Result of Trial Intervention on Phoenix palm seedling
Phoenix palm seedling #1 is - or rather was - in ZoneCaKSS#1
It was first observed in June 2018, in the midst of a beautiful dense mass of parataniwha
too large to be uprooted.
During further informal survey in August 2018 it was suppressed by looping and knotting, , an ad hoc 10 second intervention during informal survey. This intervention required no tools or skill other than the identification of the palm as exotic, therefore invasive.
This week it was found rotted at the base
which separated unexpectedly on examination of the lower plant. The bottom end of the stem was found to be completely soft and brown.
Inspection of the ground beneath revealed no live material, but the site of the root will be monitored.
Rationale
Our first ad hoc interventions of this type were aimed at slowing the growth of woody tree/shrub weeds to delay their suppression of adjacent native vegetation. Similar interventions on Elaeagnus having been found to result in long-term suppression and, after a year or so, easy uprooting of at least some specimens (not all were monitored ongoing), presumably due to fine root rotting.
We tried the technique on this exotic palm seedling, which was growing vigorously and endangering the survival of adjacent nikau juveniles and seedlings. We hoped the interim suppression would, at some time in the future when priorities permitted, enable the Ecocontract's annual weed control operation to control it before it became too costly to address.
In this case at least, the results exceeded our expectation.
Background
We had recently identified a Phoenix palm seedling of similar size ie about 40cmH, at our other Trial Site, Gahnia Grove, and looped and knotted its leaves to suppress its growth until we decided how to deal with it.
By late July 2018 that Gahnia Grove specimen hadn't grown further, so we continued to observe it without further intervention.
Growth of an escaped or new leaf was observed some months later, and this leaf was threaded into the loop. At time of writing (September 2019) there has been no further growth in that specimen.
In the interim, thanks to support from Auckland Council's Regional Environment and Natural Heritage Fund, we were able to monitor the same intervention on a number of Phoenix palm seedlings in our Kaipatiki Creek methodology trial, in which Phoenix palm seedling #1 was an ideal, easily accessed first candidate for monitoring.
Other possible causes of the death of Kaipatiki Creek Phoenix seedling #1
Weed control by Ecocontract has taken place in parts of the Reserve recently, but this specimen was (and remains) cordoned within the Trial area, marked with orange tape, and communicated to the acting Operations Team Manager prior to their operations. The operations team were advised of the Trial area, and it is unlikely that a mistake occurred, but it is impossible to be absolutely certain that no
herbicide was involved in this plant death.
There is also the possibility that this plant was affected by sewage overflow or chemical decomtamination of this area, which occurred in May 2019. Sewage overflows and decontamination are, however, a regular event, according to Reserve users.
Nonetheless, we look forward to the result of the same technique being monitored on other specimens in the Kaipatiki Creek methodology Trial, including some larger, ie to c.80cmH. We are also monitoring the suppression by partial leaf-stem breakage on two Chusan to c. 1.5mH, in the estuarine area. They are unmarked, but at time of last observation in about June 2019, they showed no sign of intervention other than our own.
Here are all recorded observations of this specimen, from first survey to its demise.
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