Modelling climate change impacts on sleeper and alert weeds

Citation

Land & Water Australia. 2008. Modelling climate change impacts on sleeper and alert weeds. [Online] (Updated April 28th, 2009)
Available at: http://lwa.gov.au/node/2565 [Accessed Tuesday 26th of April 2011 12:53:20 AM ].

Summary

This project will model the change in distribution of sleeper and environmental alert species due to climate change, and will assist in preparing a climate change weed risk map for Natural Resource Management regions across Australia.

Aims

The project aims to undertake a systematic analysis of all 28 environmental alert and all 17 agricultural sleeper weed species to determine the likely impact of climate change. This information will be combined to make a climate change weed risk map of NRM regions in Australia.

We now know that our climate will change in the coming decades. For this reason some weeds will have greater potential to spread in the future, whereas others might become less damaging than they are today. To address this question we are using CLIMEX, the leading program used to model species distributions, combined with OzClim which is used to model climate change scenarios. The project aims to undertake a systematic analysis of all 28 environmental alert and all 17 agricultural sleeper weed species to determine the likely impact of climate change.

Outcomes

The native distributions of each of the 41 species were mapped, both as on-line records of point locations, and the regions or countries where the plant is found. Maps were produced to show the introduced world distribution including collection records based on herbarium records in Australia. Most of the CLIMEX models have highly significant predictions to the observed distribution as determined by statistical analysis. Using the CLIMEX model, predictions of distribution were then made to Australia under the current climate and the eight climate change scenarios (Echam 3, Hadley 2, high and low emissions, 2030, 2070).

Under climate change there is a general shift southwards for most species (Figure 6), with the shift greatest for wet tropical species (over 1000 km), and much less for south coastal species (because of the lack of landmass to move into).

The most urgent recommendation from this work is that a new set of sleeper weed species needs to be identified for the north of Australia because of the vacuum that will be created by the displacement of species southwards, both native and introduced. Secondly, the predicted displacement of species under climate change enables the identification of management strategies for each species. This could include developing east-west quarantine barriers along potential migration routes. While some of the alert and sleeper species are evidently of low threat, the analysis of potential distribution identifies certain species, such as Acacia karroo, Retama raetam and Equisetum arvense that could become major problems under any climate scenario and should be managed accordingly.

Background

Scientists are now convinced that climate is changing as a result of human-induced global warming and will continue to do so in the coming decades. Changes in climate will provide some weeds with greater potential to spread in the future, whereas others might become less damaging than they are today because of decreased potential growth and survival.

Sleeper weeds are those plants from overseas that have currently established only small populations in Australia but that have the potential to spread widely and affect agriculture or the natural environment, while alert weeds are those that are in the early stages of establishing and have the potential to pose a significant threat to biodiversity. Clearly the reaction of both sleeper and alert weeds to climate change is of interest to future management of the landscape.

This project uses climate modeling to predict the potential growth and survival of sleeper and alert species of plants in different locations, based on their responses to temperature, moisture and light.