Our Story

Native trees have long played a critical role in mitigating the effects of land degradation, providing shade and shelter for livestock, increasing carbon sequestration, and enhancing biodiversity and connectivity across landscapes throughout New Zealand.

However, the cost and time involved to plant a native forest is a limiting factor for many landowners, especially when compared to the cost and returns of exotic forests.


Now imagine a technology that could sow native seeds directly into the ground, creating within a few hours of effort the makings of a potential future native forest.


Development of such technology has been underway over the last five years of selected New Zealand natives in the lower South Island.


In 2017 the Department of Conservation (DOC) purchased a direct seeding machine and started trials to explore more cost-effective solutions for large-scale restoration of native plants. And now, the team at Seed NZ Natives is continuing to drive that work.

NZ’s first Burford Tree Seeder near Wanaka. Photo: Toby Jones

The Burford is Born

DOC chose a proven technology from Australia to trial the direct drilling of NZ native seeds. Designed in South Australia in the late 1980s, the Burford Tree Seeder was developed to address rapidly growing land degradation issues such as erosion, salinity, deforestation, and vegetation fragmentation. Burford Tree Seeders are used extensively across Australia in some of their most challenging environments.

The future of seeding? This is a 15 year old direct seeded paddock in Australia which had livestock returned 5 years after seeding. Photo: Sue Streatfield

Superseeding

To fully appreciate the Burford’s value in restoring landscapes, it is important to understand what it, pardon the pun, ‘superseded’.

Traditional native plant restoration often involves the planting of nursery-raised seedlings, which is generally expensive, labour intensive and prone to varying plant survival rates. The Burford was custom made for the sole purpose of sowing the seeds of native trees and shrubs directly into the ground with the original design barely changing in over 30 years.

In New Zealand, direct seeding trials using the Burford Seeder were undertaken by a small team within DOC across multiple sites, properties and landscapes in Canterbury, Otago and Southland. Each of the 20+ sites were selected to test vastly different and diverse environments, ranging from pasture competition, bone dry conditions, waterlogging, and pest invasions.

The direct seeding trials were designed to test the machine with a range of NZ species, conditions and landscapes to formulate a recipe for success. This included how best to prepare sites, collect and process seed, and adapt and refine the direct seeding methods and maintenance to NZ conditions.

Seeding Te Anau

Trial lessons and results

Samples of seeds collected for each site were germinated to determine the viability of each species in controlled nursery conditions. This was to provide an assurance that seed sown in the field was viable. The germination rates mirrored closely those in the field, suggesting that seed viability, rather than the delivery, plays a significant role in success.

A seed batch 4 months after germination tests

The seeding by the Burford Seeder across the field trial sites was monitored for species survival, densities, and growth rates. Results across all sites varied and many lessons were learnt. Germination of several species was achieved across most sites, however, several sites failed due to external factors, such as livestock, pests, or drought. Other sites with high rainfall and fertility became overwhelmed by pasture competition.

Please Release Me!

Post emergent herbicide treatment for the first 2+ years proved to be one of the most crucial interventions for the key to success. Seedlings will need timely release spraying to liberate them following the flush of spring and summer growth. Only a few native species were lost due to intolerance to the herbicide formulations used.

The highest performing species for prevalence, germination and growth include manuka, kanuka, flax, cabbage tree, pittosporum and hebe.

These species are commonly used in revegetation programmes to provide an early successional cover of native forest.

It takes between 2.5 to 3 years from time of seeding for plants to outcompete the weed and grass competition.

Full Seed Ahead

The Burford direct seeding trials in the southern parts of the South Island have to date achieved successful germination and early recruitment of a range of native tree species that indicate large scale restoration on land of drivable contour, can be achieved at a fraction of the cost of planting nursery-raised stock.