The Scion project has helped shift the economics of native seedling establishment.
A One Billion Trees-funded project provided the impetus to boost Scion’s research efforts to learn how New Zealand could plant more natives, quickly. Richard Rennie spoke to Scion tree geneticist Dr Heidi Dungey and her research team on how some simple solutions will help hit a big planting target.
The irony that native tree planting creates a landfill’s worth of plastic waste has not been lost on Dr Heidi Dungey and fellow researchers Craig Ford and Alexander Lloyd at Scion. This has partly driven their efforts to seek out a large-scale, streamlined approach to germinating and propagating native seedlings and ramp up industry planting capacity.
“Typically, natives would be raised in a 1.2-litre polyethylene bag container (PB2) prior to planting. When you look at efforts to plant 120 million natives, that is a lot of plastic waste being generated,” Ford said.
The conventional approach of sowing native seed, pricking out and then growing in containers takes 12-36 months, adding significantly to natives’ establishment costs over exotics.
“We decided to take some of our exotic seedling experience where they only take 9-12 months to grow out and try it with natives,” he said.
The work has been enabled thanks to partners including Te Uru Rākau–New Zealand Forest Service and collaborators Bay of Plenty Regional Council, Minginui Nursery and Tipu Wai Trust.
The researchers identified a number of bottlenecks to native propagation, including seed availability, slow propagation cycle, labour and tree establishment limitations.
Taking the paper pots exotics are grown in, and which are a 10th of the natives’ PB2 size, they have found a simple but vital solution to accelerating the process.
The Ellepot paper “Ellebags” and “Ellepots” are made using specialised machines and degradable paper to form the container shape for placing the seed or seedlings in.
Results based on six trial sites around Rotorua show on average a 90% plastic waste reduction and a 50% saving on seedling medium mix, with highly positive tree growth outcomes, when using the Ellebags or Ellepots.
Many of the species trialled were proven to grow very successfully in Ellepots as small as 125-310ml.
“And from a practical and ergonomic point of view, that is a considerably greater number of pots someone planting in the field is capable of carrying than the 1.2-litre plastic bags,” he said.
In an industry strapped for labour supply, the savings using the paper pot machine are between $30,000 and $90,000 a year for a one million seedling nursery.
The technology has already been picked up by three native plant nurseries and more are expected as the impetus to plant natives as permanent sequestration forests grows.
Survivability is proven to be at least that of the plastic option, at over 90% and in some cases seedlings in mid-sized 700ml paper Ellebags did better than the bigger plastic option.
The research has also alerted researchers to other propagation means, with some species performing very well when established from simple cuttings.
“We are wanting to challenge the paradigms on how fast you can grow out natives and get them started in the field. If you use the knowledge gained from exotic forestry practices, you can reduce the growing time. Success also improves when you use expert planters in the field rather than volunteers,” Dungey said.
The top six species exhibiting survivability rates of 90-97% included kānuka, akeake, tōtara and ribbonwood, often pioneer-type species in regenerating bush canopies.
The work is also looking to determine the right combination of native plantings for the right end-use, whether it is carbon sequestration, plantation or remediation.
“Ultimately we would like to have a series of demonstration forests to show landowners the outcomes and options,” she said.
Ford said the researchers hope more knowledge of planting combinations, their ideal locations, coupled with the smaller degradable paper pots will bring down the cost of native seedlings.
Ultimately, he would like to see native nurseries have the potential to double crop over 12 months, significantly slicing time and production costs down to commercially realistic timeframes.
Establishment costs and time to maturity are big brakes on native plantings, with the Scion researchers putting current native costs at between $10,000 and $50,000 a hectare.
That compares with about $1500-$5000 a hectare for exotics, which ETS data suggests sequesters about six times more carbon in their first 28 years.
“But Pinus radiata also has about 75 years of research behind it, we have not had anything like that for natives,” Dungey said.
