SCHIERKE, Germany — Several retirees, a few millennials, a local couple and a technology specialist who saved overtime hours to take a day off from work gathered around a pile of birch twigs sprouting leaves on one end and a tangle of fine roots at the other.

One by one, they grabbed a bundle of the seedlings and picked their way through snow-clad fallen branches, searching for holes that had been dug into the black earth on the edge of the Harz National Park in the heart of Germany.

“You want to cover them well, and don’t leave any air pockets beneath the roots,” cautioned Olaf Eggert, the ranger responsible for this stretch of woods, as he held a seedling aloft, his forefingers scissored about halfway up the stem to demonstrate how deep in the earth the young trees must be buried to ensure their survival until spring.

More than 444,000 acres of forest in Germany are distressed or have died in recent years, according to government data. Across the country, Germans are worried about the survival of their forests, a natural treasure that is considered part of their identity and a source of their wealth.