Termites play an unexpected role in rainforest revival

Termites are often overlooked in rainforest restoration, where the focus is usually on planting trees. But what if the key to a thriving forest lies not in the canopy above, but in the soil below – and in the insects that crawl through it?

A new study reveals that termites, often seen as pests, might actually be essential allies in helping young rainforests flourish.

Scientists from the Cary Institute of Ecosystem Studies and the University of Queensland in Australia have found that these tiny decomposers are missing – or at least lagging behind – in forests that have been replanted, even more than a decade after restoration began.

Forests need more than trees

“People tend to think that by just planting a diversity of trees, these rainforests will regenerate,” said Baptiste Wijas, a postdoctoral fellow at Cary Institute and visiting academic at the University of Queensland.

“But it’s worth thinking about, should we actually be putting in other organisms as well, to restore other ecosystem processes that help the forest function? In the context of rainforest regeneration, no one really thinks about it at all.”

That question matters more than ever. As more land is reforested in efforts to combat climate change and restore ecosystems, it’s crucial to understand what makes a forest actually function.

Decomposers like termites and fungi play a critical role in cycling nutrients and carbon. Without them, the soil might lack the resources young trees need to grow.

Testing the forest floor

To understand how well decomposers were rebounding, the research team set up a simple but telling experiment. They placed wooden blocks in three different forest settings in Australia’s Daintree Rainforest. One was a pristine old-growth forest.

The other two were replanted sites – one restored in 2010, the other in 2014 – on land that had been cleared for agriculture decades ago and later abandoned. The replanting was carried out by a nonprofit organization called Rainforest Rescue.

For four years, the team checked on the wooden blocks every six months. They looked for signs of fungi, termites, or both, and tracked how fast the wood was breaking down.

A wet and wild challenge

The fieldwork was anything but easy. “You’re sweating all the time, and there are plants that want to attack you everywhere,” said Wijas.

In one year alone, the team faced a series of extreme weather events – drought, floods, fires, and “a zombie cyclone that caught us twice,” said Cary Institute senior scientist Amy Zanne. “It was an epic, biblical year.”

Despite these challenges, the team made a surprising discovery. They expected that termites would be thriving in all the rainforests and that fungi would struggle more in the younger sites. But the results were the opposite.

Fungi thrive while termites struggle

Fungi were resilient. They performed almost as well in the replanted forests as in the old-growth site, though they were a bit slower in the youngest forest.

Termites, however, were another story. While they were present at all three sites, they decomposed wood at a much slower rate in the replanted forests. Even 12 years after reforestation began, the termite-driven decay lagged behind.

The researchers suggest several possible reasons: termite colonies in the replanted areas may be fewer, smaller, less diverse, or less mature.

That’s a problem, because slow decomposition can mean nutrients and carbon aren’t returning to the soil quickly enough. And that could stunt forest growth.

A radical idea: Importing insects

To fix the problem, the scientists have a bold proposal. They suggest bringing logs from old-growth forests into younger forests to introduce decomposers and give existing ones more to eat.

“A young, regenerating forest doesn’t have a lot of deadwood in it,” Zanne explained. “So if you bring in these logs, you’re giving them some food to tide them over while they wait for parts of trees to start falling down.”

They’re also thinking even bigger: what about transplanting entire termite mounds? “That’s something that no one’s really thought about either,” said Wijas.

Rethinking termites in forests

Convincing forest managers to welcome termites into their restoration plans won’t be easy.

“Many people – forest managers included – don’t really like termites,” said Wijas. “But they play an important role in having a healthy forest.”

Zanne pointed out that most termites get a bad rap for no reason. “Only about 3% of termites are known to damage human homes. Very little is known about the other 97%.”

More than just decomposers

In fact, termites might be doing even more good than we think.

“We think termites might be locking up carbon in their nests,” said Wijas. “When they eat wood, they’re not able to digest all of it, and so the feces they use to build their nests could be quite carbon-rich. They may even lock up more carbon than they emit, but we just don’t know yet.”

Termites may also help trees grow by partnering with nitrogen-fixing bacteria, which convert nitrogen into a form plants can use.

“Termites and fungi are absolutely critical to forest function,” said Zanne. “It would be interesting to see who else returns to the regenerating forests if the termites are there – perhaps ants, lizards, and gliders that eat termites. Right now we just don’t have any idea whether these organisms are coming back in these systems.”

As the search continues for ways to speed up rainforest recovery, termites may prove to be unlikely but vital allies. The next time we think about rebuilding a forest, we might want to think beyond trees—and start thinking about termites too.

The full study was published in the Journal of Applied Ecology.

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