Nitrogen input in the forest
Nitrogen inputs are a serious burden on forests. Excessive nitrogen inputs result in imbalanced nutrition, root growth disruptions and nutrient absorption in trees. As a consequence, trees become more susceptible to diseases and pests. In the soil, excessive inputs cause acidification and nutrient leaching in addition to nitrate. This changes the quality of the soil over the long term. Eutrophication in forests generally occurs when there is an increase in nitrogen-loving plants such as elderberries and blackberries.
poor
negative
Forests continue to have high levels of nitrogen inputs. Since 2000, a decrease has been recorded only for oxidised nitrogen compounds, while inputs of reduced nitrogen compounds (ammonia from agriculture) have hardly changed. This is a direct result of emissions developments. Average nitrogen inputs in forests, which are 20.1 kg of N/ha per year (2020), are in excess of the critical loads for nitrogen. The exceedance of the critical loads in about 87% of forests in Switzerland (2020) poses the potential threat of eutrophication and acidification. Consequently, the state is judged to be poor. The trend evolution has been increasing since 1880 but has seen a decrease since the 2000s. On this basis, the trend evolution is judged to be negative.
- Related indicators
- Kronenverlichtung
- Waldbrände
The method underlying the indicator is an international standard. The Swiss data are calculated in a spatially very fine grid (500m x 500m) due to the small-scale strongly changing topography. Their quality can be classified as very good.
In European comparison, Switzerland is among the areas with high nitrogen inputs. This is primarily due to intensive livestock farming.
The swiss-wide calculation is carried out by Meteotest.The method is described in: Rihm und Künzle, 2023. Nitrogen deposition and exceedances of critical loads for nitrogen in Switzerland 1990–2020.
| Targeted trend | Initial value | Final value | Variation in % | Observed trend | Assessment |
|---|---|---|---|---|---|
| Decrease | 1880 | 2020 | (1) 129.88%, (2) 118.35%, (3) 131.30% | (1) Growth, (2) Growth, (3) Growth | negative |
| (1) Mean value, (2) Q25 - 25% quantile, (3) Q75 - 75% quantile | |||||
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