How the restoration project began
Dr David Norton, a professor at the University of Canterbury’s Te Kura Ngahere | School of Forestry, was contracted to prepare The Tiromoana Bush Restoration Management Plan in 2004. The Plan recommended:
- removing domestic grazing animals (sheep and cattle) and wild animals (red deer and pigs) to allow natural regeneration of the remnant indigenous forest areas and in pasture areas;
- restoration plantings to enhance connectivity between the existing remnant patches of bush and to reintroduce key plant species to support indigenous fauna;
- providing public access along a walkway through the site.
The Restoration Plan has been updated every five years and includes an annual work plan.
Vision
In 300-year’s time, Tiromoana Bush has been restored to a predominantly forest ecosystem (including coastal broadleaved, mixed podocarp-broadleaved and black beech forests) where dynamic natural processes occur with minimal human intervention, where the plants and animals typical of the Motunau Ecological District persist without threat of extinction, and where people visit for recreation and to appreciate the restored natural environment.
Keeping out predators and pests
Protection works began in 2004, when sheep and cattle were removed from the bush and fencing was upgraded. A 16-kilometre deer fence was subsequently built that together with intensive animal control has eradicated red deer and helped reduce pigs straying into the bush. These actions stopped animals damaging the bush, protected restoration plantings and allowed natural regeneration to occur.
Annual programme of restoration planting
Strategic restoration plantings are undertaken annually to increase the area of native forest and wetland vegetation, as well as providing nesting sites and food resources for native birds. Approximately 1 hectare of restoration planting takes place each year, with all plant species sourced either from Tiromoana Bush or from the southern part of the Motunau Ecological District. A key focus has been on enhancing linkages between existing areas of regenerating forest and re-establishing rare ecosystems, such as wetlands and coastal forest. Plantings have included seedlings from the remnant black beech forest, kahikatea, tōtara, ribbonwood, lacebark, tī kōuka, lemonwood, kōhūhū, ngaio, kānuka, mānuka, and five-finger.
Unwanted species must be removed
Annual weed control is undertaken focusing on species such as wilding conifers, willows, and old man’s beard that have the potential to smother native vegetation. Gorse and European broom are not controlled as they act as a nursery for native forest regeneration and the cost and potential damage associated with their control outweighs any biodiversity benefits. As the native plants become established and successfully compete for water, nutrients in the soil and light the gorse dies out and is replaced by native forest.
Monitoring is essential and important
Regular monitoring and photographing of vegetation and landscape, birds and animal pests over the last 15 years enables progress to be assessed. 177 native plants and 22 native bird species have been recorded, including four nationally threatened species and several regionally rare species. Examples of successful plantings include Kahikatea planted in 2006 around Kate Pond that are now 4-6 metres in height. Tōtara, planted on the fringe of the bush is becoming well established. Under the restoration canopy five-finger and ferns are naturally regenerating, while in the previously heavily grazed kānuka stands, a diversity of native plants are now flourishing.
Restoration is a long-term process
The initial phase of restoration of Tiromoana Bush is a 35-year long project that commenced in 2004. While the project has been successful, there are ongoing challenges with maintaining fencing to prevent deer and pigs from entering the bush, and also controlling invasive species such as wilding pines, and other weed seeds carried by winds. The natural regeneration processes appear to be favouring some native species, for example kānuka is being replaced by mahoe. The restoration management practices, such as opening up the canopy to allow more sunlight for seedlings, will continue for some years to ensure the bush regenerates into a diverse native canopy. However, it will take more than one hundred years before a mature podocarp dominated forest comparable to what might have been at Tiromoana Bush before clearance becomes re-established.
The wetlands benefit from the landfill
The existing natural wetlands in the lower Kate Valley have been greatly enhanced. The existing wetland area has expanded with the new 12-hectare Kate Pond wetland. At the landfill, rainwater and runoff is collected and filtered before being released into the Kate Stream that flows down the valley into Kate Pond. This stream used to dry up in summer, which meant the wetlands consequently dried up. By collecting and managing the water flow year round, Kate Pond and the natural Ella Ponds are no longer seasonal wetlands, but have grown in size and now support a wide variety of native species, such as harakeke/flax growing at the verges, and trees that like having their roots in damp soil. The wetlands are a habitat for birds including rare species such as the spotless crane.
Tiromoana Bush is protected in perpetuity
In July 2006, a QEII National Trust Open Space Covenant was gazetted on the title of the property, which provides protection for the bush irrespective of any change of future ownership. Tiromoana Bush is thereby protected for future generations.