Report on island ecosystems in Nature

Report on island ecosystems in prestigious international journal

A study published by Landcare Research scientist David Wardle in this week’s Nature highlights consequences of species loss in forest ecosystems.

Dr Wardle, Dr Olle Zackrisson and colleagues from the Swedish University of Agricultural Sciences report on a seven-year study spanning 30 islands in Sweden's desolate northern lakes.

The research team mounted a comprehensive investigation of the consequences of the disappearance of plant species or groups of plant species.

They measured different ecosystem properties such as total shrub cover and decomposition rates, as well as which particular species flourished in each area. The responses differed on islands of different sizes, probably because larger islands are more often struck by lightning and therefore experience more frequent forest fires, which reinvigorate ecosystems. The results underline the importance of individual context when evaluating ecosystem change.

The research on the consequences of local extinctions that Dr Wardle has conducted in Sweden is matched by a current study in New Zealand. Here he is examining the effects of local extinctions caused by ship and Norway rats after they invaded islands of different sizes, from the outer Hauraki Gulf to the Bay of Plenty. Rats have eliminated burrowing seabirds, reptiles, some insects and probably some plant species from these ecosystems.

The same ecosystem properties Dr Wardle reports from the Swedish islands are being measured in the New Zealand study. The New Zealand study is supported by the Marsden Fund, and Dr Wardle is working with colleagues from Landcare Research, and Dr Christa Mulder from the University of Alaska. The loss of species caused by deforestation, degradation and invasion of ecosystems is a worldwide problem.

The studies by Dr Wardle and his colleagues help build a comprehensive picture of the consequences of species loss. The studies can help identify which ecosystems are likely to be worst affected and will give some pointers to how and where effects of local extinctions could be mitigated.

ENDS

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