Raised Bogs are domed masses of peat that build up slowly, over thousands of years, in former lake basins or shallow depressions. They are nutrient-poor, ombrotrophic wetland ecosystems – i.e. they are fed by rainwater only, with no groundwater input. The best raised bog habitat is actively peat-forming, i.e. very wet, with lots of surface water and a high cover of bog mosses (i.e. different species of Sphagnum moss). This kind of habitat builds up the bog through the accumulation of bog moss layers over time. Typically, a raised bog will consist of high bog, i.e. an uncut bog dome, surrounded by cutover bog, where peat-cutting has taken place. At some sites, forestry plantations were established on the cutover bog, but at others, the plantations extended onto adjacent high bog.