Massey University’s Dr James Millner says planting native trees could provide a means to not only sequester carbon, but also a valuable feed reserve in times of feed shortages.
In a case of “sequestering your carbon while eating it too”, Massey researchers are exploring some alternatives to typical approaches in farm carbon offsetting. Massey University’s school of agriculture and environment dean Dr James Millner outlined early trial results to Richard Rennie.
Planting trees, both exotic and native, on tougher parts of hill country farms has been heavily touted as an option to not only capitalise on the rising carbon market, but also a means to reduce erosion losses.
Recent work by Massey University researchers has revealed native plantings may also provide a third string to this bow by providing a valuable feed source in years when pasture growth succumbs to drought.
The researchers have been trialling some native species planted on tough east coast hill country that offer some feed value once established. The trial has been funded as part of the Ministry of Business, Innovation and Employment (MBIE) and Beef + Lamb NZ’s hill country futures programme.
The project targeted the toughest 10% of a 564ha property and planted it in native shrubs for a five-year study period. The plantings reduced the property’s ewe flock by 290.
“Really what we were wanting to do was to verify that if you had a stand of these shrubs there is potentially some feed value there,” Millner said.
“It’s not going to be a significant contributor, but in a dry summer you could get value putting ewes onto them. It would be an opportunistic use of the area and you would not want to put too much pressure on the plants.”
The native shrubs that appear to have the greatest potential are papauma, or NZ broadleaf.
“In terms of taste preference, we know it gets hammered by possums, goats and deer, the leaves are pretty good feed,” he said.
The researchers have also studied the potential greenhouse gas production of the particular plants and biomass, or carbon reserves, they are capable of generating.
“Measuring for methane production, all we know at this stage is that they are quite similar in terms of production to pasture,” he said.
Typically, native plantings face high upfront costs to establish, with estimates as high as $20,000 a hectare on tough country, compared to as low as $4000 a hectare for pines.
“And we are pretty much mandated by the look-up tables as to their sequestration ability, which is significantly lower than pines,” he said.
Typically, a newly planted native forest area will take 100 years to overtake the carbon stored by planting pines on the same area.
But Millner says some varieties of the natives the researchers have been working with displayed remarkably rapid growth rates as first-generation native forest species, with the native taupata growing two metres in the first two years of the project.
He also acknowledges the challenges that go with such native plantings, not least the level of pest control required.
“We had another site on the go up at Mahia but we lost that to the goats. Wherever there are goats, you can face a real challenge getting these established,” he said.
The expense of establishment should not be underestimated, and the east coast property’s 10% area is to be planted out at a rate of 20% a year over five years to stagger the cost.
“Even then, it remains a pretty big project,” he said.
The researchers feel confident the plants are livestock-friendly for quality and safe eating.
In the meantime, they offer relatively rapid establishment on steep erosion-prone country.
“And down the track if hill country farmers are required to act on sediment loss and biodiversity, there will be credits from these plantings in these aspects too,” he said.
Early economic modelling against carbon values indicates at $65 a tonne, native shrub planting was marginally infeasible and becomes feasible at $71 a unit.
Latest carbon values have hit $68/t, with 2026 prices locked in at $80 a unit. The analysis also did not take into account the amenity value or value in erosion reduction.
Further research work will examine animal feed preferences more closely and also examine the practicalities of incorporating pine trees into mixed planting scenarios.
Coming from the Taihape district, Millner says he contemplates with deepening concern the rapid recurrence of droughts in that region and on the East Coast.
He says that should be giving more farmers pause for thought about the role forestry could play in ensuring they can continue to farm well into the future.
“Hill country farming is pretty marginal at the best of times and now we face a succession of droughts that never used to happen,” he said.
