Management Guidelines for Remnant Vegetation
being Harvested for Cutflowers
Keywords:
management, reseeder, resprouter, disease, harvesting
Location: Southwest
WA
Land for Wildlife
Liesl Rohl and Russell Smith
Author:
.
Harvesting wax flower. Photo: D. Lamont
Western Australia's cut wildflower industry has
become a multi-million dollar industry. Currently in
WA over 250 species of protected flora are
harvested for their flowers and foliage and more than
600 pecies for their seed from both Crown land and
private property.
Flower production from bushland on private property
is increasing as land holders become aware of the value
of their flora. It is now estimated that more than 20% of
WA's native cutflower exports come from remnant
vegetation on private property. Management of these
bushlands is required to ensure that the bush is preserved,
not only because of its conservation value, but also to
ensure sustainable harvesting can continue into the
future.
Sustainable harvesting practices are also required
under Commonwealth law where the flora is harvested
for export. Western Australia has a management program
for the harvesting of native flora which provides for flora
exports, and these management guidelines are a strategy
to support this management plan.
It should be understood that some techniques which
are used to improve production of protected flora for cut
flowers and foliage from remnant vegetation may have
the potential to adversely affect the nature conservation
values of that vegetation, and to contribute to
soil and water degradation. Land managers are
thus advised to carefully assess management practices
and their potential impacts before undertaking bush
management for flower production.
Seasonal variations also need to be taken into account.
For example, in drought years plants become stressed. If
you harvest as you would in a `normal' year this
may stress the plants further and they may die.
The following guidelines have been written as a
general guide for managing remnant vegetation for cut
flowers.
FIRE
Fire affects plant regeneration in different ways
depending on whether the plant is a reseeder or a
resprouter.
Reseeder species rely upon seed stored on the plant
or in the soil to replace parent plants after fire. To
replenish this `seed bank', plants must be able to reach
maturity, flower and set seed. The time involved varies
for different species and it is best estimated by studying
the plants you wish to harvest as well as the other species
in your remnant(s).
Some species only regenerate from seed, these
species are called obligate seeders. It is important
that fires do not occur at a frequency which prevents
these plants establishing a new store of seed. For
remnants which are harvested for cut flowers and seed,
the time between managed fires should be increased
to allow a greater time for a seed store to be built up.
Resprouters shoot again from buds protected
beneath their bark or on their rootstocks (underground
stems). To do this they use up food reserves stored in
roots and stems.
These plant species can generally survive stress such
as fire, drought and some grazing. However, if fire or
grazing occurs too frequently these plants do not have
enough time to build up new food reserves and each
resprouting becomes weaker until the plant eventually
dies. If resprouter species are killed, viable seed needs
to be available to re-establish them.
Many plants reproduce by both methods, seeds
and resprouting. Each remnant will have a mixture
of reseeder and resprouter species.
The required interval between fire may vary between
remnants, depending on the species present. Fire may
increase the number of native species in an area if it has
not been burnt for a long time, provided appropriate seed
is present, and the fire is at the right temperature and time
of year.
However, if the fires are too frequent, especially in
small remnants which have been harvested for flowering
stems, local extinction of fire-sensitive native species
may occur and weed establishment will increase,
especially if there is potential for weeds to enter
from surrounding farmland.
Weeds produce many thousands of seeds each year
and are not disadvantaged by frequent burning. Many
native plant species are weakened by fire and are
replaced by weeds. Burning should not be used as a way
of removing weeds.
The desirable time to burn for both reseeders and
resprouters is in autumn after the first rains. This
ensures that there is enough water to help with seedling
establishment and helps prevent shallow rootstocks from
being harmed.
If burning is used as a management tool, the time
between fires should be at least twice as long as the time
to maturity of the slowest growing reseeder species. It
is advisable to separate the remnant bushland into a
number of areas using firebreaks so that only part of the
stand is removed from flower production at any one time.
Another benefit of dividing your remnant into
compartments is if a burn is followed by a drought year,
a plague of locusts or rabbits, or sheep get into it, not all
of the remnant is at risk of being degraded - only the part
that has been burnt.
DISEASE
Care should be taken not to introduce Phytophthora
root-rot and other diseases into the remnant bushland.
Although some species are resistant to Phytophthora
fungus other species occurring in the remnant may be
vulnerable. Many species in the Banksia, Isopogon,
Lambertia, Persoonia, Petrophile, Xylomelum,
Thryptomene, Verticordia, Andersonia, Astroloma,
Lysinema and Hibbertia genera are particularly sensitive
to Phytophthora.
The Phytophthora pathogen is most often spread in
soil attached to vehicles and on the bottom of shoes,
particularly in moist environments. Great care must be
taken to prevent its introduction or spread. Harvesting of
flora in warm wet conditions is likely to spread this and
other diseases which are active in moist conditions.
Good hygiene measures are essential, e.g. clean all
machinery, vehicles and footwear between each stand
and restrict access by livestock and vehicles (see
references for detail).
Aerial canker fungi are also a potential problem,
especially for some Banksia and Eucalyptus species.
Secateurs should be disinfected between plants to prevent
cross-infection and pruning paint can be used to protect
fresh cuts. Dead or dying stems should be cut from the
plant below the site of disease expression (figure 1),
removed and burnt to prevent disease spread.
Secateurs and knives should always be disinfected
between stands to reduce the risk of disease introduction.
Wiping the secateurs and knives with a cloth soaked in
methylated spirits is a quick way of disinfecting them.
Land for Wildlife
PRUNING
Some species, including many banksia and dryandra
species, respond well to pruning. Pruning of plantation-
grown and wild banksias and dryandras is considered a
good horticultural practice which is used to improve the
production of commercial quality blooms. In general it
takes approximately 1 to 2 years after pruning for bloom
production to increase for these species.
Pruning can be used as an alternative to burning, with
bloom production being much quicker than after a burn.
Light pruning (into 1-2 year-old wood) increases the
proportion of commercial quality blooms, but heavy
pruning, into 4 - 6 year-old wood, often decreases bloom
production and may even kill some of the plants. In
general, pruning should not remove all the green leaves
from the stem being cut.
The age of stems can be gauged for banksias and
dryandras by counting the number of annual nodes
(raised areas on stem formed at the end of each growth
season) back from the growing tip (figure 2).
Tip pruning can also be used at an early stage to
increase branching and hence the number of stems.
FENCING
Stock and rabbits eat the seedlings, compact the soil,
cause soil erosion, and can also spread plant diseases and
introduce weeds into the area.
It is strongly recommended that bushland used for
cut-flower production be fenced to exclude stock. Studies
have shown that the general health of remnant bushland
declines if it is grazed.
Figure 2. How to age banksias
FERTILISER
Fertilisers are generally detrimental to remnant
bushland. Some species, particularly members of the
Proteaceae (eg Banksia, Dryandra), are harmed and
weed invasion is encouraged. If applied near waterways,
fertilisers also have the potential to be washed into them,
and contribute to the pollution of waterbodies in the area.
Fertiliser addition is not recommended in most
situations.
SLASHING
Slashing is not recommended for reseeder species.
Slashing alters the bush vegetation if a large proportion
of non-sprouting reseeder plants are killed by the slashing.
If slashing is to be conducted to promote growth of
resprouters the following guidelines should be followed:
•
slashing should be done 30 cm above the ground
•
only a portion of the remnant bushland is slashed at
any one time to ensure adequate seed
germination and seedling survival in the area
•
slashing be conducted from mid autumn to early
winter
•
tractor tyres may cause some compaction of the soil
and damage to other species. Tractor powered
slashing should not be carried out more frequently
than once in 10 years. To reduce the risk of soil
erosion, tractor-powered slashing should not be carried
out on steep (> 20%) slopes.
Figure 1. Aerial canker.
HARVESTING
Plants without rootstocks (underground stem), have
a limited capacity to resprout, and incorrect harvesting of
young plants can result in plant death. Heavy harvesting
of reseeder species reduces the general health of plants
and their capacity to produce and accumulate seed. It is
therefore important to ensure that there will be sufficient
seed reserves to replace the parent plants in the event of
a fire.
Seed is also lost through predation by rabbits, birds
and many insects; this needs to be taken in to account
when harvesting flowering stems from reseeder species
such as Banksia baxteri, B. coccinea, B. hookeriana,
Dryandra formosa, and Verticordia eriocephala.
Harvesting all the available flowers from a bush, or
when the plant is too young, often kills the plant especially
if no shoots with green leaves are left below the harvest
cuts.
In general the following should be followed for
reseeders:
•
no more than 30% of blooms should be harvested
•
a stand should not be harvested for flowers or foliage
for a year prior to it being burnt
•
green leaves must be left below the harvest cut
•
knives or secateurs should be used for harvesting
to help get an even cut.
Plants which resprout often die if harvested at ground
level, others regenerate very slowly. These species also
suffer from stress if harvested too young.
In general the following harvesting techniques should
be followed for resprouters:
•
plants should not be cut less than 30 cm above ground
level
•
a knife or secateurs should be used for harvesting
to help get an even cut
•
depending on the number of good quality stems and
the age of the plant, about 20% - 60% of the current
season's growth can be taken.
LICENSING
Under the Wildlife Conservation Act 1950, flora
native to Western Australia is protected. If you wish to
sell protected native flora taken from private
land you need a Commercial Producer's
License or a Nurseryman's License (PN). This
license costs $25 per year.
Contact your nearest CALM office or CALM in
Como for an application form.
Note: the landowner's permission is also required
to harvest protected flora from private property.
Published by the Department of Conservation and Land Management, Perth.
All correspondence should be addressed to: The Editor' Wildlife Notes', CALM Wildlife Branch,
Locked Bag 104, Bentley Delivery Centre, WA 6983. Phone: (08) 9334 0530, Fax (08) 9334 0278
Design and Desktop publishing by Louise C. Burch Graphic Designer.
Meeboldina scariosa (formerly Leptocarpus
scariosus) being harvested. Photo: C. Robinson.
FURTHER INFORMATION
Specific management guidelines and recommendations
have been written for the following species:
Agonis sp., ("coarse ti-tree"), Agonis parviceps,
("fine ti-tree"), Banksia baxteri, ("baxteri"), B.
coccinea, ("coccinea"), B. hookeriana, ("hookerana"),
Dryandra formosa, ("formosa"), Meeboldina scariosa
("velvet rush" for female plant, "seeded rush" for
male) and Verticordia eriocephala ("cauliflower" or
"brownii").
These guidelines can be obtained by contacting CALM
Wildlife Branch on 9334 0455.
REFERENCES
Hussey, B.M.J. and Wallace, K.J. 1993.
M a n a g i n g Your Bushland.
Department of
Conservation and Land Management, Perth.
Kilgour, S. 1999. Managing Dieback in Bushland:
a guide for landholders and community conservation
groups. Dieback Working Group, Kalamunda.
About the Authors
Liesl Rohl is the Flora Industry Botanist at CALM
Wildlife Branch, Como.
Russell Smith is Ecologist (Rare Flora) based at
CALM, Bunbury.
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