Complex systems to stem the tide of invasion

The newly emerging science of complex systems may be our best weapon against invasion by exotic species, according to CSIRO researcher Mark Lonsdale.

Exotic species are one of the three major threats to Australia's biodiversity, says Dr Lonsdale, and cost the nation billions of dollars each year in lost agricultural revenue and ecosystem degradation.

CSIRO Entomology is launching a new project to investigate the processes which take place when invasions of weeds or pest animals take place, says Dr Lonsdale, head of CSIRO Entomology's Risk Analysis and Biosecurity project.

Dr Joslin Moore, a PhD graduate in invasion theory from Imperial College in London, will work with CSIRO Entomology to determine why some ecosystems are more susceptible to invasion than others, and which species in an ecosystem are particularly important in holding that ecosystem together.

"Exotic species have major impacts on the productivity and viability of our agricultural systems", says Dr Moore. "Developing a strategy to stem the flow of exotics is a key to any sustainable environmental future."

Dr Moore says that the answer may come from an unlikely source - the branch of applied mathematics called complex systems science, which CSIRO has identified as one of five emerging science disciplines that it will expand over the next few years.

She uses the world wide web as an example.

The world wide web is a special kind of network which is characterised by most nodes (i.e. web pages) being linked to only a few other nodes, which in turn are connected to other nodes via a few key nodes which have many links - the 'supernodes'. Networks with this structure can withstand random failures, since there is a low chance of being directly connected to any web page that fails. On the other hand, these networks can be devastated if the supernodes fail. Hence, identifying these supernodes and protecting them from failure or attack will greatly increase the overall robustness of the system.

Dr Moore says that ecosystems can be considered as natural networks of interactions between species (and the environment). "If we can identify the 'supernodes' in ecosystems then we would be in a much better position to focus our efforts against invasion and maybe stem the flow of exotics," says Dr Moore. "But the first step is to establish how network structure impacts on resistance and resilience to invasion and to identify the kinds of network structures that real ecosystems have".

Item provided courtesy of The CSIRO