Miscommunication
can have entirely happy consequences.
As
mentioned earlier, one of the strands in the exploration that led to the open-ground and container-raised indigenous plants comparison was the proposition that
toetoe planted 50:50 as a filler species would reduce the time and cost of achieving canopy closure.
Indigenous species restoration advisor Chris Ferkins, principal advocate of toetoe as a filler species, considers toetoe to be the optimal indigenous species both to achieve canopy closure, and to restore the damp, shade conditions enjoyed by indigenous ground-dwelling fauna.
Three factors are responsible for the high cost of establishing indigenous species, as compared with exotics:
- 1 The cost of plants
- 2 The cost of planting
- 3 The cost of maintenance.
Depending on plant size and spacing, up to eight years of maintenance can be necessary to protect plants from competition by weeds—kikuyu the killer in the north, blackberry the bête noire of restoration planting the south.
An obvious strategy would be to combine toetoe produced open-ground cheaply and in high volumes as filler plants to drive down the average cost of plants and at the maintenance costs by much reducing the time to canopy closure.
If it worked, a pivotal breakthrough in establishing indigenous species will have been achieved.
In spite of the potential of open-ground toetoe-as-a-filler, it was reluctantly decided that adding that element to the open-ground and container-raised comparison would result in a trial with far too many variables.
The first priority had to be testing whether open-ground methods were indeed competitive with container methods that predominate.
Then, far too late in the year than planting should generally be contemplated, it was realised that, as a result of an earlier miscommunication, the project was obliged to take delivery a considerable surplus of plants raised for the trial, in PB3-sized containers. When it was then learned that a large proportion of the plants were toetoe, it was decided to make a virtue of the situation by establishing a 50:50 toetoe trial.
Because the trial would not also compare open-ground and root trainers, it only needed to be a third of the size initially contemplated.
At luck would have it, an esplanade reserve at Hepburn Creek, Mahurangi had recently been re-fenced. The contour and soil type was reasonably consistent, and a neighbouring property holder was motivated to help establish and care for the planting. Critically, given the lateness of the season, the neighbour was also able to supply water to the site.
Then, the morning planting was to begin, it was realised that another opportunity was available. The high proportion of harakeke meant that the trial could be a three-way comparison:
- • 50:50 toetoe and four other revegetation species
- • 50:50 harakeke and four other revegetation species
- • Six revegetation species including toetoe and harakeke.
There were several reasons for also trialling harakeke as a filler species. The main one was that harakeke, over many decades raised open-ground, had proved to be the singular species that was ‘bomb proof’ at the establishment stage. This is attributed to the fleshy root system of harakeke, which is not subject to the desiccation rates that bedevil most plants when bare-rooted. If there was a delay in the planting, of if the soil was unseasonably dry, harakeke survived when other species raised open-ground perished.
It was the reason that harakeke was the only open-ground species that Taupö Native Plant Nursery left in its catalogue.
Further reasons to include harakeke was that the vigour the displayed early in the Sandspit Road and Silverdale trials, relative to the toetoe, and the likelihood that it can be readily grown from seed, open-ground. If the expensive seedling plug stage can be eliminated, harakeke could be produced, potentially, as cheap as (chipboard!) radiata pine seedlings.
Chris has found that making every other plant a toetoe, checkerboard-style, weeds are beaten in around nine months. Then, because toetoe is light-dependant, it eventually bows out in favour of the taller growing shrubs and trees planted.
It’s not pampas Toetoe, in the northern part of the North Island is generally unloved. But in fact it is all but non-existent, compared with the invasive South American pampas, which tragically is now endemic. The quick way to identify this exotic pest is by the profusion of curled leaves at the base. The indigenous species don’t have these carpenter’s plane shaving –like leaves. Nor do they have the carpenter’s plane –sharp edges.
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The Open-Ground and Container-Raised Indigenous Plants Comparison is a Sustainable Farming Fund project.
Hepburn First for Science: The efficacy of toetoe and harakeke as a filler species is scientifically trialled for the first time, on esplanade reserve land at Hepburn Creek. Photographer David Bergin
Too Soon to Say: Early indications are that while toetoe may prove to be a quicker filler than harakeke, it is initially much more vulnerable to smothering by competing grasses. Photographer Michael Bergin