Timberlands And Sustainable Management Of Native Forests – Part 3

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.

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

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.

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…