Retiring erodible hill country: carbon forestry, mānuka or status quo

Carbon forestry as offered. Upfront payment 90 × $5,000 = $450,000. Against that, the farm forgoes $38,000/yr of gross margin, roughly $1.14 million over 30 years undiscounted, so the headline payment covers about 12 years of margin. Crucially, the company retains the credits. At 20 tCO2e/ha/yr × 90 ha × $60, that is $108,000/yr of carbon value going to the company, not the landowner, for 30 years. That is the key asymmetry in the deal.

Alternative: register in the ETS yourself. Similar establishment cost (roughly $1,200/ha, about $108,000) but the credits accrue to the landowner, subject to the liabilities: the forest must be maintained, and credits must be repaid or the forest re-established if it is damaged by fire, wind or disease. On steep erodible land, clear-fell harvest is also a real liability - slash damage is exactly the mechanism that caused the track and culvert damage last winter.

Mānuka. Potentially high value per hectare for honey, but establishment cost, five to eight years to meaningful yield, uncertain UMF grading, and myrtle rust risk make it speculative. It also locks the land up just as completely as pine.

Native reversion. Low cost, strong erosion and biodiversity outcome, modest carbon returns and no harvest liability, but effectively no income for decades.

Poplar and willow. Cheap, proven for slope stability, retains grazing, but generates no carbon income.

Recommendation. A hybrid: retire the worst 40–50 ha with native reversion and spaced poplars for erosion control, and consider pine only on the remainder if and only if the landowner captures the carbon credits and the harvest liability is priced. The offered deal transfers the most valuable part of the asset to the counterparty.

Stock numbers. At roughly 7 stock units/ha, 90 ha carries about 630 SU. At about 3 SU per ewe, that is around 210 ewes, so the flock falls from 2,450 to roughly 2,240, or cattle numbers are reduced accordingly.

Feed and the winter crop. The retired block is the summer and drought buffer and the main rising two-tooth grazing. Removing it means either buying in supplement, expanding the 25 ha winter crop onto easier land, or accepting lower performance. Expanding the winter crop increases nitrogen loss and cultivation on land that is more productive but also more visible, so there is a compliance cost as well as a feed cost.

Financial offset. The $450,000, if applied to debt at 7%, saves about $31,500/yr in interest. That offsets most of the $38,000 gross margin forgone, so the true annual cost of the deal is around $6,500 plus the loss of the drought buffer. That is a much better picture than the headline suggests - and it also shows why the deal's value depends heavily on what is done with the cash.

Labour and infrastructure. Trees need little labour after establishment, so the effective labour requirement of the remaining farm falls slightly, but the remaining system is more intensive per hectare. Fences, tracks and water in the retired block must be either maintained for fire access or decommissioned and the cost budgeted.

Second-order effects. Fewer stock means less flexibility in a drought, tighter grazing rotation in summer, and possible difficulty meeting contract volumes. It also changes the farm's greenhouse gas profile, which may matter under future pricing. The decision should be made on the whole system, not on the 90 ha in isolation.

Fire. East Coast hill country is dry, and a young pine block is highly flammable. If the forest burns, the landowner faces replanting and, under the ETS, repayment of credits already claimed. The company contract must be read for who carries that liability; the answer is usually the landowner.

Harvest and slash. Clear-felling steep class 7e land is exactly the situation that produced the culvert and track damage last winter. Harvest may be restricted, uneconomic to access, or politically untenable after a severe weather event. The trees may become unharvestable, in which case the landowner has a permanent forest, not a crop.

Wilding pines. Radiata on erodible hill country spreads. Wilding control is a long-term cost and a neighbour relations problem.

Biological risk. Mānuka carries myrtle rust exposure, and pine carries disease and wind risk. A single-species plantation concentrates risk.

Contract and counterparty risk. A 30-year contract with a company that may be sold or fail is a long exposure. Who holds the credits, who pays rates, who controls harvest timing, and what happens on default all need to be explicit.

Social licence and kaitiakitanga. The catchment group is asking for erosion control, not plantation forestry. Converting erodible land to pines may be read locally as land abandonment, and relationships with neighbours and the catchment group have real value in a rural business.

Optionality. Thirty years is a long lock-up. It forecloses horticulture, subdivision, or a future higher carbon price. A decision that is right at $60/t may look poor at $150/t or at $25/t.

A defensible answer weighs erosion outcomes and optionality, not just the carbon arithmetic.