The goal includes having 200 million native trees planted by 2028.
However, a survey commissioned by the Forests Ministry survey indicates only 160m native seedlings can be supplied by then.
That is based on a sustainable growth rate of 7.5% a year for a sector that has had 12-15% growth for the past three years but that has been described unsustainable over any length of time.
But Plant Producers spokesman Martin Craig said despite the predicted shortfall the survey reveals a glass-half-full scenario for a sector with good growth prospects over a considerable time.
“We think demand for native plants is going to continue, regardless of government policy.
“That demand is coming from greater riparian plantings, more community planting projects and significant road project plantings like Transmission Gully and the Waikato Expressway.”
Government announcements of a further $6.8b for roads will only add to the certainty of demand for even more native plantings.
Native trees eligible for the Billion Trees programme accounted for a quarter of the 40m native plant seedlings grown last year.
They covered 9000 hectares of new native plantings. The rest were largely flaxes, grasses and shrubs.
Craig said the high proportion of native grasses and shrubs provides nursery owners with a more rapidly maturing stock that is ready for sale after only a year and can support nursery businesses also holding stock of slower-maturing tree seedlings.
The sector’s ability to expand faster to meet future demand is most constrained by skill levels.
“The skill you may have in raising exotics is not necessarily transferable to natives.
“Operators tend to guard their skills quite closely and have often developed them over a long period of time.”
So far there is no specific training course in native seedling skills but the sector is examining its options and how it can integrate with proposed changes in the polytech training system.
Ownership of seedling rearing businesses in New Zealand tends to be concentrated around large businesses that comprise only 5% of total operators but grow half of the natives.
“Because of the more limited number of native plants used in the likes of roadside plantings there is the opportunity there to automate the process, which requires more capital.”
The industry hopes, with further work, it can present banks with a viable case for why native nursery operations are worth financing, given the projected future demand.
The longer lead times of two to four years for growing out natives suitable for farm and forestry plantings mean operators need to plan well ahead.
“You also need to ensure you match your seed stock to the area you will be planting in so you match your plantings to the sub-species in that particular area.”