Dead trees are nothing new in the Australian landscape, but last summer was particularly severe.
Following weeks of orange haze and thick black smoke caused by bushfires that ravaged the country, an estimated 21% of the total area covered by forests – excluding Tasmania – was burnt.
Add to this the ongoing threat of drought, heatwaves, insects and fungal pathogens, and it’s easy to see why the death of native trees is very real problem – and one that is hard to monitor.
Help is at hand, however. Amateur tree sleuths across the country have been recruited by the Dead Tree Detective citizen science project to collect valuable evidence.
“It sounds a bit grim,” admits project leader Belinda Medlyn from Western Sydney University (WSU), “but knowing where and when trees have died helps us to work out what the cause is, identify trees that are vulnerable, and take steps to protect them.”
This information can help researchers understand the reason for tree death, the species that are particularly vulnerable, and what can be done to protect them.
“The more information on tree deaths we can collect, the more we’ll be able to understand what leads to tree deaths – and to what extent trees might be able to recover,” Medlyn says.
The project started in 2018 out of WSU and the University of New England. At the time, the researchers were trying to predict where tree death would occur following drought by looking at what species died during the Millennium Drought.
“The only problem was, as we soon realised, nobody tracks tree deaths in Australia! There was no information available at all about what died, meaning we couldn’t tell if our predictions were any good or not,” Medlyn says.
At the start of 2019, just when the drought in NSW was beginning to bite, the team launched its new Detective project.
“We had some really dramatic photos submitted, from landholders, farmers, tourists – all kinds of people who were just really startled by what they were seeing,” Medlyn says.
“The drought of 2019/20 has pretty much broken now, so we are seeing many fewer cases of tree death from drought. However, tree deaths from other causes are continuing, and we’d love to get photos to help us keep tracking what’s happening.”
Participants can also keep up to date with reports across Australia, or in a specific area using the data section of the website, which they can also use as a basis for their own observations.
“Interestingly, many of the trees whose leaves all turned brown over the summer ended up surviving; many folks have contacted us to say that the trees they saw are now growing new leaves,” Medlyn says.
As the climate warms, it’s possible that our native trees become more resilient to warmer weather; it’s also possible they might not be able to cope, with more information needed to work out the limits of their resilience.
“As scientists we are only a handful of individuals and can’t see what’s happening across Australia. Ordinary folk can help us by being our eyes on the ground.”