Cushion bogs
Phyllachne colensoi in cushion bog at Arthur´s Pass (Peter Williams)
Cushion bogs primarily occur in mountainous, typically alpine, situations. Wetlands with cushion-forming angiosperms appear unique to the Southern Hemisphere and wet tropics. The water comes from heavy rain or drainage from surrounding slopes. Some of the most widespread wetland cushion plants include Centrolepis ciliata, Donatia novae-zelandiae, Gaimardia setacea, the comb sedge (Oreobolus pectinatus), and Phyllachne colensoi, and the mat-formers Coprosma perpusilla subsp. perpusilla and Pentachondra pumila.
Where do they occur?
In the North Island, sites supporting cushion bogs occur in most of the high mountains from the Coromandel southwards; along the Main Divide (e.g. Raukumara, Kaimanawa, Ruahine ,Tararua, and Rumutaka ranges), outlying ranges such as the Herangi Range and Coromandel Ranges, and Mt Ruapehu. In the South Island cushion bogs occur in the western ranges from Nelson to Fiordland, and also in some of the eastern ranges of Marlborough, Canterbury, Otago, and Southland. Cushion bogs are widespread on Stewart Island.
Notable flora and fauna
Threatened and rare plants include the nationally critical Chaerophyllum [Oreomyrrhis] colensoi var. delicatula, the nationally endangered papataniwha (Lagenifera montana) and Coprosma talbrockiei, the range-restricted Juncus scheuchzerioides, and the naturally uncommon sun orchid (Thelymitra formosa), Ranunculus simulans, Ranunculus maculatus, Carex lachenalii subsp. parkeri, Campbell Island gentian (Gentiana antarctica), Chatham Island gentian (Gentiana chathamica), Gentianella lineata, Plantago obconica and Plantago aucklandica.
No information on threatened and rare fauna is available.
Threat status
Not threatened (Holdaway et al. 2012)Threats
Plants have to be able to withstand the low-nutrient waterlogged ecosystem, usually inhospitable climate and often subalpine/montane conditions. Feral ungulates can cause considerable damage by trampling in the high mountains. There is low visitation by the public, but some trampling at the edges by trampers when cushion bogs occur nearby walking tracks.
Further reading
Dawson JW 1988. Cushion Bogs in Forest Vines to Snow Tussocks: The Story of New Zealand Plants. Victoria University Press, Wellington.
Druce AP, Williams PA, Heine JC 1987. Vegetation and flora of Tertiary calcareous rocks in the mountains of Western Nelson, New Zealand. New Zealand Journal of Botany 25: 41-78.
Johnson P, Gerbeaux P 2004. Wetland types in New Zealand. Wellington, Department of Conservation.
Mark AF 1977. Vegetation of Mount Aspiring National Park, New Zealand. Wellington, National Parks Authority.
Mark AF, Bliss LC 1970. The high-alpine vegetation of Central Otago, New Zealand. New Zealand Journal of Botany 8: 381-451.
Talbot JM, Mark AF, Wilson JB 1992. Vegetation-environment relations in snowbanks on the Rock and Pillar Range, Central Otago. New Zealand Journal of Botany 30: 271-297.
Wardle P 1979. Plants and landscape in Westland National Park. National Parks Science Series No. 3. Wellington, Department of Lands and Survey.
Williams PA 1991. Subalpine and alpine vegetation of granite ranges in Western Nelson, New Zealand. New Zealand Journal of Botany 29: 317-330.
Wilson HD 1976. Vegetation of Mount Cook National Park, New Zealand. Wellington, Lands and Survey Department.
Links
Wetlands Restoration Handbook - Wetland Types