Citizen science can help us protect the environment. With GPS data collected from volunteers, Helsinki is now able to modify the routes in its Central Park according to the paths that people actually use. People will be less inclined to make pathways of their own, and not accidentally damage the forest. Continuing our open science theme for Open Access Week, we present Silviya Korpilo. With the help of her research, the urban forest ecosystem can be preserved and developed to be more enjoyable and sustainable. Similar methods could be employed for any urban forest environment!