Sphagnum peatlands are threatened by overharvesting, conversion to agricultural land, hydrological changes from aquifers altered by irrigation or overuse, and damage from forest harvesting and air pollution.
Sphagnum is often considered a renewable resource that can be “harvested,” because raking after partial harvest can encourage regeneration. However, much peat harvesting, especially that for peat used as fuel, is actually mining—characterized by a complete removal of all peat layers, so that the Sphagnum cannot regenerate. Even if some Sphagnum is left during harvest, and hydrological conditions are not irrevocably altered, the moss regenerates slowly, with its peat accumulating at 10 to 40 cm (4 to 13 in) per thousand years, so it cannot be harvested again in a lifetime.
In some countries, overharvesting threatens Sphagnum peatlands—Finland, for example, is estimated to have lost 60% of its Sphagnum peatlands.
Overharvesting may pose the largest threat, but destruction of aquifers that feed peatland can pose a particularly dramatic one. When hydrological alterations or extreme drought dry out a peatland, the decomposing peat can generate methane and other flammable gases that collect in underground pockets. When ignited by lightening strikes, or auto-ignited through the combination of combustible gases, this can lead to subterranean fires that can extend to large areas of peatland, and may burn for weeks to months or years, resulting in massive releases of the CO2 that is stored in these deposits. Such fires have affected large peatlands in Indonesia, as well as a peatland in Spain that is part of a nature reserve listed on the Ramsar convention. Although it is not clear that these peatlands were Sphagnum dominated, these cases suggest the potential threats to any peatland from widespread hydrological changes.
Some studies suggest that Sphagnum is particularly sensitive to damage from air pollution, and may decline with acid rain or increased ozone.
(Anderson et al. 2009, Crandall-Stotler and Bartholomew-Began 2007, Crum 1988, Crum and Anderson 1981, Glime 2007, Lopez-Gunn et al. 2011, McQueen and Andrus 2007, Wikipedia 2012.)
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