If you haven't already, you may wish to read
part 1 in this series.
Timberlands supports research into the wildlife in its native
forests.
Problems in New Zealand's native forests
"We are now going through what appears to be another wave of mass
extinctions which will not stop irrespective of total forest
protection and
preservation, and will not reverse without major research and
management
intervention." - an extract from an address by C. R. Richards, General
Manager Planning of Timberlands West Coast Ltd (TWC) to the 25th
Anniversary Workshop, New Zealand school of Forestry, Christchurch, in
November 1995.
He went on to list the threats to some of our native birds, the impact
of
wasps, the 30.000 tonnes of leaves, seedlings and flowers which are
consumed by possums each night.
My article in NZine describing the efforts of the staff of Nelson
Lakes
National Park and residents of St Arnaud, the adjacent township to
combat
these problems indicated how seriously the problems with wasps,
rodents and
possums were viewed in that area
(read the article).
Concern about forestry's impact on the forest's ecology
Rob Dalley described the indigenous forestry industry as particularly
"information hungry" and demanding extensive and intensive research
into
all aspects of the forest. Programmes are being set up to study the
ecology
of the forest and the impact of management.
Surveys of bird and bat populations
Rhys Buckingham, bird surveyor and consultant bird ecologist, from
Nelson,
wrote about the TWC surveys in "Green Monitor Issue 12", in October
1997, a
TWC publication. He reported that surveys of birds and bats have
shown
that there is a need for direct management of the endangered wildlife.
There appears to be a decline in numbers of great spotted kiwi, blue
duck,
kaka, rifleman, brown creeper and long tailed bat in the Grey and
Maruia
valleys, although there was minimal harvesting in these areas.
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The South Island Robin
Photo source TWC
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In the Eastern Paparoa Range thirty one native bird species were found
and
in the Maruia Valley twenty nine. Bellbird, yellow-breasted tit,
fantail,
grey warbler and silvereye were common in all the forests and weka and
robins were found in some areas.
In particular searches have been made for the kiwi, blue duck, yellow
head
and the South Island kokako. Methods of searching included playing
tapes of
birdcalls, searching significant habitats at certain times of the day
and
season, and walking through areas at night when the kiwi, other
nocturnal
birds and bats are active. A small electronic device that could
detect
ultrasonic bat calls was used at night.
The South Island kokako has been thought to be extinct for many years,
but
some signs in TWC forests could have indicated the presence of this
rare
bird - kokako-like calls, unusual moss grubbing, a feather which
possibly
came from a kokako and two possible sightings. The area where these
signs
were noted has been reserved.
Work as a bird surveyor is taxing, involving long hours walking
through
difficult undergrowth, often in heavy West Coast rain, and in some
seasons
surrounded by wasps.
12% of TWC beech estate now reserved
The areas found to be significant for bird life have been taken out of
production. 12% of the Timberlands beech estate has been set aside as
reserves, including riparian areas, and areas important for wildlife,
landscape, and recreational values. Some species which are
particularly
important to birds, such as kahikatea and rata, are excluded from
harvesting. In the valley systems the podocarp forest is important
for
wildlife.
Some large trees left for ecological reasons
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Slaty Creek - Mature red beech tree (>110cm DBH) retained for biodiversity and habitat reasons
Photo source TWC
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Large old trees are of particular importance to a number of threatened
fauna such as kaka and native bats. The trees are rich in epiphytes,
have
nesting holes and often well developed rots rich in grubs and
invertebrates. For each species, all trees over a prescribed maximum
diameter are retained e.g. red beech max 110cm, silver beech max 90cm.
Management allows for some trees to grow continually through into the
larger diameter sizes, thereby ensuring the presence of larger/older
trees
in perpetuity.
In forest modified by past logging, many forest margin birds are often
present year round, while in-forest birds such as kaka and parakeet
often
display a seasonal use. Kiwi are also frequent users of cutover
forest,
often being more abundant there than in adjacent un-logged forest.
Reasons for making land into reserves
Land is allocated reserve status for many reasons including the
protection
of landscapes, fauna, plant communities, historic sites or wahi tapu,
research areas, sites of particular tourism or recreational interest,
and
provision of buffer zones along streams and boundaries.
Designating riparian areas as reserves
Leaving areas of virgin forest along banks of streams prevents
unwanted
material entering the stream, and maintains necessary levels of shade.
Removal of shade leads to increased in-stream temperatures which can
be
harmful to native fish and other aquatic life.
Research into insect numbers in the beech forests
Timberlands funded research at Lincoln University investigating
insect
numbers and diversity in the West Coast beech forests. The study was
centred on four adjacent harvested and unharvested areas in the Buller
district felled in 1953, 1955, 1986 and 1995. The result of these
studies
showed no consistency in the abundance and diversity of insects in the
unharvested sites and no evidence of severe effects on insects in the
harvested sites.
Impact of gaps in forests
A Ph.D. thesis investigating the effects of management on litter
decomposition rates and invertebrate diversity and abundance, has
shown no
significant difference between natural gaps, gaps created during
harvesting, and forest with no gaps.
Controlling the predators
The main predators which are depleting the bird population in native
forest
are possums, stoats, rats and mice. A method of controlling these
by
secondary poisoning has been tried as stoats, particularly pregnant
females
in spring, are shy of eating bait.
How was the bait offered?
Stoats were trapped and transmitters fitted prior to poisoning. Slow
acting
rat bait was used. This killed the rats and mice which in turn were
eaten
by stoats.
After poisoning the stoats' bodies were recovered and the cause of
death
confirmed by analysis of the liver. All stoats that had been radio
collared died, indicating a 100% success with the poisoning method.
The method has since been utilised in subsequent trials in different
forest
types, at times of different rat and mouse abundance, and with
different
poisons - all with equal success.
Variation in the seasons can make the birds' enemies more
active.
Normally the forest would have been humming with wasps, but when we
visited
it was after an unusually wet season which had greatly reduced their
numbers.
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South Island kaka
Photo source TWC
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When there is a particularly heavy seeding of the beech trees, rodent
numbers explode. Stoat numbers also increase with this abundance of
their
natural prey in the classic "predator - prey" response. At the end of
the
summer season however, rodent numbers decline rapidly, drying up the
stoat
food supply. At this point stoats are forced to target other sources
of
food, primarily birds, for their survival. They attack the birds that
nest
in holes, so a heavy seeding puts birds such as the kaka, parakeet and
yellowhead more at risk.
Continued research
Research is now focused on finding the ways to administer poison to
the
predators with the least possible risk to the native wild life -
finding
what is the minimum effective dose and what type of bait stations or
pellets are least likely to harm birds.
Comment by ecologist, Henrich Moller
In the Christchurch Press in Saturday Soap Box on September 19, 1998,
Dr
Henrich Moller wrote:
"Private investment in research and active ecological restoration
offer
tremendous gain for conservation and welcome relief to DOC, who we
expect
to work ecological miracles on a shoestring budget."
It is to be hoped that Timberlands West Coast will continue to fund
such
research.
Read the
response from a conservationist...
