At a glance
- 54 % of vulnerable ecosystems in Germany are threatened by excess nitrogen deposition.
- As part of the revised German Sustainable Development Strategy, the Federal Government aims to reduce this to 37 % by 2030.
- This target is feasible only if efforts to reduce air pollution are maintained.
The maximum amount of pollutants that ecosystems can tolerate without being damaged is known as the ‘critical load’. It is a measure of an ecosystem's sensitivity to pollution. Air pollution levels above these critical loads can permanently damage ecosystem structures and functions.
Excess deposition of airborne nitrogen compounds in terrestrial ecosystems can cause nutrient imbalances which may modify the species composition. Organisms that prefer low-nitrogen conditions will be displaced in favour of species that thrive in nitrogen-rich habitats.
Almost half of ferns and flowering plants on Germany’s Red List are threatened by nutrient deposition. Moreover, many plants become more susceptible to frost, drought and pests due to changes in nutrient availability. The indicator focuses on natural ecosystems, especially forests, inland marshes, peat bogs, heathlands and nutrient-poor grasslands.
Assessing the development
Despite declining nitrogen deposition, in 2010 critical loads were still exceeded in 54 % of the area comprising vulnerable ecosystems. In 1980 this figure was as high as 82 %. High ammonia emissions associated with livestock farming and fertilisation are particularly problematic. These have fallen only marginally and are not expected to decline steeply in the near term.
The National Strategy on Biological Diversity includes the target of not exceeding the critical loads by 2020 (BMU 2007). This target is no longer feasible, but in the German Environment Agency's view it should remain a long-term goal. The Federal Government has set a new target in the German Sustainable Development Strategy 2016: The proportion of land affected by excess nitrogen deposition should fall by 35 % between 2005 and 2030 (Federal Government 2016). With the current basis for calculation, this gives a target value of 37 % in 2030.
The German Environment Agency proposes measures aimed at solving the problem of nitrogen eutrophication in its publication ‘Reactive nitrogen in Germany’ (UBA 2015).
The first stage is to calculate critical loads for vulnerable ecosystem types: How much nitrogen can be deposited without damaging the ecosystem in the long term? The critical loads are compared with substance depositions in the ecosystems, calculated in accordance with the Geneva Convention on Long-range Transboundary Air Pollution. More information is available in European Environment Agency (EEA) and German Environment Agency reports (EEA 2014, UBA 2014 in German only). The German Environment Agency is currently working on a consistent national time series for the indicator as part of a research project.
Associated with the reporting of the National Strategy for Biodiversity a related indicator is published (BMUB 2015). Due to deviating methods this indicator shows other values.
More detailed information: 'Überschreitung der Belastungsgrenzen für Eutrophierung' (in German only).