Turner, P. J., Winkler, M. A., & Downey, P. O. (In Press). Establishing Conservation
Priorities for Lantana. The 14th Biennial NSW Weeds Conference Proceedings, 25-27
September 2007. University of Wollongong, Wollongong.
ESTABLISHING CONSERVATION PRIORITIES FOR LANTANA
Peter J. Turner, Marion A. Winkler and Paul O. Downey
Department of Environment & Climate Change (DECC)
Pest Management Unit, PO Box 1967 Hurstville NSW 1481
http://www.nationalparks.nsw.gov.au/npws.nsf/Content/Lantana_threat_to_biodiversity
ABSTRACT
Conservation priorities are best guided by the knowledge of what is threatened.
However, determining which species are threatened by weeds is difficult given
that: (i) few scientific studies exist on biodiversity impacts, (ii) many weeds
occupy large geographic areas, (iii) native species across a range of
environments could therefore be potentially threatened, and (iv) the diversity of
species at risk can be large (from invertebrates and vertebrates to plants). The
recent assessment of the impacts of bitou bush (Chrysanthemoides monilifera
subsp. rotundata) on biodiversity led to the development of the Weed Impact to
Native Species (WINS) assessment process. Using the WINS process, an
assessment of the impacts of lantana (Lantana camara) has been undertaken
and a list of native species at risk from lantana invasion across the core
infestations in NSW and Queensland has been compiled. Like the bitou bush
process this has lead to a significant increase in the understanding of biodiversity
impacts and the number of species thought to be at risk. Whilst a list of
threatened biodiversity gives a good starting point, it alone does not result in
conservation outcomes. Thus a second stage is needed in which on-ground
information of lantana’s distribution is matched with the specific native species at
risk and individual site conditions. This information is ranked to produce a list of
priority sites for control, independent of land tenure. This two-stage process is
essential for targeting control to areas where the benefits to biodiversity are the
greatest.
Key words. biodiversity, environmental weed, Lantana camara, monitoring,
native species, selecting sites for control.
INTRODUCTION
Most land managers acknowledge that weeds pose a threat to biodiversity, but
determining such impacts across the entire distribution of a weed is a difficult and
time consuming task (see Adair and Groves 1998 for a description of
techniques), especially given the limited resources available to manage
environmental weeds. Thus the need to determine impacts must be balanced
against the need to implement management practices on the ground (Grice et al.
2004) and the immediate need to protect biodiversity. Implementation of
management often occurs at the expense of gaining knowledge of impacts.
Compared to the number of studies which have assessed the effectiveness of
weed control techniques (Williams and West 2000), there are very few studies
that have measured the impact of environmental weeds on biodiversity (Adair
and Groves 1998; Grice et al. 2004). Yet, the knowledge of the impacts of weeds
on biodiversity is essential while undertaking control in order to restore native
plant and animal communities (Walker and Smith 1997; Gratton and Denno
2005), as control alone will not automatically result in their protection (Luken
1997; Downey 2007 - in press).
ASSESSING THE IMPACTS OF WEEDS ON BIODIVERSITY
The Weed Impact to Native Species (WINS) assessment process was developed
to determine the impacts of weeds on biodiversity in a short timeframe (see
Downey 2006). A major advantage of the WINS approach is that impacts, both
positive and negative, can be determined across a range of biodiversity which is
important given that the majority of previous studies that have only investigated
negative impacts to plants (Adair and Groves 1998). Some native animals utilise
weeds for food or shelter (Loyn and French 1991) and therefore must also be
considered when weed control is contemplated .
LANTANA (LANTANA CAMARA)
Lantana is a scrambling or thicket forming shrub from tropical America which has
spread along the east coast of Australia with the main infestations in NSW and
Queensland (Swarbrick et al. 1998). Lantana poses a major threat to biodiversity,
for example Coutts-Smith and Downey (2006) identified lantana as the most
commonly occurring weed threat, threatening ten percent of the 945 threatened
species in NSW. It invades many ecological communities (eg open forests and
woodlands) and can become a dominant understorey species in native
ecosystems (Day et al. 2003), preventing regeneration and succession,
particularly in rainforests (Kooyman 1996). In addition, lantana is thought to be
allelopathic (Gentle and Duggin 1997) which may also lead to the decline of
some native species.
Lantana is a Weed of National Significance (WONS - Thorp and Lynch 2000) as
well as a significant regional weed. For example, an assessment of 200 invasive
weeds in south-east Queensland ranked lantana as the worst weed based on its
invasiveness and ability to form monocultures (Batianoff and Butler 2002). The
invasion, establishment and spread of lantana has also been listed as a Key
Threatening Process under the NSW Threatened Species Conservation Act 1995
(NSW SC 2006). Despite these negative impacts, lantana has also been
recorded to have positive benefits for native species. For example, survival rates
in Australian brush-turkey (Alectura lathami) have improved with the availability of
lantana thickets (Goth and Vogel 2002) and black-breasted button-quails (Turnix
melanogaster) use lantana patches for feeding, roosting and nesting (Smith et al.
1998).
Lantana is now widespread and complete eradication is not feasible. Given that
control is also not possible across the entire range, control programmes which
are aimed at protecting biodiversity need to be directed to areas where control
will have the greatest benefits to biodiversity. This will ensure that the maximum
benefit is gained from limited resources as well as limiting non-target biodiversity
impacts. To achieve such conservation measures, information on the biodiversity
impacted both positively and negatively by lantana and specific site information
are required. Control techniques and recovery actions can then be tailored to the
species known to be impacted.
MINIMISING THE IMPACTS OF LANTANA TO BIODIVERSITY
The Department of Environment and Climate Change (NSW) in conjunction with
Biosecurity Queensland (DPI&F) are undertaking a national assessment of the
impacts of lantana biodiversity using the WINS assessment process (Turner et al.
in prep). The results will be used to develop a management strategy to reduce
the impacts of lantana on native biodiversity (DECC 2007), based on the model
developed for the NSW Threat Abatement Plan (TAP) for bitou bush (DEC 2006).
WINS assessment
The WINS assessment involves four steps: (i) literature review of impacts; (ii) a
series of targeted workshops involving people working with lantana or native
species throughout lantana’s range in Australia; (iii) the compilation of a draft list
of species at risk which is circulated and reviewed; and (iv) a final list of
biodiversity ranked to determine the species most vulnerable to lantana invasion
(see Downey 2006 for further details). Twenty WINS workshops have been held
across NSW and Queensland encompassing 199 participants. The majority of
participants were local government employees (23%) or State park staff from
Queensland (21%) and NSW (20%).
Determining species at risk
The interim list developed from these workshops and a review of literature,
include native plants, animals and ecological communities, as well as weeds that
co-exist or replace lantana following control and pest animals that utilise lantana
infestations. An initial analysis of the interim list of species at risk revealed 1,247
native plant species and 83 native animal species at risk (Turner et al. in prep).
Another 83 different native animal species were also reported to receive positive
benefits from the invasion of lantana, with a further 58 animal species reported to
have received both positive and negative impacts. The number of weed species
that co-exist or replace lantana following control was estimated at 144 (Turner et
al. in prep). This draft list of biodiversity associated with lantana is currently
undergoing review/revision (see DECC 2007).
Selecting sites for control
Although the determination of the biodiversity at risk from lantana is an important
step for conservation, information is needed on where this biodiversity is present
relative to the threat posed by lantana. This second step involves selecting and
ranking sites for control. Sites will be assessed, independent of land tenure,
using the following three criteria: (i) the ability to achieve effective lantana control
at the site; (ii) the actual impact of lantana at each site; and (iii) the condition of
the native species present and the physical condition of the site.
Site information is currently being collected, and the assessment and ranking of
sites will occur once the final list of species at risk has been finalised (DECC
2007). Site information, maps of lantana’s distribution or additional native species
at risk from lantana are being collected from land managers and can be lodged
via the lantana website (DECC 2007).
Monitoring the response of native species to lantana control
In order to assess the effectiveness of this approach a detailed monitoring
programme will be established at priority sites. Monitoring protocols will be based
on those being developed for bitou bush (see King and Downey in prep) and
contain a range of options to account for the full range of skills and resources of
land managers.
FUTURE DIRECTIONS
To date this project has lead to a significant increase in the number of species
known to be at risk from lantana invasion in Australia (see Turner et al. in prep).
This was not due to a sudden increase in the impact of lantana, but rather a
better understanding of the current situation. Such an understanding has arisen
from sourcing data from a multitude of people and resources.
In order to complete this project, assistance from land mangers is required with
respect to: (i) revising the interim list of species at risk from lantana, (ii) identifying
and ranking sites for control, and (iii) producing maps of lantana distribution. To
assist with this, the DECC has established a dedicated website for this project,
where the above information can be submitted (see DECC 2007). This project
also has initial funding for some of the priority sites. Funds will be allocated once
a list of priority sites has been established. Control of lantana at priority sites will
ensure that the conservation of biodiversity is maximised.
This project is supported by other strategic programmes, which are managed
under the Lantana WONS Programme. These include the Containment Zones
Project which co-ordinates management of isolated infestations outside of core
infestations. Integrated lantana management research is also being undertaken
to develop best practice management guidelines and decision support tools to
assist in lantana control. This project will also assist Catchment Management
Authorities in NSW to meet their targets of reducing the impacts of invasive
species (see O'Brien et al. these proceedings for further details).
TAKE HOME MESSAGES



There has been a significant increase in our understanding of the threat to
biodiversity posed by lantana.
A plan, similar to the Bitou TAP, is being developed that will identify
priority sites where control of lantana will provide the greatest biodiversity
benefit.
A website has been established to facilitate the development and
implementation of this plan, where land managers can provide further
input.
ACKNOWLEDGEMENTS
We thank the 199 workshop participants who were willing to share their
knowledge of the impacts of lantana and Andrew Clark of Biosecurity Qld
(formerly part of QLD Natural Resources and Water) who assisted in the
development of this project. Funds for this project have been provided by
Commonwealth Government, Defeating the Weeds Menace initiative.
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