Australasian Plant Conservation
Originally published in Australasian Plant Conservation 18(3) December 2009 - February 2010, p 15-16
Aerial mapping of two riparian vine weeds in
Tweed Shire, New South Wales
Sally Jacka1, Carla McKevitt2 and Tom Alletson1
Shire Council, Murwillumbah. Email: firstname.lastname@example.org
Proprietary Limited, West Burleigh, Qld.
Madeira Vine (Anredera cordifolia) smothering a Casuarina cunninghamiana tree. Photo: Ecosure
Tweed Shire covers an area of 1303 km2 encompassing the whole of the Tweed River Catchment. The catchment, consisting
of three main waterways—the Oxley River, the Tweed River and the Rous River—is
surrounded by the Mt Warning (Wollumbin) caldera, which is part of the World
Heritage listed Gondwanan Rainforest. The Shire consists of various vegetation
communities, including the Environment Protection and
Biodiversity Conservation Act (EPBC Act) listed Littoral Rainforests and
Coastal Vine Thickets of Eastern Australia Threatened Ecological Community. The
Shire is home to 43 flora and 25 terrestrial fauna species listed under the
Rainforests and Coastal Vine Thickets have
been fragmented due to past sand-mining, urban expansion and clearing for
agriculture. The riparian network provides important corridors for genetic
exchange and movement of fauna, connecting component populations of rainforest
and World Heritage areas.
The spread of introduced vine weeds in New South Wales is recognised as a key threat to the preservation of native flora and
fauna. Cats Claw Creeper (Macfadyena unguis-cati) and
Madeira Vine (Anredera cordifolia) are regarded as
the most severe weed threat to the environmental quality of waterways and
riparian habitat in the Tweed River Catchment and are a serious threat to the
biological diversity of the Shire. Their proliferation there is severely
degrading some of the highest conservation value forest by smothering canopy
and understorey and killing
Cats Claw Creeper and Madeira Vine are
native to South America and were introduced to Australia as ornamental plants.
Cats Claw Creeper is a tuberous, woody climber with tendrils ending in sharp,
hooked claws. Madeira Vine is a semi-succulent perennial that successfully
reproduces from both aerial and underground tubers and will regrow from
axillary buds still attached to leaf petioles (Big Scrub Rainforest Landcare
Group, 2008). Both species are characterised by prolific flowering, rapid
growth and effective dispersal within the riparian environment. They infest the
canopy of native vegetation and can rapidly smother and kill mature trees,
ultimately toppling them and creating gaps in the riparian corridor which leads
to additional weed infestation. As a consequence, riparian zones become
dominated by non-native species.
In July 2008, the Tweed Shire Council, with
New South Wales Environmental Trust funding, contracted Ecosure Pty Ltd to
survey and map the extent of riparian vine weeds in approximately 730 km2 of the Tweed River catchment (see Ecosure, 2009).
The aims of this project were to identify
and map the extent of Cats Claw Creeper and Madeira Vine infestations within
the Oxley, Tweed and Rous rivers catchments. The primary purpose of mapping was
to provide a framework to guide the preparation of a strategic plan for vine
weed suppression at a strategic scale. It has enabled the identification and
assessment of existing vine weed locations and set priorities for actions and
resource allocation to effectively suppress these weeds.
Both Cats Claw
Creeper and Madeira Vine are often interspersed within the canopy of native
species and generally are difficult to discriminate from other vine species
without close inspection. However, both species present distinguishing colour
displays when flowering, and their in situ distribution
can be estimated by mapping the extent of the flowers. Flowering periods vary
between three and six weeks, but flowering may be asynchronous. Variations in
flowering times are caused by elevation, aspect of habitat towards the sun,
water and nutrient availability of each population of vine species. Flower
retention may also vary with ambient conditions.
from a helicopter were made when the vines were flowering and highly visible
within the canopy of riparian vegetation. Most areas were surveyed at least
twice during the flowering period to account for flowering variability. This
method of mapping is the most effective means of covering large distances and
negates the problems of passing through hard terrain, dense vegetation on the
ground and gaining land owner permission to access private land. Helicopters
also allow for a high level of speed and manoeuvrability that are ideal for
surveying the terrain within the Shire.
Flowers of the Cats Claw Creeper (Macfadyena unguis-cati) (top) and Madeira Vine (Anredera cordifolia) (bottom).
Photos: Eddy Roberts (top) and Ecosure Pty Ltd (bottom).
Eight hours of
ground surveys were performed for each target weed species, to ensure that the
species mapped from the air as Cats Claw Creeper and Madeira Vine were correctly
identified. Randomly located sites were also surveyed to confirm that there
were no target weeds in areas that were mapped as ‘no weed species being
An ike 305 laser
GPS (Global Positioning System) was used with an integrated 3.2 mega pixel camera,
a 905 nm (invisible infrared) laser range finder (1000 m), a digital compass
and an inclinometer (Survey Lab in New Zealand). This unit can capture
positions remotely with offset positions calculated in real time. The unit was
coupled with a Sokkia AXIS3 Differential unit that receives real time
correction through the OmniSTAR Virtual Base Station system that allows for
software used was an ike GPS version of GBM Mobile (MapInfo). It was customised
as necessary to suit the project, allowing specific attributes of each weed to
be captured in the field as meta data.
The patch size and relative density of each
weed infestation was assessed and attributed to the location at the point of
data capture. This delineation allowed the production of the maps, which
illustrate the position, density and size of each weed patch. Different symbols
were used to represent the size and density of weed patches within the
aerial surveys, 521 ha and 172 isolated infestations of the target weeds were
identified and mapped. Generally, both weeds occur on or near waterways with
only a few patches found terrestrially as ornamental specimens in gardens.
Both of the target weeds are distributed
throughout the three main waterways surveyed (the Oxley, Tweed and Rous
rivers). The only waterways where the target weeds were not identified were
tributaries to the Rous River. All other tributaries contain some level of
infestation of the target weeds, although some only at the very downstream
section where they join the main waterways.
Eight small patches of Madeira Vine and four
small patches of Cats Claw Creeper were identified on the ground that were not
seen from the air. These sites were not mature infestations, with the majority
of the weed mass not having reached the canopy. This is a known limitation of
aerial surveys where vines growing beneath the canopy may be shielded from
The knowledge of the mature infestation
locations gained through this survey will be an extremely useful tool that will
aid the planning and management of future weed control programs. Key target
properties will be identified for vine weed control with priority given to
upper-most stream infestations of streams not heavily infested. Using this
strategy, it may be possible to eradicate the vine weeds from small
sub-catchments. When planning the strategic treatment of these weeds,
consideration will also be given to the protection of areas of high
Ecosure (2009). Aerial mapping of riparian weeds. Report to Tweed Shire Council, Ecosure, West
Big Scrub Rainforest Landcare Group (2008). Common weeds of subtropical rainforests of eastern Australia.
Big Scrub Rainforest Landcare Group, Bangalow, NSW.