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Abstract
Invasive weeds inflict significant harm on native species, ecosystem processes, and natural disturbance regimes. When managing these weed threats, some of the most useful tools are the outputs of predictive distribution models. As they supplement existing distribution data to assess where in the landscape is most susceptible to weed invasion, they allow for more efficient weed management because the areas most suited to weed species may be targeted for control.
This research develops a habitat suitability model for the weed lantana (Lantana camara L. sensu lato) in a portion of the Greater Blue Mountains World Heritage Area at present and under forecast warmer climates. A generalised additive model (GAM) is used, which fits the regression curve used for prediction to the calibration data themselves and allows for an exploration of which environmental conditions favour lantana as well as where in the landscape is most suitable for the weed. Temperature was positively correlated with suitable habitat and explained over 90% of the variation in lantana presence predicted by the model. 15% of the study area was found to be suitable for lantana at present, with this figure reaching 58% after a simulated 3°C rise in temperature. Mapping habitat suitability across the study area allowed for the identification of five distinct pathways for lantana to further invade the Blue Mountains.
Responding to calls for the integration of weed management with biodiversity conservation, the research also integrates the habitat suitability model with information regarding the distribution of vegetation communities and endangered species in the Blue Mountains. Thirteen native vegetation communities were found to have more than 20% suitable habitat for lantana at present, and an additional three contained more than 80% suitable habitat after a simulated 3°C rise in temperature. Five of these communities are listed as threatened under relevant legislation and harbour at least 27 endangered species, placing additional urgency on their conservation.
This research has successfully used modelling techniques to identify areas for targeted weed management integrated with biodiversity conservation. The methods are easily adaptable to other weeds and regions and could thus be used to illustrate the comprehensive threat weeds pose to Australia’s biodiversity.