Special Feature: Bioenergy
All in a day’s work
Story: Jim Childerstone
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T’S AN INTERESTING TIME TO BE INVOLVED in the sectors of bioenergy, land use, biodiversity and carbon. From contracts in the Auckland region to advising on chip fuel boilers in Southland, Ahika Consulting is flat out keeping up with work. In one recent project in the Lake Pukaki area, Ahika has been assisting Pukaki Forestry to create a biomass business model using 1,200 hectares of wilding forest. The model being proposed is to harvest wilding trees and generate income via log sales while creating a secondary biomass product from the residues. Ahika director, LLoyd McGinty, explains, “Our proposal will assist offsetting the ongoing costs associated with wilding control. “Timber is a valuable product, so highquality logs will be sold into the timber market while the residue from harvesting will be sold into the biomass energy market.” This includes all slash and logs SED <12cm. One challenge is that due to the location and distance from biomass markets, transport becomes a significant cost. “However, to offset this cost, biomass logs will be stacked on site during harvesting and air-dried for the purpose of adding value,” says Lloyd. “Wilding forests are unlike any other type of forest. For example, a typical plantation forest will be thinned to 280 sph while a wilding forest can have more than 3000 sph. Because of this, it is difficult to estimate the volumes that would be expected from this type of forest,” he explains. The trial started in early August 2020 and will assess the volumes of merchantable logs, biomass logs and slash from different age class forest blocks. “It will evaluate harvesting costs and measure the effectiveness of natural drying in the Mackenzie Country,” says Lloyd. The trial has Environmental Canterbury support. In another recent trial with the Canterbury Woodchip Company’s Morbark chipper, capable of chipping or hogging 100 M3/hr, it flattened a 4ha. stand of mixed age contorta pine within 12 hours. Although post timber could have been extracted, the chips were blown over the area covering about 100mm ready to be replanted in native wood or the hybrid Attenuata Cedrus – also being trialled at nearby Pukaki Downs Station.
42 NZ LOGGER | May 2021
Ahika headquarters staff at the Dunedin HQ. The rest are working on sites in both the North and South Islands, involved with both wood-based biofuels and replanting experimental sites with native and exotic trees and shrubs. Top from left: Lloyd McGinty, Rhys Millar and Mike Thorson (Director, Biodiversity). Bottom from left: Niki Bould (sustainability), Sharon Teavae (chief organiser), SarahWright (ecology) and Ray Morgan (carbon and energy). (See December/January edition of NZ Logger for more on this trial). Talk of native reforestation, the firm’s co director, Rhys Millar, is fully involved with landscape-scale restoration of the Hunua Forest Restoration project. Helped by team mate, James Tweed, the pair have been working on the policy, advice and strategy since 2016. Rhys explains the majority of Auckland’s water supply is sourced from reservoirs in the 17,500 ha Hunua Ranges – Auckland’s largest mainland tract of regenerating and mature indigenous forest. “Within the Hunua Ranges there is approximately 2,300ha of exotic forest that is managed for timber production under forestry right. The aim is to restore this area (post-harvest) of pinus radiata forest back into native forest, and in doing so, protect and enhance the water quality so that Aucklanders can have secure, highquality water,” he says. Essentially the goal is to successfully achieve a large-scale forest restoration project for the purposes of creating secure high quality water for Aucklanders.” In doing so the aim is to provide a significant area of managed biodiversity that is contiguous
with Hunua Regional Park. “In time, this will provide large areas of habitat for threatened species. It is anticipated that area will become a part of a network of recreational trails, linking Auckland to the Coromandel and beyond,” Rhys says. “We are monitoring the operations and resultant success of the different management techniques being used to achieve native forest cover.” He hopes the learnings from the project will be applicable across other forest restoration projects elsewhere in New Zealand. LLoyd explains that planting natives can be costly – from $15,000 to $20,000 per hectare and registered for carbon uptake. But in the longer term carbon credits could pay off establishment costs. Natives, he says, are long term, “very long term”. Current value under the ETS is just under $40/t sequestration. Predictions are that values could reach $70/t which could provide a net return. Up in the Lakes District the firm is involved with the 55,000 ha Mount Soho QE2 Trust to establish native beech and manuka where practical on land between
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