Active sand dunes
Active sand dune dominated by golden sand sedge/pingao, Ficinia spiralis, Big Bay, Western Fiordland (Susan Wiser)
Active sand dunes are those dune lands whose physical landscape and ecological character results from continuously moving wind–blown sand. They are predominantly coastal, geomorphically unstable, mobile (Johnson & Rogers 2003) and bare to sparsely vegetated (Hilton et al. 2000). Dunes are regarded as active or mobile if there is any possibility that exposed, dry (usually unvegetated) sand will be susceptible to further wind action (Hesp 2000).
Where do they occur?
Active sand dunes occur in many coastal areas of the North, South and Stewart islands, and on some offshore islands as well.
Notable flora and fauna
Threatened plants include nationally critical Holloway's crystalwort (Atriplex hollowayi ), nationally endangered crystalwort (Atriplex billardierei ), mingimingi (Muehlenbeckia astonii ), Pimelea aff. villosa (subsp. arenaria) AK 216133, nationally vulnerable New Zealand iris (Libertia peregrinans ), the declining shore spurge (Euphorbia glauca ), sand tussock (Poa billardierei), sand daphne (Pimelea villosa subsp. arenaria), Southern sand daphne (Pimelea lyallii ), pingao (Ficinia spiralis), naturally uncommon Buchanan’s orache (Atriplex buchananii ), kokihi (Tetragonia tetragonioides ) and sand wind grass (Lachnagrostis ammobia).
Threatened fauna include the range restricted snail Therasia sp. ´chathamensis´, the nationally endangered endemic dune snail (Succinea archeyi), the Lepidoptera naturally uncommon Kiwaia jeanae, nationally vulnerable Kupea electilis, naturally uncommon Scythris niphozela, declining Ericodesma aerodana, relict Samana acutata, and Orocrambus callirrhous, and the Chatham Islands chestnut weevil (Thotmus halli) (possibly extinct).
Threat status
Endangered (Holdaway et al. 2012)
Threats
Exotic plants are a major threat, especially marram grass (Ammophila arenaria), South African ice plant (Carpobrotus edulis), tree lupin (Lupinus arboreus) [all three were originally planted for dune stabilisation] and gorse (Ulex europaeus). Coastal development is also a major threat; many beaches have housing on dunes and demand for coastal properties is high. Irresponsible use of ATVs and 4WD vehicles is a problem in some areas. Rabbits threaten many rare sand dune species (Norbury 1996).
Further reading
Courtney S 1984. Our disappearing natural dunelands. Forest and Bird 15(3): 2–15.
Dawson JW 1988. Sand dunes in Forest vines to snow tussocks: the story of New Zealand plants. Victoria University Press, Wellington. Pp. 157-158.
Dugdale JS 2001. Cloudy Bay coastal habitats: entomological values of the foreshore and associated inland habitats. Department of Conservation Occasional Publication 49. Wellington, Department of Conservation. 28 p.
Hesp PA 2000. Coastal sand dunes: form and function. Coastal Dune Vegetation Network Bulletin 4. Rotorua, Forest Research. 28 p.
Hilton MJ, 2006. The loss of New Zealand's active dunes and the spread of marram grass (Ammophila arenaria). New Zealand Geographer 62: 105–120.
Hilton M, Macauley U, Henderson R 2000. Inventory of New Zealand´s active dunelands. Science for Conservation 157. Department of Conservation, Wellington. 35 p.
Johnson PN 1992. The sand dune and beach vegetation inventory of New Zealand. II. South Island and Stewart Island. DSIR Land Resources Scientific Report Number 16, DSIR Land Resources, Christchurch. 278 p.
Johnson PN, Rogers G 2003. Ephemeral wetlands and their turfs in New Zealand. Science for Conservation 230. Department of Conservation, Wellington. 109 p.
Lim DD 2012. Marram grass seed ecology: the nature of the seed bank and secondary dispersal (Thesis, Master of Science). University of Otago. 191 p.
Norbury D 1996. The effect of rabbits on conservation values. Science for Conservation 34. Wellington, Department of Conservation. 32 p.
Partridge TR 1992. The sand dune and beach vegetation inventory of New Zealand. I. North Island. DSIR Land Resources Scientific Report Number 15. Christchurch, DSIR Land Resources. 253 p.
Patrick B. 1994. Lepidoptera of Kaitorete Spit, Canterbury . New Zealand Entomologist 17: 52–63.
Links
Active sand dune extent (Stats NZ)
Caring for Northland's dunes (Northland Regional Council)
Coastal Dunes: Geomorphology (Nature Education Knowledge)
Coastal Sand Dunes Form and Function (Department of Conservation)
Dune (Wikipedia)
Dune lands (Te Ara - Encyclopedia of New Zealand)
Dune planting guide (Auckland Council)
Dune restoration (Department of Conservation)
Dune Restoration Trust of New Zealand
Farmer destroys threatened native shrub (Radio New Zealand)
Weed control options for coastal sand dunes - a review (Scion)