A new paper based on research in Queensland's Daintree Rainforest suggests 'termite transplants' may be necessary to help regenerating forests thrive.
Prof Lucas Cernusak and Dr Alex Cheesman, a Senior Research Fellow at James Cook University, were part of the study, led by scientists from the Cary Institute of Ecosystem Studies. They said it's counterintuitive to think that wood-eating termites could be welcomed into rainforests that have been painstakingly replanted.
"But we know that invertebrates like termites are essential for recycling nutrients and releasing carbon into the soil, and we worry that their slow recovery in plantings could hinder tree growth and health of young forests," said Dr Cheesman.
The scientists wanted to find out how well termites and fungi function in replanted forests, to help predict forest health and carbon sequestration rates.
The team placed blocks of wood in an old growth forest, part of JCU's Daintree Rainforest Observatory, as well as sites that had been replanted by Rainforest Rescue 4 and 8 years prior to the start of the study.
"For four years, we checked the wooden blocks every six months to see whether they had been discovered by fungi, termites, or both and then measured how quickly the blocks were decomposing," said study lead Dr Baptiste Wijas, a postdoctoral fellow at Cary Institute and visiting academic at the University of Queensland.
The scientists found that although wood decaying fungi quickly recovered in terms of both species and activity, termites – while present at all three sites – were slower to decay the wood blocks in the replanted forests than in the old growth forest, even 12 years after reforestation.
Lower rates of termite-driven decay can mean a slower return of nutrients to the soil, and less carbon injected into the recovering topsoil, which could harm forest health and future growth.
The scientists suggested a novel solution - transplanting deadwood logs from old growth rainforests to newer forests. These logs could bring in decomposers from elsewhere, helping to boost abundance and diversity, while also providing a food source for decomposers that are already present.
"A young, regenerating forest doesn't have a lot of deadwood in it," said Cary senior scientist Dr Amy Zanne. "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."
The team is also considering transplanting termite mounds into the forests along with the deadwood, "which is something that no one's really thought about either," said Dr Wijas.
The scientists said both approaches will likely be the subject of future research.
