It created quite an impression, not least of all with the owner.
Three neighbouring, perfectly sound indigenous plants were summarily dug out of the ground, after being happily established there those last eight months.
Had the plants been dead or dying, no qualms would have been felt.
It is instructive that field day attendees were somewhat shocked—the sanctity of an indigenous species had been violated!
But by the simple expedient of actually investigating how well or otherwise the roots of plants had established into the surrounding ground, more was revealed in minutes than would have been in a lifetime of exhuming dead plants.
The results nicely confirmed what Jaap van Dorsser has long stated about the comparative root performance of container and open-ground plants. The root system extended considerably farther from the open-ground plant, than from either of those container-raised.
The project demonstrates that open-ground seedlings are comparative with potted or planting bag in regard to establishment performance, and are potentially considerably cheaper to produce and to plant. It also demonstrates the vulnerability, to browsing and smothering, of Hillson-sized root trainer–raised plants.
But while the trial has firmly established the relevance of the open-ground method in establishing indigenous species, it barely scratches the surface of open-ground aspects begging to be researched, developed and trialled.
Direct sowing
Radiata pine is readily grown from seed sown directly in open-ground nursery beds. This is because the seed used has of high viability and emerging seedlings cope well in the open.
Direct sowing is significantly more economic than raising seedlings indoors, in plug trays.
Developing techniques for similarly direct sowing key indigenous species, with the necessary attributes, is a priority.
Harakeke probably has an unassailable lead over other species because of these attributes:
- • Valuable establishment species, including as a transitional filler
- • Clumping is acceptable, allowing the multiple seeds to be sown
- • Most-readily established indigenous species open-ground.
This last attribute is due to harakeke’s rhizomatous root system, which is relatively immune to desiccation during the transplantation stage.
Two-year seedlings
It is probable that by planting larger seedlings, establishment costs can be reduced.
A significant percentage of restoration planting fails within the first two years, typically by being overwhelmed by competing vegetation. It is possible that establishment regimes can be devised that require no maintenance, and that these will be competitive, even discounting the percentage that fail completely, with regimes entail a significant maintenance component.
The particular advantage that open-ground has over container-based methods is in respect to producing larger plants. Unlike container-raised seedlings, which require re-potting, a second year in the nursery adds only incrementally to the cost of producing open-ground seedlings.
To test this strategy, the establishment performance of two-year and one-year open-ground seedlings need to be compared.
Harakeke is the obvious candidate species, but other species could be included in the trial.
Density
Only a small number of trials have been conducted, or are underway, that evaluate the comparative performance of different establishment densities, and ultimately a wide range of trials need to be performed.
However, because of the suitability of harakeke to the open-ground method, establishment trials comparing various densities of harakeke is a priority.
Filler ratios
It seems highly likely that harakeke seedlings can be economically produced and established in high volumes. The higher the ratio of harakeke, then, the greater contribution it will make to reducing the average cost of establishing a plant. Assuming a 15:1 ratio, filler and succession seedlings costing 30cents and $1.50 respectively, the average cost is reduced to 37.5 cents per seedling.
High percentages of harakeke, say 24:1 through to 1:1, need to be trialled to determine if there is a tendency for a monoculture of harakeke to develop.
Hybrid open-ground
A simple, six-month proof of concept trial of the e
NZopen™ container would determine if the configuration promotes the development of the necessary fibrous root mass. If it passed this first test, the concept could quickly and inexpensively be trialled to determine its potential role in low cost, low loss establishment regimes.
Strategic and focussed
British economist
Nicholas Stern warns that global temperatures could rise by 5° by the end of the century, and render much of the world uninhabitable. Regardless of just how much the world heats up, there is an unquestionable and urgent need for reforestation on an unprecedented scale. But only by adopting and adapting forestry methods, can indigenous species form a significant component of the response in Aotearoa.
While there are many potential areas relating to the open-ground method that
could be scientifically trialled, a strategic and focussed programme is imperative:
- • Direct sowing of open-ground nursery beds
- • Comparative cost and performance of establishing one-year-old and two-year-old seedlings
- • Comparative cost and performance of establishing different densities of seedlings
- • Comparative performance of different ratios of filler species
- • Preliminary proof of concept trial of eNZopen™ system.
Meanwhile, trials similar to those in the Mahurangi have been established in the Lake Taupö catchment, in 2009, with more to be established this year and in 2011.
Next section Conclusion: The Bottom Line
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Contents
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Part of a hope-based network restoring and enjoying the Mahurangi
Editor Cimino Cole
Mahurangi Regatta Saturday 28 January 2012
Mahurangi Coastal Trail Supporters walk
The Mahurangi Action Plan –inspired Open-Ground and
Telling the Scientists to Tell Us: While Copenhagen quibbles over a 1.5° or 2° target, British economist Baron Stern of Brentford, urges scientists to describe to the world just how unbearable warming of 4° or 5°, which is probably where temperatures are headed, would be. Photograph Scanpix/EPA/DPA