Strong winds sweep over the Rhön, a vast region of rolling, forested hills and pastureland in central Germany. Undeterred, Stefan Zaenker, leading a group of four volunteers, runs through his checklist alongside a forest road. Are rubber boots disinfected to prevent introducing potentially harmful microorganisms into the wetland? Are the team app and GPS functioning correctly? Have enough flags been packed?

When all is in order, Zaenker, 56, leads the group into a soggy alder forest. Its mission for the day: to locate and map as-yet-undiscovered springs and document any species inhabiting them.

A senior conservation official for the state of Hesse, Zaenker considers springs so important for human life and biodiversity that he — along with volunteers from the Hesse Association for Cave and Karst Research — spends much of his spare time conducting large-scale searches for them in the Rhön, which includes the German states of Bavaria, Thuringia, and Hesse, and in a nearby […]