An
observation by Rex Bushell
Native flora restoration in cities is under
constant pressure from hybrids, selections of genetic variations and selective
breeding done by commercial nurseries targeting new and varied cultivars of
native origin for the domestic urban market. These commercial variances will
cross with many genetically pure species that may be planted by restoration
groups or cross with old established canopy trees that have existed in the city
for many years. Some species like flax, manuka, lancewood, kowhai and totara
are particularly vulnerable.
Over time, depending on the life cycle of a
particular flora species, this will create a genetic evolution within the
native forest reserves in or close to, a city.
Is this good or bad? Either way it is inevitable.
It can be slowed down by planting eco sourced plants but it cannot be stopped.
For the flora purist this may not be something to look forward to.
To look at it from the native fauna angle,
they will happily eat the berries or drink the nectar of a modified native. In
fact, their participation is often the cause of genetic variation by
transferring the pollen from a domestic selection to a native.
Because of the large variation of flora
species within a city there is an opportunity to target non native plants that attract
- as opposed to just feeding – a targeted fauna species such as the tui and bellbird. This is why Banksia integriflora is being promoted. There is plenty of
opportunity to plant Banksia integriflora
in parks around a city where exotic trees are planted and in domestic gardens
without compromising the integrity of native restoration projects. The gardens of the University of Waikato would
be an excellent example where natives and exotics are planted along side one
another including Banksia integriflora resulting in a high population of tui.
Banksia
integriflora may have a propensity to be invasive
in some parts of New Zealand but this is not the case in the Waikato. Bunny and
John Mortimer had a tree growing at their Taitua Arboretum and only ever got
one seedling. Maxine Frazer has a QE11 block at Te Pahu and has a Banksia integriflora growing by her house and has never seen a seedling. On the road verge by 90 Wellington Street in
Hamilton there is a very fine specimen that must be all of 100 years old with
no proliferation of seedlings in the area.
To
summarise, in city environments exotic flora tends to dominate over
natives. Because of this management
plans have to be more adaptable if our target is to reintroduce or sustain
native fauna species within our cities.
