Planting forests while growing protein-rich food seems like a win-win, so are there any downsides? Lynne Boddy, professor of fungal ecology at Cardiff University, believes that mycoforestry "absolutely" has the potential to produce significant food crops while sequestering carbon. However, she advocates for "enormous care" in this. "In my mind, whenever we inoculate something, it has to be locally sourced," he says of the fungi. "There is the concern of an invasive genotype if it comes from elsewhere. Even if it comes from Great Britain, and you are only planting the same thing in one area, there is a concern of diluting the gene pool. It is also likely to decrease the diversity of local species".

Thomas says that these are valid questions, but he points out that this project is focused on the use of fungal species native to the planting area, and with less aggressive strains than those already inoculated by many nurseries to encourage the growth of the tree, although he acknowledges that it could be potential. for another company to seek to use a form of genetic modification in the future, which must be regulatory approval.

There is also the question of what happens to the trees. If they are left standing or produce wood that is used as construction material, then that pulls carbon from the atmosphere for a long time. But if the wood ends up decomposing or being burned - as is often the case with Christmas trees - then most of the carbon removed could end up back in the atmosphere. Even so, this cycle also produces protein with a net carbon footprint.

This process could make future Christmas trees more sustainable, Jump believes. The conventional way of growing Christmas trees is "a pretty inefficient system, if you look at it from a carbon perspective," he says. "You can soak the carbon in the tree, but then drag the trees after Christmas. Getting the fungi associated with the Christmas trees is actually a pretty good way to reduce the impact of the carbon."

A milk cap mushroom.Courtesy of Mycorrhizal Systems Ltd.

But the main question should be, how do the mushrooms taste? "Unbelievable," says Thomas. Some of their common names suggest their taste and appearance, including the "delicious milk cap" and - Jump's favorite - "penny buns". "They're so cute," she explains. But Thomas won't be drawn into picking a favorite. "I love them all," he says, laughing. "There are too many really cool ones."