Right Tree, Right Place, Right Price
Nelson City Council RTRP Task Force, June 2023
Vision
The hills of Nelson are clothed with thriving native forests, ringing with birdsong, humming with indigenous biodiversity, providing a multitude of ecosystem services to the local and broader community.
Our Concerns
As the Nature and Climate sub-group of the Nelson Tasman Climate Forum, we are particularly concerned about the impacts of climate change in our local region. In recent years, we have already experienced several significant adverse weather events that have severely impacted lives, livelihoods, infrastructure and the natural environment. These include ex tropical cyclones Fehi and Gita, the 2019 Pigeon Valley fire and the August 2022 severe rain event, with the direct and indirect costs to the community of such events running into tens of millions of dollars. As planetary warming increases beyond original predictions, the frequency and severity of such climate-mediated disasters will increase, costing us economically, socially and environmentally.
Our Proposal
Over the coming decade, convert the approximately 650 ha of production forest dominated by exotic species into permanent native forest to create a contiguous native cover from the Maitai to the Roding and beyond.
Benefits
A multitude of ecosystem services that pine plantations cannot provide:
- Restored cloak of Tane healing Papatūānuku, and restoring the mauri of the hills of Whakatū;
- Healthy and flourishing biodiversity – flora, fauna and microbial;
- Healthy and stable soils – no risk of erosion due to harvesting activities;
- Healthy waterways brimming with native species, maintaining excellent water quality over decades and restoring the health of The Haven and the Waimea Estuary;
- Attenuation of stream flows through more effective water retention, thereby decreasing the flood potential of high rainfall events and maintaining higher water flows during dry conditions;
- Permanent carbon sequestration with carbon stocks continuing to increase over time;
- Low fire risk;
- Reduced pest plant load and no wildings;
- Beautiful hill-scapes providing aesthetic benefits to locals and visitors, and for recreational pursuits;
- Healthy, resilient, connected ecosystems that moderate rather than exacerbate severe weather events.
Costs
Reports to NCC estimate the costs to revegetate the areas currently in plantations through regeneration and replanting are likely to be between $4.5 m (Forbes 2022) and $10 m (Clarke 2022). In reality, if all 650 ha were to be replanted, the cost is likely to be closer to $28 m, based on real costs for replanting similar areas in Tasman. This assumes a planting rate of 2,500 plants per hectare, costing $17.50 per plant, over 650 ha. The $17.50 includes the cost of the plant, guard, stakes, planting preparation, planting, maintenance and project management, but not pest animal control or infrastructure such as fences or tracks.
In some areas, natural regeneration processes may be sufficient to develop native-dominated cover, but reversion to a fully diverse forest community will take decades – centuries. And in areas with a long history of pine plantations, soil communities are less likely to be capable of supporting large-scale passive regeneration.
Although this cost of $28 m may seem high, it would be spread over at least 10 years, and once established, native forest communities would cost little to maintain, but would continue to provide the suite of benefits listed above. In fact, the re-connection of remnants and forest fragments across the hills is likely to significantly enhance the ecosystem benefits accruing from both the existing and the newly established native forest areas.
Alternative Funding Options
Voluntary C market
Provide the opportunity for interested parties to buy carbon offsets for their carbon footprint at the real cost, not the inadequate market price. It costs ~$3,500 to offset 1 t of C by planting 200 native trees and shrubs, a comparable cost to an airfare to Europe. If NCC could attract buyers for some of the 144 ha available for registration in the ETS, then the buyers could recoup the carbon credits gained through planting to offset their footprint. And it is a one-off cost to offset a carbon footprint by planting permanent forest species, assuming the footprint doesn’t increase over time.
Similarly, individuals may be willing to invest in herbivore and predator control to protect native forest areas as a carbon offset, claiming the increase carbon sequestration potential resulting from pest animal control (particularly herbivores) as an offset.
There is also potential for biodiversity credits to provide funding for native afforestation, once the credit scheme has been developed.
Revegetate Using Seed
Sowing seed directly on site, either by machinery, hand or drones, has the potential to kick-start forest restoration much more cheaply than replanting. By establishing a suite of pioneer species through direct seeding, NCC could make considerable savings. A field trial being undertaken this winter in Tasman will help quantify the potential cost savings.
Hidden and Avoided Costs
Continuing to grow exotic species on the Nelson hills risks some implicit costs that are infrequently addressed. These include the control of wilding conifers, which is very expensive. However, without control these conifers pose significant threats to areas of native biodiversity and potentially significant costs, e.g., through fire.
The risk of wild fires in areas dominated by wilding conifers and in exotic tree plantations will increase as the planet warms. A single significant wild fire could potentially cause $10 – 20+ m worth of damage, particularly if the fire encroaches on areas with dwellings and other infrastructure.
The risk of erosion, sedimentation and catastrophic flows of slash and logging debris from plantation forestry has been highlighted by recent adverse weather events in the North Island. Even with best practice forestry controls, harvesting increases the risk of unacceptable rates of erosion on the steep hillsides currently planted, resulting in increased sediment loads over several years in local waterways and in The Haven and the Waimea Estuary. If harvesting and the post-harvest period coincides with intense rainfall events, the potential for harm is much greater, and more costly.
With climate change increasing the likelihood of wild fires and intense rainfall events, it makes sense to convert hazardous pine plantations into lower risk native forests, which not only provide mitigation through carbon sequestration but also adaptation by increasing the resistance and resilience of the environment to these adverse climate impacts. This adaptation results in “avoided costs” in economic, social and ecological terms for the fires that do not break out and the flood damage that does not occur. Quantifying these avoided costs may be difficult but we posit that the cost of revegetating with native species is likely to be a fraction of these avoided costs over the coming decades.
Prepared by: Dr Fiona Ede, on behalf of the Nature and Climate group of the Nelson Tasman Climate Forum