Oral Submission Presentation by Blake Foster - New Zealand ...

Above (2008) and below (2010) - outlier wildings in the upper Twizel river catchment. Their uniform age indicates
that they arrived at the same time in the early 1990s, and that such a distant spread event does not happen often.
Unfortunately, they were allowed to cone before removal, resulting in islands of fringe spread (obvious in bottom photo).
All fringe spread has been to the south of parent trees, indicating the prevailing north wind (right to left in photos). If
removed before coning, it should not be onerous to keep this site free of wildings – as invasion is infrequent.
Left – Twizel river flats (2010). An ‘island’ of
young wildings, parented by a lone outlier wilding
parent tree, which was felled a few years
previously (being held up in photo). If this tree had
been felled before age 5, no wildings would be
present. Its progeny are now aged 5-6 and just
starting to cone. If left intact and allowed to
disseminate seed, wilding removal costs will be
increased significantly. Hence the wilding control
motto of “Stitch in time saves nine”
Left (2009). Looking
south from Little
Rhoboro Hills ridge.
Contorta pine is rapidly
becoming dominant,
except in middle distant
left where improved
pasture is preventing
invasion. Containment
(and possibly forest
management) is the
cheapest option for this
area, where seed sources
may remain upwind.
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