A forest, as anyone who spends time in one will know, is a lot more than just trees. These ecosystems support a massive number of different organisms living together in complex webs of interdependence.

But when people try to regrow a forest, they often just plant trees. That single-minded focus might be slowing a return to the rhythms of growth and decay that shape natural forests.

“People tend to think that by just planting a diversity of trees, these rainforests will regenerate,” said Baptiste Wijas, an ecologist and postdoctoral researcher with the Cary Institute of Ecosystem Studies. “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?”

One ingredient people should consider adding to the replanting mix isn’t a plant at all. It’s termites, according to new research by Wijas in a north Australian rainforest.

Termites as well as fungi are critical to breaking down dead wood, helping to control how quickly fallen trees are digested and turned into carbon that can sink into the soil or float into the air.  Some of that carbon might wind up stored in termite nests. The insects are also associated with bacteria that fix nitrogen, a critical nutrient for growing plants. In some cases, they can churn up soil into massive mounds . “Termites and fungi are absolutely critical to forest function,” said Amy Zanne, an ecologist and senior scientist at the Cary Institute, who worked with Wijas.

The role of both termites and fungi in replanted rainforests takes on particular importance as old-growth rainforests are being felled at an alarming rate. These second growth forests—whether planted or naturally recovering—are increasingly seen as critical to tackling the joint crises of biodiversity loss and climate change. So understanding the drivers shaping their regrowth can help inform the ways people try to help along the revival.

It turns out these recovering forests also hold some scientific surprises. Wijas and Zanne original thought they would find differences between fungi in old-growth and recovering forests, while research from South America suggested termites were just as active in both kind of places.

But that was before they put chunks of wood into three different parcels of Australian rainforest. Some wood was left on the ground of a pristine Australian rainforest dominated by red oaks and silver ash trees. Other test wood was left on two parcels of former farmland nearby that had been logged around 1900, then replanted with native trees in 2010 in one case and 2014 in the other.

Over the course of four years, the scientists repeatedly selected some of the wood to see how much it had broken down, what kind of fungi were growing in it, and how much termites had eaten.

To their surprise, the fungal communities taking up residence in the wood were the same in the old growth and new forests. While fungi were a bit slower to break down wood in the newest planting site, fungal decomposition in the “older” replanted area had reached rates similar to the uncut forest.

There was also no difference between the forests when it came to signs that termites had discovered the new wood—as evident from live termites and other clues.

The big difference turned up in how quickly these termites devoured the logs. In the old growth forest, experimental wood colonized by termites was gone by the third year. But after four years, around 25% of the wood remained in the second-growth areas, the researchers reported last week in the Journal of Applied Ecology.

The scientists aren’t sure why these bugs showed less of an appetite for the wood in the newer forests. It could be that less mature colonies there had fewer or smaller termites, meaning they took less of a bite from the forest.

The findings prompted the scientists to suggest that people replanting rainforests also consider an additional step: a termite transplant.

That could come in the form of decaying logs brought from more intact forests. “A young, regenerating forest doesn’t have a lot of deadwood in it,” said Zanne. “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.”

People could even consider transplanting entire termite mounds with their occupants. “which is something that no one’s really thought about either,” said Wijas.

Of course, when you consider the logistics of moving a massive mound of earth teaming with angry insects, maybe there’s a reason why that hasn’t happened. Yet.

Wijas, et. al. “Decadal recovery of fungal but not termite deadwood decay in tropical rainforest.” Journal of Applied Ecology. May 6, 2025

Photo: Althepal/ Wikimedia