Indicator forest and wood

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.

Assessment of the state
poor poor
Assessment of the trend
negative negative
Q75 - 75% quantile 2015: 25.50873 Q75 - 75% quantile 2010: 28.976295 Q75 - 75% quantile 2000: 31.13638 Q75 - 75% quantile 1990: 36.20135 Q75 - 75% quantile 1980: 41.8174975 Q75 - 75% quantile 1970: 35.84574 Q75 - 75% quantile 1960: 27.84512 Q75 - 75% quantile 1950: 22.2504825 Q75 - 75% quantile 1940: 21.7296575 Q75 - 75% quantile 1930: 19.293575 Q75 - 75% quantile 1920: 17.6256025 Q75 - 75% quantile 1910: 16.0837225 Q75 - 75% quantile 1900: 14.4774525 Q75 - 75% quantile 1890: 13.06299 Q75 - 75% quantile 1880: 12.0363375 Q25 - 25% quantile 2015: 13.75486 Q25 - 25% quantile 2010: 17.6145525 Q25 - 25% quantile 2000: 18.908835 Q25 - 25% quantile 1990: 22.84238 Q25 - 25% quantile 1980: 23.6180625 Q25 - 25% quantile 1970: 20.231 Q25 - 25% quantile 1960: 15.4141475 Q25 - 25% quantile 1950: 12.44703 Q25 - 25% quantile 1940: 12.43849 Q25 - 25% quantile 1930: 11.1948075 Q25 - 25% quantile 1920: 10.378915 Q25 - 25% quantile 1910: 9.601977 Q25 - 25% quantile 1900: 8.7354635 Q25 - 25% quantile 1890: 7.9713945 Q25 - 25% quantile 1880: 7.42897175 Mean value 2015: 20.4102661794035 Mean value 2010: 23.9051462221152 Mean value 2000: 25.4554579442306 Mean value 1990: 29.9596816284916 Mean value 1980: 33.3767080188789 Mean value 1970: 28.6315920299558 Mean value 1960: 22.23167501204 Mean value 1950: 17.8575895387208 Mean value 1940: 17.506049392121 Mean value 1930: 15.6421253507031 Mean value 1920: 14.3766633264304 Mean value 1910: 13.2079781012328 Mean value 1900: 11.9552272522635 Mean value 1890: 10.8382840384318 Mean value 1880: 10.0279366526681
Nitrogen input (N input) in Swiss forests. The limit values for forest ecosystems are 5-20 kg of N/ha/year.

Data for the graph: Excel
Source: NABEL; LFW; IAP
Comment

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 (NH3 from agriculture) have hardly changed. This is a direct result of emissions developments. Average nitrogen inputs in forests, which are 20.4 kg of N/(ha per year, 2015), are in excess of the critical loads for nitrogen. The exceedance of the critical loads in more than 95% of forests in Switzerland poses the potential threat of eutrophication and acidification.

International comparison

The method underlying the indicator is an international standard.

Method

Swiss-wide calculation by Meteotest, method described in: Rihm, B. and B. Achermann, 2016. Critical Loads of Nitrogen and their Exceedances. Swiss contribution to the effects-oriented work under the Convention on Long-Range Transboundary Air Pollution (UNECE). Federal Office for the Environment, Bern. Environmental studies no. 1642: 78 p.
https://www.bafu.admin.ch/bafu/en/home/topics/air/publications-studies/publications/Critical-Loads-of-Nitrogen-and-their-Exceedances.html

 

 
Last updated on: 17.05.2019

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