Climate-Induced Range Shift and Risk Assessment of Emerging Weeds in Queensland, Australia

Anticipation and identification of new invasive alien species likely to establish, spread and be impactful in a landscape, especially in response to climate change, are consistently a top priority of natural resource managers. Using available global bioclimatic variables limiting plant distributions, we employed maximum entropy (MaxEnt) as a correlative species distribution model to predict the current and future (2041-2060 and 2061-2080) distribution for 54 emerging weed species of different growth forms for the State of Queensland, Australia. Overall, the model predictive performance was excellent, with area under the curve (AUC) and the true skill statistic (TSS) averaging 0.90 and 0.67, respectively. Based on distribution records, the emerging weed species sorted out along environmental (climatic) space-with trees and succulents, each at the two ends of the continuum, while grasses, herbs and shrubs were distributed between the two extremes. Temperature seasonality and minimum temperature of the coldest month were the main driver variables that accounted for differences in climatic preference among the focal species and/or plant growth forms. Range shifts were predicted for many species in response to climate change; overall, habitat range increase will occur more often than range contraction and especially more so in trees compared to all other plant growth forms. Range stability was least in succulent weeds. In general, under climate change, the majority of the invasion hotspot area was projected to remain geographically stable (76.95%). Far northern Queensland (especially the Gulf of Carpentaria and Cape York Peninsula areas) and the coastal communities along the eastern seaboards of the State are the hotspots for emerging invasive alien species to establish and expand/contract in response to climate change. Based on observed and potential ranges, as well as species response to climate change, we derived an index of risk and hence statewide prioritisation watch list for management and policy of the emerging weeds of Queensland.