Invisible fungi crucial for rainforest diversity

Dec 21, 2011 By Tamera Jones
Invisible fungi crucial for rainforest diversity
Fungal network and leaf litter mass.

A complex network of fungi in the lower canopy could be one reason tropical rainforests are home to so many different types of insects, spiders and centipedes, say scientists.

They found that nearly half of these creatures – called arthropods – are largely dependent on an almost-invisible network of fungi that traps dead leaves that have fallen from the upper canopy.

When the researchers removed the fungi, both the numbers and diversity of arthropods dropped dramatically.

The findings could help conservationists figure out how to retain some level of arthropod diversity in managed landscapes like oil palm plantations, or logged forest.

The fungi branch through the lower canopy extending from the forest floor up to around 30 metres high, catching falling leaves wherever their strands go.

"These fungi are everywhere, and form a messy tangle in the forest understory. You can't really see it until you look for it. You're always looking past it, moving it out of the way as you walk through the forest," explains Dr. Jake Snaddon from the University of Oxford, lead author of the study.

This could be why, up until now, its importance was almost entirely overlooked.

Scientists have an idea that the extraordinary numbers and types of arthropods in is in some way connected to the biological complexity of this habitat. But exactly what contribution these fungal networks make in supporting lots of different types of insects, spiders and millipedes isn't well understood.

Invisible fungi crucial for rainforest diversity

So together with a team of researchers from the UK and Malaysia, Snaddon decided to find out. They started by analysing how builds up in the canopy.

"Nobody had really looked at the part this system had to play before now," Snaddon says.

"Initially when I started looking, I could see the leaf litter, but I had to look a lot harder to see the actual fungi."

The fungus attaches itself to living vegetation, using it as a support network. When dead plant matter falls into the network, the fungus send out tiny filaments known as hyphae to grow into it and break it down.

The researchers found that this network of fungi traps more leaf litter than any other known rainforest litter-trapping systems like fern mats or bromeliads. They estimate that the network traps around 260 kilograms of leaf litter per hectare, compared with around 100 kilograms per hectare caught by bromeliads.

When they tried removing the network from a small section of Malaysian rainforest, the numbers of arthropods fell by 70 per cent and the variety of species dropped by nearly 60 per cent.

'These fungi play a crucial role in the maintenance of canopy diversity, making a huge contribution to the abundance of insects, and a whole range of arthropods,' says Snaddon.

It seems that these litter-trapping provide both food and a home for a wide variety of rainforest organisms. Not just that, but they probably provide a means of connection for living far apart from each other.

"It acts like a huge network, connecting different parts of the together. It's possible that arthropods use it like a superhighway to get from place to place," says Snaddon.

"We often focus on the more showy forest species, but this study demonstrates that all species are important," he adds.

The next step will be to figure out if these networks also exist in degraded habitats such as palm oil plantations and logged areas of forest. 'They need consistently damp conditions, which you might not find in degraded areas,' Snaddon says.

The study is published in Biology Letters.

Explore further: Rare albino sparrow spotted in Australia

More information: Jake L. Snaddon, et al., Biodiversity hanging by a thread: the importance of fungal litter-trapping systems in tropical rainforests, Biology Letters, published 21 December 2011, doi:10.1098/rsbl.2011.1115

Related Stories

Team sequencing 1,000 fungal genomes

Nov 07, 2011

A 79-year-old collection of fungal cultures and the U.S. Forest Service's Northern Research Station are part of a team that will sequence 1,000 fungal genomes in the next 5 years.

New parasitic fungi found that turn ants into zombies

Mar 04, 2011

( -- Scientists from the US and UK have discovered four new species of parasitic fungi in the Brazilian rainforests. The fungi attack four distinct species of ants and release mind-altering chemicals ...

Recommended for you

11 new species come to light in Madagascar

3 hours ago

Madagascar is home to extraordinary biodiversity, but in the past few decades, the island's forests and associated biodiversity have been under greater attack than ever. Rapid deforestation is affecting the ...

Birds 'weigh' peanuts and choose heavier ones

May 23, 2015

Many animals feed on seeds, acorns or nuts. The common feature of these are that they have shells and there is no direct way to know what's inside. How do the animals know how much and what quality of food ...

Estuaries protect Dungeness crabs from deadly parasites

May 22, 2015

Parasitic worms can pose a serious threat to the Dungeness crab, a commercially important fishery species found along the west coast of North America. The worms are thought to have caused or contributed to ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.