Fungi Regulate Rainforest Diversity

January 2014

Fungi Regulate Rainforest Diversity 

Link: http://www.sciencedaily.com/releases/2014/01/140122133827.htm

     Oxford University led research that found that fungi control diversity in rainforests by making dominant species victims of their own success. Fungi spread quickly between tightly bunched plants of the same species, preventing them from dominating and allowing a wider range of species to thrive.

     Dr. Owen Lewis of Oxford University's Department of Zoology, the man who led the study, reported, "Seedlings growing near plants of the same species are more likely to die and we now know why. It has long been suspected that something in the soil is responsible, and we've now shown that fungi play a crucial role. It's astonishing to see microscopic fungi having such a profound effect on entire rainforests. Fungi prevent any single species from dominating rainforests as they spread more easily between plants and seedlings of the same species. If lots of plants from one species grow in the same place, fungi quickly cut their population down to size, leveling the playing field to give rarer species a fighting chance. Plots sprayed with fungicide soon become dominated by a few species at the expense of many others, leading to a marked drop in diversity."

     The study looked at seedling plots across 36 sampling stations in the Chiquibul Forest Reserve, Belize, and was published in Nature. It was carried out by scientists at Oxford University and Sheffield University and funded by the Natural Environment Research Council (NERC).

     Every week for 17 months, researchers sprayed plots with water, insecticide, or fungicide. They found that the fungicide 'Amistar' hindered diversity, reducing the effective number of species by 16%. Although the insecticide changed the arrangement of surviving species, it did not have an overall impact on diversity.

     Scientists believed that fungus-like microorganisms called oomycetes may also play a part in regulating rainforest diversity, but after the study, this theory proves to be unlikely. "Oomycetes are potent pathogens that can cause seeds and seedlings to rot, and were responsible for the 1840s potato famine," said Professor Sarah Gurr, formerly of Oxford University.

     The findings show that fungi play a vital role in maintaining the biodiversity of rainforests, preventing a few highly competitive species from dominating. This helps explain why tropical rainforests are more diverse than forests in temperate countries.