Estuary planting project under way
28ha of native forest has been planted across nine farms
Amammoth native planting effort has taken place in one of the Bay’s most polluted catchments to retire marginal grazing land and help protect sensitive waterways.
A total of 28ha of native forest has been planted across nine farms within the Waih¯ı catchment, which runs from the mountains near Lake Rotoiti and Rotoehu to the coastal estuary at Pukehina.
The planting took place on properties that have Environmental Programme Agreements with Bay of Plenty Regional Council and was cofunded and co-ordinated by Wai Ko¯ kopu. The project is also doubling as a large-scale trial of forestry-grade native planting in the catchment which may substantially reduce the cost for farmers to retire marginal or unprofitable grazing land.
Wai Ko¯ kopu’s restoration manager Tom Anderson says Waih¯ı Estuary was once a main food bowl for the Bay of Plenty but is now considered one of the most polluted in New Zealand.
“Shellfish gathering was regularly undertaken, but is now generally unsafe because of the state of the estuary. The rivers feeding the estuary are also not safe to swim in. Overall, because of high levels of nitrogen, phosphorus and E. coli, the estuary’s entire ecosystem has been compromised with many native plants, fish and birdlife struggling to survive.”
Wai Ko¯ kopu’s restoration team has planted 62,750 forestry-grade native plants across erosion-prone gully heads, steep hillsides and wetlands in recent weeks. Forestry-grade seedlings are similar to pine seedlings. They have substantially less soil around their roots, making them cheaper and more efficient to plant.
“By applying large-scale forestry techniques to native planting, we are aiming to lower the cost of native establishment, helping landowners’ and funders’ dollars go further,” says Tom.
“Other successful projects around the country using this method have shown that forestry-grade native plants can more than halve the cost of conventional native establishment to between $5000 to $12,000 per hectare. We hope to replicate these strong survival rates in this trial.”
Anderson says both animal and weed pest control is essential to successful long-term native establishment.
“Diligent pest plant control from weeds like blackberry, Japanese honeysuckle, kikuyu grass, Taiwanese cherry, climbing asparagus and tradescantia, both before and after planting, is critical to success irrespective of whether forestrygrade or larger plants are used. Pest animal control was carried out prior to planting, targeting wallabies, deer and hares. These plants will be regularly checked for evidence of browsing, and further night shooting will be carried out if required.”
The forestry-grade native seedlings cost less than $2.20 for each plant and planting, whereas larger grade plants cost up to $6 to grow and plant in the ground. At 2500 stems per ha, Tom says that is a cost difference of $5500 per ha compared to $15,000 per ha. Bay of Plenty Regional Council paid for approximately half the cost, with remaining funds coming from landowners and Wai Ko¯kopu which is funded by Baytrust and TECT.
Local farmer John Burke and his son, James, were eager to take part in Wai Ko¯kopu’s latest project and retired 2.64ha of riparian land by planting 6600 native seedlings.
John believes the forestry-grade seedlings will establish well over time, having retired land using this method on his farm in Kaitkati and other challenging sites around New Zealand over the last 10 years.
“We’re confident that, with the right management, it will be successful. It’s not going to be something that you have an instant native bush overnight but within five or six years we’ll have full canopy closure.”
Planting traditional higher-grade native plants at higher densities can be very costly for farmers and a barrier to ecological restoration, John says.
“We’re really keen to restore, where possible, those ecological corridors and those boggy wet areas that aren’t really producing much grass. They’re barely profitable from a pastoral enterprise point of view so they’re better to be retired back into native bush. You’ve then got the additional benefit of reducing contaminants getting into the waterways, improved ecology, aesthetic value and potential earnings from carbon.
“We’ve got a degraded catchment and as farmers we’re looking to do what we can on our footprint of land which will contribute to meeting the vision for Wai Ko¯kopu.”
The community-led programme aims to replenish and revitalise the Waih¯ı Estuary by restoring the ecological health of the 34,000ha catchment’s three main rivers and streams — Kaiko¯kopu, Wha¯rere and Po¯ ngakawa.
Retiring marginal land, riparian strips and wetlands is a key component of that.
A diverse species mix was used during the recent planting project. Around 60 per cent of plants were ma¯nuka and ka¯nuka, with the remaining 40 per cent made up of karamu, kohuhu, tarata, mahoe, whauwhaupau (five finger), makomako (wineberry), harakeke (flax), and ti kouka (cabbage tree). A total of 2500 plants were planted per hectare at a 2 x 2m spacing, with each planter able to plant around 1000 trees per day.