By Sue Streatfield, Partnerships Ranger
If you saw our last blog posts you’d know that we purchased a Burford direct seeding machine in 2017 to trial the direct drilling of native seeds in the Southern South Island.
It’s part of our quest to develop cost effective solutions to native plant restoration across the country and has implications for the One Billion Trees programme, manuka honey industry, riparian restoration and our efforts to restore conservation on farms.
Where are we at?
In Spring 2018 we included another 7 trail sites to our growing green portfolio.
All these sites are part of the Waiau Fisheries and Wildlife Habitat Enhancement Trust which has been supporting wetland and stream protection and extension in the catchment for over 20 years.
Five of the sites are Landcorp properties in the Te Anau Basin with a further two wetland sites in Southland owned and managed by the Trust.
Seeding was undertaken in mid-October and initial monitoring undertaken in early December. Encouragingly all sites had initial germination primarily of pittosporum, flax, cabbage tree, broadleaf and mānuka.
Of the 10 sites, we measured the lowest average at 1.66 and the highest average at 7.26 seedlings per metre. Our original aim was to establish one plant per metre, so this is more than encouraging.
We’ve also revisited many of our sites from 2017 and were delighted to discover that, despite early concerns, our 3 trial sites around Alexandra have between 3.6 to 5.2 plants per metre.
As predicted the winter encouraged germination of those species dependent on cold stratification – a process where seeds need both cold and moist conditions. This process could mean that Autumn, rather than Spring has been identified as the preferred seeding season in New Zealand.
The site at Waituna also proved surprising with the original seedlings still healthy and growing despite being overwhelmed with competition. They’re all there, just hiding…. temporarily.
If only 10% of these survived, the overall result would be more than satisfactory. Competition from weeds in these fertile lowlands continues to be a challenge so we are trialling some selective post-treatment herbicides.
So far, we have had germination of mānuka, kanuka, pittosporum, broadleaf, hebe, flax, cabbage tree, coprosma, corokia, ozothamnus, Olearia and kōwhai. Further trials will continue this Autumn on most of the Wsites and we will continue to monitor progress as we reach the 18 month milestone this Autumn.
We believe it will take two years from time of seeding to fully determine success, so Spring this year and next will be a crucial for the future of the Burford seeding machine in New Zealand.
What have we learnt?
This Aussie Burford battler is adapting and performing well in its new environment. The machine has been thrown some trying physical conditions including sizable rocks, extreme wet and bone dry conditions. It’s a tried and true performer which is why it was chosen.
The machine delivers both small and large seed types as intended to maximise germination. We know this because germination trials done in greenhouses at Otago Corrections continue to show results similar to those in the field. This suggests that viability and timing rather than delivery is a defining factor in germination. The machine is consistent, the operator is consistent and the seed flows freely.
Our greatest knowledge gap relates to the seed biology. Specifically, how to treat, store and process the seed to maximise germination. Some seeds, such as coprosma, need cold moist stratification, so either refrigeration or an actual winter to prompt germination. Other species depend on the presence of mycorrhizal fungi to survive in the long term.
What types of fungi and how best to collect and then inoculate the seeds are just part of the problem. Fortunately, we have the Botany Department at the University of Otago and QEII asking the same questions and helping to solve some of these gnarly questions with research projects happening this year. In 2018 most of the seed was collected and treated by Home Creek nursery with 30 years’ experience in collecting, storing and processing seed.
Lucky for us, getting seed to germinate is their bread and butter.
You can never do enough site preparation. Removing the competition in the early stages of germination and growth is vital. Getting early succession species up and ahead of the competition equates to a race against time.
Recent monitoring of 1 year old direct seeding has shown that even when the competition threatens to overwhelm, the seedlings are big and strong enough to survive the onslaught.
Committed land managers and partners are vital.They can help undertake fencing, seed collection, seed processing and site preparation. Plus, they’re there to share the hope, frustrations, concerns and celebrations.
The machine is only a part of the equation and one in a long line of activities starting with site selection and seed collection all the way through to monitoring and evaluation
Success has many fathers, but failure is an orphan. Innovation requires persistent problem solving, constant risk taking, endless optimism and a willingness to join the orphanage. Spring 2018 has been most promising, but it hasn’t been all smooth sailing with 2017 throwing up many challenges including rogue sheep, hare plagues and one of the hottest, driest summers on record in many southern parts of the country.
So where to in 2019?
We hope to extend our trial sites to the Mackenzie Basin, and as mentioned, further explore Autumn sowing and continue monitoring of all sites established since 2017.
We also plan to submit a peer reviewed, technical paper documenting our journey and findings. Above all else, we will continue to work with key partners to investigate, promote and advocate for direct seeding and other cost-effective forms of re-vegetation in New Zealand.
It has been, and will continue to be, full seed ahead!