Sweden's tidy forests hide a dark secret

Sweden's meticulously managed forests, often seen as a symbol of environmental care, harbor a hidden deficit: a critical lack of dead wood. While production forests are growing, they are failing to provide the necessary habitat for many endangered species.

“

Dead wood lives.

A new study by researchers at the Swedish University of Agricultural Sciences (SLU) and Finland's Natural Resources Institute has significantly raised the bar for what is required to support vulnerable biodiversity. They found that between 40 and 50 cubic meters of dead wood per hectare are necessary to give red-listed mosses and wood-decaying fungi a 50% chance of survival. This is a stark contrast to the current average of less than 8 cubic meters per hectare found in Swedish production forests, according to the National Forest Inventory.

These findings challenge previous benchmarks in nature conservation, which suggested 20 cubic meters per hectare was sufficient. The study focused on the specific needs of red-listed and more demanding species within commercial forests, rather than general species richness. The current volume is less than 20% of the required amount.

“

Most previous studies have looked at general species richness. We have instead studied the red-listed and more demanding species out in our ordinary production forests.

Furthermore, the quality of the existing dead wood is also a concern. Evaluations by the Swedish Forest Agency indicate that the increase in dead wood is primarily composed of smaller stems and harder wood resulting from storms, drought, and bark beetle infestations. Many threatened species, however, depend on larger, decaying logs, which are now mainly found in old-growth forests that have not been clear-cut. The continued loss of these valuable natural forests is identified as the greatest threat to the forest's biodiversity.

“

The greatest threat to the forest's biodiversity is that the last valuable natural forests continue to disappear. We cannot afford to sacrifice them, because there are no guarantees that the species will return just because you replant.