Country is a large, rolling expanse of blanket bog found in Caithness and Sutherland in Scotland. The property encompasses an exceptionally wide range of vegetation and surface pattern types, including numerous pool systems. These features are usually rare and localised but here they are widespread and a high proportion of the ground remains undisturbed. The range of mire types varies from those of the lowland Caithness plain in the east, with their continental affinities, through to those of the mountainous oceanic west. Extensive areas of active blanket bog, where bog moss Sphagnum and other bog species ensure continuing peat accumulation, occur in intimate association with a range of open water, wet heath, grassland and fen communities. This provides the diversity of habitats necessary to support a wide range of wetland and moorland species. Of particular importance are the birds, many of which are typically northern species found here towards the southern limit of their range. These include red-throated diver, black-throated diver, golden plover, greenshank, golden eagle, merlin and short-eared owl.
The Flow Country is also unusual in that it provides an extensive area of wild land and solitude on an otherwise highly developed and densely populated island. As wild areas such as these are typically mountainous, the associated blanket bog tends to be relatively fragmented and confined to the gentler slopes. As such, large, continuous areas such as the Flow Country are exceptional.
Blanket bog is a globally rare habitat, perhaps extending to some 10m ha. It is confined to the most oceanic areas of mid-high latitudes (45 - 60 degrees). This site represents around 1.5% of the global blanket bog resource.
Although no site could represent the full range of species and forms occurring throughout the global range, this site does demonstrate some remarkable diversity in response to altitude and longitude over relatively small distances. The whole area experiences an extremely oceanic climate, but within this there is a strong east-west gradient reflected in the floristic composition. Overlain on this gradient is geological and topographical variation resulting in additional species and structural diversity. This is particularly well expressed in the range of patterns of pool systems. Although analogous patterns appear on peatlands elsewhere in the world, nowhere else does such variety occur on blanket bog or over such short distances.
Thus, although distinguished from other examples, this site captures the essence of the habitat in a way which few, if any, other sites could.
In addition to the extent, continuity and diversity of peatland habitats, the size and composition of the bird population contributes to the outstanding international importance of this site. Raptors, waterfowl and waders are particularly abundant and diverse for this habitat and for many of these this is a stronghold set against declines elsewhere and predicted restrictions on range in response to climate change.
Another important aspect of the Flow Country is the history and continuity of scientific research into the habitat, its species and its supporting processes. Not only did its study contribute to some early ideas on the development, form and function of blanket bog, it is now a key site in developing our understanding of a wide range of peatland issues, from the ecology of individual species and changes in their population over time, to greenhouse gas fluxes and the role of such habitats in climate change mitigation.
(ix) The outstanding importance of the Flow Country lies in its extent and continuity, the diversity of mire and vegetation types, and the on-going processes of bog formation which it exhibits.
(x)The size and range of the bird populations that it supports, as well as concentations of other rare species.
Integrity: The blanket bogs of the Flow Country have developed in the presence of human activity more or less since the end of the last glaciation. However it is probably only in the last 200 years that there have been any significant impacts. In chronological order these have arisen through sheep farming, sporting management for red deer and, to a lesser extent, red grouse, forestry and wind farms. All of these activities have had some impact on the peatlands, but there has been no loss of species or structural diversity.
Grazing impacts generally avoid the wettest, most sensitive ground. Improvement of pasture adjacent to the peatlands has provided rich feeding ground for migratory species such as dunlin and golden plover which breed on the bogs. Drainage, to improve the grazing in some areas has had only limited success and programmes of drain-blocking have targetted key areas. Commercial forestry expansion in the 1970s and ‘80s has contributed to the loss of some of the original peatland area. This is restricted to a number of discrete areas extending to around 60,000 ha of the 400,000ha of blanket bog in the north of Scotland. Although the effect on the habitat and associated species has clearly been damaging, most of the peatlands are sufficiently distant from it for their overall integrity to be largely unaffected. Large areas are now being restored back to blanket bog, with trees having been removed from 2,200 ha in some of the most sensitive areas, and more such restoration planned. Wind farms have been largely confined to the edges of the peatlands and have been designed to avoid significant adverse impacts on the designated peatlands habitats and species.
Although several existing World Heritage Sites contain peatland, none are listed primarily for their peatland habitat and/or the species it supports. Some peatlands are, however, the primary interest on national Tentative Lists. The Great Vasyugan Mire is on the Russian Federation's Tentative List as a swamp massif that includes peat deposits of different types. Likewise, the Okefenokee National Wildlife Refuge is an extensive wetland on the USA's Tentative List. Indeed the description of the site makes reference to the Flow Country and the different nature of its peatland. Additionally, the Tentative List for Ireland includes The Céide Fields and North West Mayo Boglands which is an area of blanket bog, however it is proposed as a cultural site for its Neolithic landscape rather than its peatland interest.
The Flow Country site is widely considered to be the best, and certainly the best known, site in the world for the globally rare peatland formation known as blanket bog.
Within the UK, most of the blanket bog is in Scotland with important sites on Lewis and at Rannoch Moor. These lack the extent and diversity of form found in the Flow Country and although they share several of the key bird species, they have neither the range nor population sizes found at this site. Elsewhere in the UK, for example the Peninnes, Wales and Dartmoor, the habitat is either significantly degraded, fragmented or both.
Elsewhere in Europe the largest area of blanket bog is in Ireland. The total extent of relatively intact bog across the whole country is similar to that of the Flow Country, much reduced from its original extent due to peat extraction, forestry and agricultural expansion. The plant and bird species complements are similar although the latter lacks several of the key raptor and waterfowl species found in the Flow Country.
The other main areas of blanket bog around the world are in eastern Canada, the North American Pacific Coast, the Magellanic Tundra Complex of Patagonia, Tierra del Fuego and the Falkland Islands, New Zealand the islands of the Southern Ocean and North-east Asia. These widely scattered regions support a very diverse range of species and peat-forming processes. There is, however, some doubt as to whether at least some of them are truly blanket bog. While they occur in areas with comparable climates, are at least superficially similar in terms of overall appearance and, despite their geography often share some plant species, closer, albeit limited, investigations have cast some doubt on their classification beyond being peat-forming habitats. None of these areas has sites which are either designated World Heritage Sites, or on national Tentative Lists for supporting blanket bog, or habitats with similar characteristics, as the principal feature of interest.