Manawa Karioi was once host to a range of vegetation types. Our medium term goal is to restore a range of plants appropriate for the site and then allow nature to take over – with minimal ongoing intervention.
The upper slopes and ridges will become shrublands typical of the northern Cook Strait coast. Trees and shrubs such as tauhinu, mingimingi, coastal flax and kōkōmuka tāranga will be planted as they can tolerate salty wind, drought and low soil fertility. This vegetation may be limited to a height of two to five metres, but taller vegetation may develop in time.
The lower slopes are more sheltered but usually quite dry in summer. Drier, north-facing slopes will host only some of the taller trees like rewarewa, rāta and tōtara. Kohekohe will form the main canopy on the damper, south-facing slopes.
In the gullies the bush will consist of five layers typical of forests further inland. A key difference is the presence of kohekohe, a frost-sensitive tree not usually found more than 10km inland.
The 5 Layers of the Forest
The emergent layer
- Scattered trees often over 30 metres tall that tower over the lower canopy trees
- Ancient forests often contain slower growing podocarps (cone-bearing species that evolved millions of years before flowering plants) such as rimu, tōtara, miro and mataī
- Regenerating forests often contain faster growing, flowering trees such as rewarewa
- The roof of the forest: trees in this layer form dense foliage, filtering rain and sunlight for the layers below
- Typically a height of around 20 metres tall
- Includes tawa and kohekohe
- Typically includes various tree ferns such as mamaku and ponga, nikau, and small trees such as māhoe, makomako, whauwhaupaku and tarata
- Plants in this layer often grow to about ten metres tall
- Often consists of ferns, young trees, shrubs and vines up to about five metres tall
- Can be very dense and hard to walk through
- Often includes kawakawa, karamū, rangiora and tūrepo
The forest floor
- Usually damp, but can dry out in summer
- Consists of ground covers such as grasses, sedges, ferns, mosses and fungi
- Home to a wide variety of invertebrates including wētā, snails and ngaokeoke
- Important hunting ground for birds such as toutouwai and tīeke, as well as pekapeka
Creating a situation in which these five forest layers can develop is a challenging task. Hardy plants tolerant of drought, sun and wind exposure can generally be planted and left to grow. Other species require various amounts of shelter and shade, but also some sunlight and care. Our general approach is to create seed sources for a wide range of plants native to the local area, along with suitable vegetation for their seed to fall into, and then allow nature to take over – with minimal ongoing intervention (for example, weed control).