Herbfield (coastal turf) ecosystem (SA5)

Coastal saline ecosystem

About this ecosystem

Herbfield, commonly known as coastal turf, occurs where strong, salt-laden winds are present. It grows on hard rock and occasionally sand and gravel. Due to the harsh conditions, only short stature vegetation (usually less than 50mm high) can establish. 

In Auckland, small patches of this ecosystem can be found:

  • along the south Muriwai to the Waitākere coastline
  • along the north-eastern coast of Great Barrier Island
  • on the Hauraki Gulf islands.
Rough rocky beach surrounded by grassy cliffs.
Coastal turf on the south Muriwai coastline.
Photo credit: Jason Hosking

Flora and fauna in this ecosystem

Although coastal turf occupies a small area, it is highly diverse with over 130 indigenous species recorded. It is dominated by salt tolerant herbs, sedges and grasses.

This ecosystem provides roosting and nesting habitats for:

  • shags
  • terns
  • gulls
  • gannets.
Turf bordering on sandy dunes with tall grass in the background.
Coastal turf south of Piha.
Photo credit: Jay Farnworth

Threats to this ecosystem

This ecosystem is critically endangered. 

In pre-human times, it was used by many herbivorous birds as well as resting and haul out sites for seals and seabirds. These birds and mammals may have contributed to the development and enhancement of sites through disturbance, grazing and increased nutrients.

With the loss of fauna from these sites after human settlement, many areas of coastal turf have been replaced with larger stature vegetation. Remaining areas now occur in the most windy and exposed locations.

Pest plants are a threat. In particular, salt-tolerant herbaceous species such as plantain, salt water paspalum and lotus.