Speeding up propagation and establishment of indigenous trees

10 January 2023

The commercial scale production and establishment of indigenous tree species is becoming a reality as tree species propagated in small paper pots survive and thrive. However, not all sites are favourable for tree establishment so it is critical to know if paper pots can be used to plant trees in harsher environments.

The goal of the Government to establish 300,000 ha of indigenous forests by 2035 is a contribution to the global effort to slow the rate of climate change, increase our forested areas and restore native biodiversity.

To meet these aspirations, the pressure is on nurseries to increase their production capacity and deliver highquality plant-stock into the  marketplace that can be relied on for cost-effective establishment in a range of growing conditions.

Funded by Te Uru Rākau – New Zealand Forest Service and in partnership with the Bay of Plenty Regional Council, Tipu Wai Trust and Treeline Native Nursery, Scion helped to establish six trials around Rotorua to determine if container type affected the survival of over 30 indigenous forest species.

The sites, established between 2020 and 2021, were of varying quality so that our scientists could determine the impact container type has when conditions are variable. By doing so, we could be confident in our support for container types and volumes that can help overcome the consequences, even where site quality is poor.

Tree survival in the industry standard polythene planter bags (1200 cm³ PB2) was found to provide no additional advantage to survival when compared to the smaller and much more sustainable 700 ml paper pot. In terms of plant survival, PB2 bags outperformed the paper pots on only the poorest establishment sites.

There are several economic benefits to reducing container size, such as reduced potting media costs, fewer trays and space within the nursery, as well as more efficient transportation and more efficient planting. Also, use of paper pots brings an environmental benefit by reducing plastic waste.

Using Scion’s recommendations, nurseries have the confidence that 12 common species, grown in 700 ml paper pots should establish well under a range of growing sites. Even smaller pots were equally successful for some species (5 cm diameter paper pots). Partners will benefit from easier, faster, and cheaper planting. The country also benefits as more trees are established, enhancing indigenous biodiversity and increasing carbon sequestration.

An akeake seedling with a robust root structure grown using paper pot technologies.