PLANTS BEHAVING BADLY A Zero Tolerance Policy?

Aliens are mostly from deliberate introductions in the Australian wet tropics, 51 of 53 environmental weeds were deliberate imports as mostly garden and pasture plants.in the Australian wet tropics, 51 of 53 environmental weeds were deliberate imports as mostly garden and pasture plants.

Deliberate introductions -- spectacular failures between 1947 and 1985 more than 460 exotic pasture grasses and legumes were trialed in northern Australiabetween 1947 and 1985 more than 460 exotic pasture grasses and legumes were trialed in northern Australia all 460 have now become naturalisedall 460 have now become naturalised only 21 proved usefulonly 21 proved useful 60 ended up becoming problem weeds, including 20 of the 21 useful species60 ended up becoming problem weeds, including 20 of the 21 useful species

The rate of naturalisation is increasing Despite supposedly knowing better and with better controls, the rate of recent incursions is over double the annual rate for the last 100 years.Despite supposedly knowing better and with better controls, the rate of recent incursions is over double the annual rate for the last 100 years.

Horticulture is the major culprit 30% of the worst noxious weeds and 7 of the 18 worst environmental weeds were originally introduced as garden plants.30% of the worst noxious weeds and 7 of the 18 worst environmental weeds were originally introduced as garden plants. species that naturalised in Australia between were introduced as:species that naturalised in Australia between were introduced as: - garden ornamentals 65%, - agriculture 7% - seed contamination 2%.

Weeds are yesterdays fashion statement Most of the weeds of horticultural origin are no longer in horticultureMost of the weeds of horticultural origin are no longer in horticulture We introduce new garden plants as soon as the older ornamentals fall out of favourWe introduce new garden plants as soon as the older ornamentals fall out of favour

Tomorrows weeds are already here even if Australia closed its doors on all imports today, our alien plant numbers would still increaseeven if Australia closed its doors on all imports today, our alien plant numbers would still increase thousands of aliens have already entered the countrythousands of aliens have already entered the country sleepers are all around us, in our gardens, on our farms and plantations, in laboratories and aquariasleepers are all around us, in our gardens, on our farms and plantations, in laboratories and aquaria most garden plants are wilful, wild organisms - survive and reproducemost garden plants are wilful, wild organisms - survive and reproduce

The Darwin example - Mimosa pigra introduced into the gardens in the 1880’sintroduced into the gardens in the 1880’s a sleeper for nearly 100 yearsa sleeper for nearly 100 years in the 1970’s it exploded into the wetlandsin the 1970’s it exploded into the wetlands now covers about 80,000 hectares of World Heritage listed wetlandsnow covers about 80,000 hectares of World Heritage listed wetlands

The Darwin example - Mimosa pigra now number 10 on the list of declared ‘Weeds of National Significance’now number 10 on the list of declared ‘Weeds of National Significance’ our conservation effort in the Botanic Gardens pales into insignificance against the monetary and environmental costs of one introduced alienour conservation effort in the Botanic Gardens pales into insignificance against the monetary and environmental costs of one introduced alien

Botanic Gardens – part of the problem – part of the solution weed researchers have identified many research prioritiesweed researchers have identified many research priorities some are beyond the remit of Botanic Gardenssome are beyond the remit of Botanic Gardens there are some that gardens can be involved withthere are some that gardens can be involved with

Botanic Gardens - a redistribution of effort Detecting new weeds - early alert systemsDetecting new weeds - early alert systems Research into weed life historyResearch into weed life history Identification of ‘sleeper’ weedsIdentification of ‘sleeper’ weeds Weed Risk Assessment modelsWeed Risk Assessment models Education and community engagementEducation and community engagement

Weed Risk Assessment the identification of potentially invasive species prior to importationthe identification of potentially invasive species prior to importation the potential seriousness of a new outbreakthe potential seriousness of a new outbreak potential sleeperspotential sleepers identification of knowledge gaps in individual weed speciesidentification of knowledge gaps in individual weed species

Species characteristics  History of invasive behaviour elsewhere  Relatedness to species that show invasive behaviour  Climatic match between original range and proposed introduction area  Noxious and undesirable traits  Biological attributes of the plant itself

Modified Weed Risk Assessment Schemes particular ecosystems e.g. adaptation of the New Zealand scheme for the insular terrestrial flora of the Galapagos Islands;particular ecosystems e.g. adaptation of the New Zealand scheme for the insular terrestrial flora of the Galapagos Islands; particular life forms e.g. adaptation of the New Zealand scheme to aquatic weeds;particular life forms e.g. adaptation of the New Zealand scheme to aquatic weeds; particular vegetation types e.g. woody invaders in South African fynbos flora;particular vegetation types e.g. woody invaders in South African fynbos flora; particular bioregions e.g. adaptation of the Australian scheme to the Wet Tropics bioregion of northern Australia.particular bioregions e.g. adaptation of the Australian scheme to the Wet Tropics bioregion of northern Australia.

Weed Risk Assessment: A matter of scale discriminate between invaders and non-invaders – often over 80% success ratediscriminate between invaders and non-invaders – often over 80% success rate does not quantify the magnitude or type of impacts.does not quantify the magnitude or type of impacts. as a pre-import tool, impact is not measured in the target countryas a pre-import tool, impact is not measured in the target country national level WRA models are unlikely to be well adapted for use at a more local scale.national level WRA models are unlikely to be well adapted for use at a more local scale. below the national scale, the focus of WRA becomes increasingly on assessing the impact of aliens and prioritising response actions.below the national scale, the focus of WRA becomes increasingly on assessing the impact of aliens and prioritising response actions.

Weed Risk Assessment in Botanic Gardens the criteria need to become more focused on the local environmentthe criteria need to become more focused on the local environment Botanic Gardens should focus on assessing horticultural plants as potential environmental weedsBotanic Gardens should focus on assessing horticultural plants as potential environmental weeds as the geographic scale becomes more local, the data, the research and resourcing requirements to undertake and implement a WRA may increase.as the geographic scale becomes more local, the data, the research and resourcing requirements to undertake and implement a WRA may increase. However, if Gardens focus on the environmental weed issue, it appears the model can be made relatively easy to use.However, if Gardens focus on the environmental weed issue, it appears the model can be made relatively easy to use.

Weed Risk Assessment in Botanic Gardens the Australian national WRA system requires information against 90 criteriathe Australian national WRA system requires information against 90 criteria a model in a Botanic Gardens has only 30 criteriaa model in a Botanic Gardens has only 30 criteria horticultural ground staff are enthusiastic about being involved and with having a system that they can implementhorticultural ground staff are enthusiastic about being involved and with having a system that they can implement the process recognised the need to develop a data base to capture staff observational information.the process recognised the need to develop a data base to capture staff observational information.

Education and Community Engagement “No plant is inherently ‘bad’, but rather that gardeners sometimes make poor choices” alien species becomes a question of gardening ethics – ‘What plants to grow?’alien species becomes a question of gardening ethics – ‘What plants to grow?’ gardeners must develop a new ethos of ecological responsibility in what they plantgardeners must develop a new ethos of ecological responsibility in what they plant Botanic Gardens also send a strong public message that what they display are good garden plantsBotanic Gardens also send a strong public message that what they display are good garden plants

A national approach to garden escapees A national approach to garden escapees involves local, state, and federal government agenciesinvolves local, state, and federal government agencies involves the plant industry and horticultural mediainvolves the plant industry and horticultural media wide dissemination of listed ‘Garden Thugs’wide dissemination of listed ‘Garden Thugs’ a black list of 958 speciesa black list of 958 species on-going assessment of weedy potential of garden plantson-going assessment of weedy potential of garden plants

Garden Plants Under the Spotlight education programs encourage replacement of garden plants of weedy concern with non- weedy alternativeseducation programs encourage replacement of garden plants of weedy concern with non- weedy alternatives

Garden Plants Under the Spotlight the strategy urges adoption of self-regulation within the industrythe strategy urges adoption of self-regulation within the industry industry support includes a voluntary ban on selling the worst behaving garden plantsindustry support includes a voluntary ban on selling the worst behaving garden plants nurseries should know the species that are ‘weedy’ in their area and not stock them.nurseries should know the species that are ‘weedy’ in their area and not stock them.