By Melanie Friedel, American Forests

An infected tree. Credit: Evelyn Simak

Interested in other nature-friendly apps for your iPhone? Check out these 7 free apps for Hikers, Birders and Nature Lovers.

What if you could go Pokémon hunting and save an animal for every Pokémon you catch? Well, that game hasn’t been created yet. But this one has! You can save a tree just by playing a game called Fraxinus: the app that can save the dying ash tree population of the UK.

Players earn points walking through forests and matching up leaf color sequences they see on trees with images on their phones. Each pattern corresponds to a specific genetic sequence, and behind the screens, scientists examine the genetic makeup of trees, analyzing what makes some trees more vulnerable to the fatal fungal infection and others more resistant. This also sends the scientists the locations of each examined tree, helping them build a database mapping the health of their forests and where interventions are necessary.

The name “Fraxinus” comes from the ash tree’s Latin name, Fraxinus excelsior. When Fraxinus players match up their ash tree with an option on their screen, they submit a photo and tag it with an AshTag. As more players run into the same tree and tag it again and again, each player who has previously tagged it can track its progress over time, while scientists simultaneously watch the disease progress in individual trees and devise a prevention plan.

The disease is spreading quickly through both the wind and mechanical transportation of infected trees, killing younger trees shortly after infection and weakening older trees that then become vulnerable to other threats. Almost 42% of all 10-square-kilometer areas in the UK have already been affected. With such a wide spanning area affected by Hymenoscyphus fraxineus, the fungus causing the dieback, it might seem impossible to collect enough data on the genetic sequences of affected trees, but with thousands of players inputting data every day, it’s finally feasible to find a solution.

With enough tree photos, locations, and pattern matches submitted by players, the scientists working on the project hope to find a gene pattern that makes ash trees resistant to the fungus and repopulate the forests with this variation. So if you feel like being productive and saving a forest, get up, go out, and start playing on your phone!