Saturday, May 14, 2011

Fungi May be Responsible for Extinction of Some Forests

Photo courtesy: Dominic/CC

Pandas and tigers make better poster children for human impacts on biodiversity. But in the face of news like the massive recall of turkey meat with antibiotic resistant salmonella, it is worth remembering that altering the biodiversity at the smallest levels may have the largest impacts on our quality of life. A new study from the University of California Berkeley points to a fungi thriving after global warming as culprits in a massive extinction of trees.

The trees died off in the Permian extinction, which was probably triggered by massive volcanic activity. The gas and dust ejected into the atmosphere by volcanoes changed the global climate. Approximately 95% of marine organisms and 70% of life on land went extinct.

The scientists behind the report, published online in Geology, have re-evaluated filamentous (thread-like) microfossils preserved in Permian rock. Previous interpretations have suggested that these fossils derived from algae, or represent species that lived off of the decaying plants widespread in the Permian extinction.

The breakthrough came in comparing the Reduviasporonite fossils to a dormant or resting structure of the genus Rhizoctonia, which attacks the roots of modern-day plants and trees. The scientists suggest that the fungi spread widely, attacking and killing trees, which led to the erosion of topsoil and resulted in the fungal structures being washed into the sea and fossilized.

While the scientists acknowledge that many other forces cooperated as drivers of the massive Permian extinctions, Cindy Looy, UC Berkeley assistant professor of integrative biology, and her colleagues - Henk Visscher of the Laboratory of Palaeobotany and Palynology at Utrecht University in the Netherlands and Mark Sephton of the Impacts and Astromaterials Research Centre at Imperial College, London - believe that the fossil record demonstrates an aggressive soil-borne fungus contributed a key role in worldwide decline of forests in the Permian period. The researchers caution that "today's changing climate could also lead to increased activity of pathogenic soil microbes that could accelerate the death of trees already stressed by higher temperatures and drought."

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