In the “Pikao (or Pingao) the Golden Sand Sedge

The demise of the once common pikao can be attributed to the arrival of Europeans to New Zealand as inferred by the botanist Leonard Cockayne1 who stated that pikao had been common throughout the country. This decline has largely been a result of bad practices on coastal land (such as fire) and the desirability of coastal land for agricultural and forestry purposes2,3,4,5,6,7.

Examples of bad practices on coastal land can be traced back to 1880's in the Otago region in Murray Thomas's work "A Pakeha's Recollections"6. Here he describes how

"to relieve the monotony of waiting (for frost fish to strand on the beach) and at the same time cater for their comfort, the boys used to set fire to the native grass, and night saw patches of sandhills ablaze".

Consequently he noted that areas of dune that were now devoid of vegetation were blowing out, causing sand to drift over the productive land where people had settled with no signs of regeneration of the vegetation. Subsequently, Thomas introduced marram grass  (Ammophila arenaria) and yellow tree lupin (Lupinus arboreus) after other methods such as shrub fences failed to halt the drifting sand. The success of this revegetation then lead to the fervent sowing of marram grass and lupin around the Otago region, with the resultant dune reformation proclaimed to be a "most gratifying" outcome6.

This method of stabilisation based on recommendations made by Cockayne was then adopted by the Ministry of Lands at the turn of the century to deal with a growing problem of dune instability3,4 and sand drifts inland arising from damaged relict sand dunes7. It was acknowledged that factors such as fire and stock damage from trampling, uprooting and grazing were to blame for this degradation8 and large scale planting of marram and yellow tree lupin was initiated3,4. This prevented further sand drift and erosion of land which had begun because of increased wind exposure through dune blowouts3,6. It also permitted the reclamation of the extensive active dune systems associated with pikao for other purposes, primarily pasture and forestry3,4,6. An additional bonus in using lupin was its ability to fix nitrogen, eliminating the need and cost to fertilise marram, and permitted the planting of pasture and forestry3.

More contemporary examples of bad practice tend to related to recreational activity and include the removal of sand, vehicle damage (by dune buggies, trail bikes and 4-wheel drives), bonfires, as well as pressures from residential and industrial activity in coastal areas, weeds and pests and allowing stock onto dune lands.

The practice of planting marram and lupin to protect dunelands continued unabaited throughout the 20th century until the 1980's when lupin blight appeared, threatening the stability of marram dunelands3. This problem provided an opportunity to examine the potential for native to be used to once again to achieve stable dunes systems3.

Based on Cockayne's observations of what were the major indigenous sand binders, investigation into the use and restoration of these species has been advanced primarily by the Forest Research Institute, and has lead to the establishment of the Coastal Dune Vegetation Network (CDVN)3,4,5. Their findings have enabled the gradual adoption of coastal rehabilitation schemes around the country.

Unfortunately forestry management continues to use exotics species in the management of forestry estates9, many of which are located in coastal areas that would once have been part of natural dune systems.

References

  1. Cockayne, L. (1911). Report on the dune areas of New Zealand plants, their geology, botany, and reclaimation. Parlimentary Paper C. 13. Department of Lands, Wellington, New Zealand. 76p.
      
  2. DoC (1992). Pingao Recovery Plan. Otago Conservancy 1993-1998. Department of Conservation, Dunedin.
      
  3. Bergin, D. O. and Herbert, J. W. (1994). Resoration of native plant communities on sand dunes in New Zealand. Paper for the Forth Annual New South Wales Coastal Management Conference, 18-20 Oct, Gosford, Australia.
      
  4. Bergin, D. O., FitzSimons, P., Freeman, C., Herbert, J. W. and Kesby, N. A. (1997). Managment of Marram Grass in the Resoration of Indigenous Coastal Dune Vegetation in Australia and New Zealand. Paper accepted for The Pacific Coasts and Parks Conference, 7-11 Sept. Christchurch, New Zealand.
      
  5. Bergin, D. O. and Herbert, J. W. (1997). Revegetation of Coastal Sand Dunes in New Zealand using Indigenous Species. Combined Australian Coastal Engineering and Ports Conference, Christchurch, New Zealand.
      
  6. Thomas, M. G. (1944). A Pakeha's recollections. The reminicences of Murray Gladstone Thomas. Extracts relating to early Dunedin. Eccles, A. (ed). A. H. & A. W. Reed.
      
  7. Moore, L. B. and Adams, N. M. (1963). Plants of the New Zealand Coast. Paul's Arcade, Hamilton and Auckland.
      
  8. Cockayne, L. (1919). New Zealand plants and their story. Second edition, Governement Printer, Wellington. 269p.
      
  9. Gadgil, R. L., Sandberg, A. M. and Lowe, A. T. (1999). Two seedling rooting media and subsequent growth of a N-fixing plants in a New Zealand coastal sand-dune environment. New Zealand Journal of Forestry Science, 29(2), 195-202.

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