Ecological restoration is the process of reestablishing a self-sustaining habitat or ecosystem similar to what is likely to have existed before human contact. The restoration could involve the reintroduction of native fauna and flora, and the eradication or control of pests.
When reintroducing plant species, the aim should be:
- To restore to a site those genes and species which, if it were not for human intervention, might be expected to be naturally found there;
- To establish plants in the appropriate landscape, in a way that replicates natural dispersal patterns (this is especially important where species are planted in a natural setting and are intended, or have the potential, to naturally regenerate).
In the highly modified Waikato landscape where native plant populations are diminished and fragmented, it may not be possible to recreate exactly what was once there. Some species may not be readily available or difficult to propagate.
However we should do everything possible to try and keep the natural character of the local vegetation. Therefore ecosourcing is a crucial element of local restoration, and is supported by the New Zealand Biodiversity Strategy.
Ecosourced Waikato (a group representing plant growers, the Department of Conservation and local and regional authorities) has developed native plant lists for different habitat types in the Waikato District. Funding support was provided by the Waikato District Council as well as the Department of Conservation with considerable input from Wayne Bennett of Forest Flora.
The lists are designed to assist ecological restoration in the Waikato They are not intended to be a comprehensive description of the primeval forests/wetlands/vegetation of habitats. They should be viewed as a simplified recipe for the reconstruction of natural patterns and processes, based on the experience of plant growers involved in ecological restoration.
Ecological restoration is not usually a one-off activity. It may require a number of interventions in order to restore natural patterns and processes. Restoring less common species may require specialist advice.
Any suggestions for corrections or improvements to these lists should be emailed to email@example.com.
The Lower Waikato River
The Waikato River has developed an entrenched course as it flows through the Hamilton Basin on its way north. At Ngaruawahia it is joined by its main tributary, the Waipa River, before continuing north to Mercer and then turning west to reach the sea at Port Waikato
Along the stretch of river from just south of Hamilton out to the sea, a number of landforms have evolved, from ignimbrite cliffs, steep pumice banks, river terraces, back swamps, islands, tidal waters and saltmarsh. This variation in landform means a variation in the composition of the vegetation. For this reason, the planting lists cover different sections of the river and within each section there are a number of different zones.
1. River mouth to Tuakau Bridge
The section of river from Port Waikato to the Tuakau Bridge includes four distinctive zones:
- Tidal saltmarsh
- Low islands and river margins
- Steep river banks
- Back swamp
2. Tuakau Bridge to Ngaruawahia
This section of the river is prone to flooding, with winter flood levels likely to be several metres above summer levels every year, often for long periods at a time. This regime eliminates flood intolerant species from a large area of riverbank and shortens the growing season. The zones are:
- Sloping river banks
- Back swamp
3. Ngaruawahia to Tamahere
This section of the river from Ngaruawahia to just south of Hamilton city has a mix of landforms from steep ignimbrite cliffs to sandy/pumice river terraces with numerous springs and seeps. Three zones are recognised:
- Ignimbrite cliffs
- River terraces above flood level
- Annually flooded lower riverbank
The Lower Waipa River
The Waipa River enters the Waikato River at Ngaruawahia, cutting through deep pumice soils deposited when the Waikato River flowed over the same landscape many years before.
4. Whatawhata to Ngaruawahia
The planting guide covers these zones:
- Steep pumice banks
- Permanent wetlands
The peat lakes of the Hamilton Basin formed where sand and gravel from the Waikato River blocked valleys. Subsequently, thick peat has developed around them.
Horsham Downs Peat Lakes
Peat lake margins have low fertility waterlogged soils supporting a low stature plant community. Further back from the lake edge, the mineralised zone at the foot of low hills supports a tall, many layered forest dominated by kahikatea.
Lake Rotokauri is situated on the edge of Hamilton city and although there are increasing amounts of urban development in the area, there is still some natural vegetation with potential for restoration. The lake margins would have originally been of low fertility but changing land use in the surrounding catchment has tended to raise nutrient levels. This now presents challenges in terms of reestablishing low fertility plant.
The rich alluvial floodplains of the Hamilton Basin have largely been cleared of forest for farming but there are still some small remnant stands dominated by kahikata scattered across it. Many remnants are located in areas that have been extensively drained so the choice of plants for restoration purposes needs to be based on whether the ground is now predominantly wet or dry.
A number of riverine lakes are found north of Huntly between the western coastal hills and the Taupiri and Hapuakohe Ranges. The margins of these lakes are swampy, being fed by river water rather than the peat forming margins normally associated with lakes in the Hamilton Basin.
That part of the Waikato District situated between the Waikato River and the Tasman Sea is largely rolling hill country, bounded by the Hakarimata Range in the south east and the coastal settlement of Raglan and the Karioi coastline in the south west, up to Port Waikato in the north. Inter-dispersed amongst these hills are areas of low-lying land and alluvial valley floors, sometime seasonally flooded and in places, swampy. Lakes Whangape, Rotongaro and Waahi and associated wetlands are found in this area.
This planting guide covers seven distinct zones:
- Hillslopes (rimu-tawa forest)
- Leached ridges (kauri – hard beech forest)
- North western taraire forest
- Karst landscapes
- Steep rocky streams
- Kahikatea dominated margins of gully, stream, wetland and rivers
This planting guide covers five zones:
- Coastal Te Akau
- Whaingaroa Harbour shore
- Karioi coast – exposed coastal headlands
- Karioi coast – steep cliffs
A series of ranges and rolling hill country dissected by broad alluvial valleys lies east of the Waikato River from Taupiri north to Mangatangi. Sandwiched in between are Lakes Waikare, Ohinewai, Kimihia and Hakanoa and their associated wetlands.
The planting guide covers three distinct landscape features:
- Ranges and hills
- Valleys and water margins
For further advice or information about ecosourcing or native restoration projects in Waikato, contact:
|Kirikiriroa / Hamilton Office|
|Phone:||+64 7 858 1000|
|Fax:||+64 4 471 1117|
73 Rostrevor Street
Private Bag 3072
|Full office details|
Phone: +64 21 274 2132
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