Key Highlights
- Who: Interdisciplinary team from the Friedrich-Schiller-Universität Jena.
- Where: Saale-Elster-Sandsteinplatte-Observatorium (south of Jena).
- What: Investigation into the filtering effect of forest floor plants.
- Result: Mosses effectively prevent excess nitrogen from entering the groundwater.
Jena (09.02.2026) – Anyone walking through the forests around Jena usually enjoys the rustle of leaves and the majestic treetops. However, the real work for a healthy ecosystem and clean water often takes place unnoticed one level below. Scientists from the Friedrich-Schiller-Universität Jena are now drawing attention to the forest floor with new research findings—and providing compelling arguments as to why we should pay more attention to mosses.
Small Plants, Big Impact
Nitrogen is a double-edged sword: it is indispensable for plant growth, but an excess can have serious consequences for the environment. If too much nitrogen passes through the soil into deeper layers, it threatens to contaminate the groundwater and adjacent bodies of water. This is exactly where the current study by the Jena researchers comes in.
The team found that the inconspicuous herb and moss layer of a forest acts as a powerful guardian. Sensors were installed at 93 measuring points in various forest types—from beech to spruce and pine forests. These sensors recorded which nutrients seeped through the top layer of soil over an entire year. The result is clear: where the forest floor is densely covered, significantly less nitrogen reaches the subsoil.
The Laboratory on the Doorstep: Research at the Saale-Elster-Platte
For their surveys, the scientists used the so-called Saale-Elster-Sandsteinplatte-Observatorium south of Jena. This region offers ideal conditions for comparing different forest types under real conditions. In the process, mosses emerged as particularly effective “nitrogen filters.” Unlike fast-growing herbaceous plants, which absorb nitrogen quickly but release it just as fast, mosses hold the nutrients in the system for longer. In this way, they prevent the substance from seeping away unused and potentially contaminating the drinking water.
This finding is particularly relevant for Thüringen, where the forest is not only a recreational space but also an important factor for water management. Although the influence of trees on nutrient cycles has already been well researched, the undergrowth was long considered a scientific peripheral area—unjustifiably so, as it now turns out.
New Impulses for Forestry
The study by the Universität Jena is more than just pure basic research; it provides concrete approaches for modern, sustainable forestry. The results suggest that in the future, greater attention should be paid to the preservation and promotion of soil vegetation when maintaining and managing forests.
“It is worth looking down more often,” is the conclusion from the university. When foresters specifically promote the growth of mosses and small plants, they strengthen the forest’s natural filtering effect. This could mean that future forest strategies must not only focus on timber yield or the choice of tree species but must view the ecosystem holistically from the ground to the crown.
For nature lovers in Jena, this means: on your next forest walk in the Mühltal or on the Forst, perhaps pause for a moment and consider the soft cushions of moss not just as decoration, but as diligent environmental protectors.