Biodiversity refers to the diversity of living organisms of any origin. It includes the diversity within species (genetic diversity), between species (species diversity) and the diversity of ecosystems (1).

Biodiversity in numbers

So far, 28,000 plant and fungi species have been found in Germany, among which are 3,242 flowering plants. Insects are, with 33,305 species, the largest group among the approximately 48,000 animal species occurring in Germany. There are 706 species of vertebrates in Germany, the species richest among which are teleost fishes and birds. With 91 species, mammals are only a small group among vertebrates (3).

The population of many of these species are currently under threat. Among monitored plants, 28.7% are threatened and 3.7% have already gone extinct. Among animals, e.g. 71% of amphibian and reptile species, 37% of bird species, and 38% of mammal species are threatened. Six percent of bird species and 13% of mammals have already gone extinct (4).

Among the approximately 500 types of biotopes over two thirds (69%) are ranked as threatened. On the other hand, for some species, especially birds, but also some bat species, a positive population development is observed. These are the effects of current protection schemes, such as the Guidelines for Fauna and Flora Habitats, which was implemented in 1992, and measures for extensification of agriculture. The coherent network of NATURA 2000 includes the areas registered under FFH and guidelines for bird protection, which cover approximately 13% of German land area (5).

Vulnerabilities - General

Wetlands, montane shrubs, and vegetation communities on rock or stone are particularly vulnerable. Regionally, the Alpine area is particularly impacted, because of its abundance of endemic plants and animals, many azonal biotopes and unique climatic locations (2).

There are a number of further factors that impact biodiversity and nature conservation negatively at present and in future, namely land use changes, such as e.g. disturbance, fragmentation and destruction of habitats through development, transport, agriculture and forestry, as well as replacement of native species by invasive species, some of which profit from climate change. Other negative impacts on ecosystems and biological diversity will be the increased expansion of pests through milder winters, more frequent forest fires (due to increased temperatures and aridity in summer), as well as extreme rainfall events, floods and droughts (2).

The assessment of the vulnerability of the nature conservation sector is difficult, because it depends to a large extent on the objectives of the protection of biodiversity. Vulnerability with and without further adaptation needs to be rated as “high” if the conservation of present level species richness is the goal. Even if changing species compositions are accepted, vulnerability without further adaptation will still be “moderate” to “high” (2).

The processes brought about by anthropogenic climate change will most probably exceed the adaptation potential of many biological systems and will therefore threaten the diversity and stability of species, habitats and ecosystems in general. A reduction of vulnerability to “moderate” levels should be possible if adaptation options are implemented through nature conservation management – this will in any case require special public and governmental support (2).

In the medium to long term, changes in species composition and communities in Germany cannot be avoided (2).

Species characteristics that indicate a high degree of vulnerability to climate changes include a low breeding rate, poor capacity to spread, low abundance, a small geographical range, limited ecological amplitude or a high degree of specialisation with regard to habitat and food requirements. Since these characteristics are typical of many species that are already endangered, there is reason to fear that species of importance from a nature conservation point of view will make up a disproportionately large share of the “losers” in the process of climate change (17).

Vulnerabilities - Terrestrial biodiversity

Climate change will affect terrestrial biodiversity in many ways, a.o. through a change of species diversity, through the adaptation of species to changes in the lenght of seasons, and through soil characteristics.

Changing species diversity

Changes in species composition, which are linked to climate change, have already been observed in Germany and Central Europe. Thermophilic animal and plant species, mostly sub-Mediterranean, Mediterranean, Atlantic, but also sub-tropical and tropical species immigrate or expand their limits of distribution towards north and east. … On average, a study of 99 species (birds, butterflies, Alpine plants) showed a shift in species distribution per decade of 6.1 km North or 6.1 m up in altitude respectively (4). For Norway spruce in the Northern Limestone Alps (Germany and Austria), however, neither growth suppression at the lower elevation sites nor growth increase at higher elevation sites was observed in a dataset covering more than 150 years (until 2003), despite a sharp temperature increase of ~1°C since the 1990s (20). According to the authors, these findings reveal the ability of mountain forests to adapt to an unprecedented temperature shift, suggesting that adaptation to forthcoming climate changes might not require a shift in tree species composition in the Northern Limestone Alps (20).

Model simulations project an extinction of 10-30% of present species owing to climate change in Central Europe (9). In Germany between 5-30% of the present animal and plant species could be affected (10,16). The “worst case” scenario shows a possible loss of species in Germany by the year 2080 ranging from 25% (northwestern Germany) to over 50% (southern and eastern Germany) per grid cell (11). When taking into account potentially new species, which immigrate from the south, leads to a different picture: The number of species per grid cell of herbaceous plants in Germany decreases by 4-14% by 2080, depending on the emission scenario.

Especially strong declines of up to 36% are found in the Alpine region and in southwestern Germany. Trees show little sensitivity up to the year 2050, but then exhibit a distinct increase in tree species diversity up to the year 2080 under most scenarios, particularly in northern Germany (2).

Amphibians and reptiles exhibit an increase in species richness per grid cell until 2050 by approximately 10%, followed by a decline to previous levels by 2080. The reason for this is that under a moderate increase in temperature current and new species from the south could co-exist. If temperature rises further, conditions for current species deteriorate rapidly (2).

Birds do not exhibit any considerable changes under this statistical analysis. However, we have to expect that changes in landscapes affecting resting and nesting places will nevertheless have a negative impact on populations (2).

Climate change can affect specific species within a community very differently. … This can lead to the decoupling of food webs and the break-up of symbiotic relations between species (2,16). It must therefore be expected, that old communities will be dissolved and new connections between species in different “climatic envelopes” will develop (2).

Seasonal shifts

Warmer spring temperatures and longer summers have lengthened the vegetation period of many tree species from Central Europe by on average 10 days since the 1950s (6). An analyses of data over the period 1961 – 2010 showed that the beginning of leaf unfolding of common horse chestnut and the date on which goose-berry fruits are ripe for picking have advanced 4.7 and 6.2 per degree K warming, respectively (21). The beginning of leaf colouring of common oak was delayed by 2.2 days per degree K warming (21). Milder winters are one of the main factors explaining why many birds have given up or altered (earlier arrival, later migration) their migratory behaviour (4).

Furthermore, continued changes in phenology in the form of elongated vegetation periods are expected (8). This can lead to an increase of yields for plants, but goes along with a higher susceptibility to late frost and infestation with pests. In general, further threats to species and extinctions due to climate change are expected in Southern and Central Europe.

Spring and summer phenological anomalies in Germany, such as leaf unfolding and flowering of different species, strongly correlate with temperature of the preceding months and their onsets have advanced by 2.5 to 6.7 days per °C warmer spring. Fruit ripening correlates well with summer temperature (shown for some species) and also advances by 6.5 and 3.8 days per °C (April–June). The length of the growing season is mainly increased by warmer springs and lengthened by 2.4 to 3.5 days/°C (February–April) (15).

Northward shift

Various scenarios project a further Northward shift of climate zones by the year 2100 by 200 to 1200 km (2004) and by several hundred meters up in altitude (7). This surpasses the maximum speed of migration (approximately 20 to 200 km per century) of many species. Moreover, migration is hindered by the lack of suitable habitats (2).

Soils

Climate influences many soil processes. It thus affects the development of soils, soil characteristics and soil functions. Climate and usage changes affect nutrient and water cycles and soil-formation processes (humus formation / carbon binding, groundwater formation, soil degration via erosion, nutrient cycles / growth conditions). Consequently, such changes can affect key natural soil functions and, in some cases, can impair them (16).

Vulnerabilities - Fresh water and wetlands biodiversity

In the medium- to long-term, wetlands and moors are also particularly impacted through decreasing precipitation and more evaporation in summers, and changes in flooding patterns. The consequence is increasing annual amplitudes of the groundwater levels, but particularly deeper groundwater levels in dry summer months, which will be more frequent in future (16,19).

Warming of lakes and rivers causes their oxygen concentration to fall. This means stress for the fauna and flora living in them – in addition to the already low water level. higher temperatures also make for easier separation of pollutants previously attached to sediments (18).

Vulnerabilities - River water temperature

Water temperature of the River Rhine is rising. It has been rising by over 2 °C in summer (near Koblenz) between 1978 and 2011 (22), an effect caused by an increase in annual mean air temperature and thermal discharges. Water temperature will continue to rise as a response to projected climate change.

An ensemble of (global and regional) climate models was used to produce a plausible range of projections for future water temperature in the Rhine. These projections are based on an intermediate scenario of climate change (the so-called SRES A1B scenario) for the near future (2021-2050) and far future (2071-2100). Future projections were compared with the period 1961-1990 (reference) (23).

With respect to 1961-1990 mean annual water temperature of the Rhine will rise due to climate change between +0.6 and +1.4 °C in the near future, and between +1.9 and +2.2 °C in the far future. Increase is highest in summer and lowest in spring. At the end of this century projected temperature rise is +2.7 to +3.4 °C in late summer and +0.4 to +1.3 °C in spring (23).

The maximum number of successive days with a water temperature above 27 °C increases from 4 days in the reference period (at Koblenz) to 10 days in the near future, and 17 days in the far future. These prolonged durations of periods with unusually high water temperatures may provoke changes in the food web and in the rates of biological processes in the Rhine (23).

Measures or new regulations regarding the thermal load plan for the Rhine may be needed in the future since the maximal allowed water temperature of the Rhine downstream of thermal discharges is currently 28 °C (24), and the impact of thermal pollution should be added to the climate change effect above. Currently, several power plants and industrial facilities lead their thermal discharges into the Rhine, leading to water temperature increases up to 1.4 °C (22). Higher water temperatures may negatively affect river ecology (25).

Vulnerabilities - Marine, estuarine and intertidal biodiversity

The Wadden Sea (Wattenmeer), an especially sensitive ecosystem, could be especially at risk if it loses habitats to permanent flooding and to erosion. Species with little ability to extend their ranges will also face increasing risks (16).

Baltic Sea

The Baltic Sea today suffers from eutrophication and from dead bottom zones due to (26)

1. excessive nutrient loads from land,
2. limited water exchange with the world ocean and
3. perhaps other drivers like global warming.

The impact of excessive nutrient loads is the most important driver. Without elevated nutrient concentrations, hypoxia would not have occurred during the twentieth and twenty-first centuries (29).

Model simulations (26) suggest that global sea level rise will cause increases in

1. frequency and magnitude of saltwater inflows,
2. salinity and phosphate concentrations in the Baltic Sea as a direct or indirect consequence of increased cross sections in the Danish straits, and will contribute to
3. increased hypoxia and anoxia amplifying the previously reported future impacts of increased external nutrient loads due to increased runoff, reduced oxygen flux from the atmosphere to the ocean and intensified internal nutrient cycling due to increased water temperatures in future climate (27).

Although sea level rise will cause more intense inflows of high saline, oxygen-rich water, hypoxic bottom areas will increase because of increased stratification (26).

The combined impact of changing nutrient loads from land and changing climate during the 21st century for the Baltic Sea region has been assessed, for a moderate (RCP 4.5) and high-end scenario (RCP 8.5) of climate change (28). The scientists found in almost all scenario simulations, with differing nutrient inputs, reduced eutrophication and improved ecological state compared to the reference period 1976-2005. This result is a long-lasting consequence of ongoing nutrient load reductions since the 1980s. Only in case of combined high-end nutrient load and climate scenarios, eutrophication is reinforced. Effects of changing climate, within the range of considered greenhouse gas emission scenarios, are smaller than effects of considered nutrient load changes, in particular under low nutrient conditions. Hence, nutrient load reductions following the Baltic Sea Action Plan will lead to improved environmental conditions independently of future climate change (28). 

Vulnerabilities - Alpine biodiversity

Ecosystems of the Alps are particularly impacted (12,14). In the Alps, relief, soil and climate vary greatly and on a small scale, supporting a mosaic of highly diverse habitats and biotopes. The Alps are home to approximately 30,000 animal and 13,000 plant species, approximately 39% of the European angiosperm flora. About 15% of the 2,500 plants growing above the tree line are endemic (12).

Alpine plants are particularly sensitive to climate change, owing to their narrow ecological tolerance and the lack of migration options (alternative habitats are lacking). Additionally, species migrating from lower areas will increase the pressure. Such species may increase species diversity of Alpine regions in the short-term, but will lead to extinctions of endemic species in the long-term (13).

Adaptation strategies

Adaptation measures should primarily seek to maintain and promote natural adaptive potential. This includes measures to enable migration (e.g. connecting habitats) and flexible concepts of protection. Wetlands require special protection (e.g. through alterations in water management) (2).

As part of the European coordination of nature conservation efforts (e.g. NATURA 2000) and additional national initiatives, many of these adaptation measures have already been introduced and some have already been fully implemented. However, only in a few cases this is in direct response to climate change. Therefore, monitoring of climate change impacts on biodiversity and climate change related trends should receive more attention in nature conservation in future (2).

Connection of biotopes

Of special importance is the maintenance and improvement of migration options for species. These include measures to connect biotopes on local, regional, national and transnational scales. This task has been adopted in the new version of the Federal Nature Conservation Act, which states that the federal states should dedicate at least 10% of their land area to the connection of biotopes.

Wherever possible, development of such biotope networks should be taken into account in refinement of agricultural-sector environmental measures, and other relevant measures, in the context of the second pillar of the EU's Common Agricultural Policy and in the framework of a national programme for riparian meadows (Nationales Auenprogramm). Fragmentation of natural systems and land consumption need to be reduced (16).

The Natura 2000 network already offers suitable refuges and adaptation areas, both on land and in the sea, as well as areas that remain free of uses. It thus contributes to efforts to mitigate the negative impacts of climate change (16).

To adapt to climate change, dynamics of natural processes are very important. Besides migration they include also e.g. succession, rejuvenation or fires (2).

Water management

Water management concepts show the highest degree of implementation compared to other measures used in the nature conservation sector in Germany. For those involved, the impacts of climate change were not among the reasons to implement these measures in any federal state (2).

For wetlands, like in the Elbe Lowland,different water management options such as the improvement of the water storage in the wetlands or water transfer from neighbouring river basins are in discussion to lower the impact of global change. However, in most of the lowland catchments, the alternatives are limited. Saving surplus water in the winter will be the only option to reduce water shortage problems in dry periods (19).

Soils

Climate-related changes in soil systems have direct impacts on natural production systems, on water cycles (both qualitatively and quantitatively) and on biological diversity. At the same time, proper precautionary measures help reduce and prevent soil erosion, and adverse soil compression, and they help protect organic substances in the soil, thereby protecting the soil's ecological vitality. Such measures are thus suitable measures for adaptation to climate change (16).

Policy

Marine conservation must be based on a holistic ecosystemic approach. Such an approach calls for integration of all policy areas that can affect the quality of the marine environment, especially its biological diversity. The European marine conservation strategy, including the Marine Strategy Framework Directive, is a significant example of such integration. That effort is being complemented, and specially outlined for Germany, by a National Marine Strategy (16).

The Federal Government and the Länder will need to take suitable measures to ensure achievement of the quantitatively and qualitatively defined objectives, for protected areas and conservation networks, set forth in the National Biological Diversity Strategy and in the Federal Nature Conservation Act (16).

Efforts should be made, via use and improvement of suitable management systems, to enhance synergies between agricultural production, nature conservation, soil conservation, protection of water bodies and climate protection (16).

Invasive species

States sharing common borders should establish suitable early-warning systems, with respect to species groups that have not yet received sufficient attention in this regard. Wherever possible, biotope networks should be designed in ways that do not encourage the spread of invasive species.

Further measures

Moreover, further measures that may be suitable to prevent risks of climate change or capitalize on opportunities in Germany are: NATURA 2000, Life Projects, federal nature protection projects, conversion of pine to deciduous forests, sustainable and nature-oriented land use (e.g. reduced usage of pesticides and fertilisers), extensification of agriculture, measures of renaturalisation and nature-oriented management, nature conservation oriented land use and contracted nature conservation (2).

References

The references below are cited in full in a separate map 'References'. Please click here if you are looking for the full references for Germany.

1. Convention on Biological Diversity (1992), in: Zebisch et al. (2005)
2. Zebisch et al. (2005)
3. Völkl (2004), in: Zebisch et al. (2005)
4. BFN (2004), in: Zebisch et al. (2005)
5. BFN (2005), in: Zebisch et al. (2005)
6. Menzel (1997), in: Zebisch et al. (2005)
7. Hughes (2000), in: Zebisch et al. (2005)
8. SCBD (2003), in: Zebisch et al. (2005)
9. Bakkenes et al. (2002); Thomas et al. (2004), both in: Zebisch et al. (2005)
10. Leuschner and Schipka (2004), in: Zebisch et al. (2005)
11. Schröter et al. (2004, 2005), in: Zebisch et al. (2005)
12. Grabherr (1998), in: Zebisch et al. (2005)
13. EEA (2004), in: Zebisch et al. (2005)
14. Swart et al. (2009)
15. Menzel (2003)
16. Government of the Federal Republic of Germany (2010)
17. Government of the Federal Republic of Germany (2006)
18. Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (2009)
19. Dietrich et al. (2012)
20. Hartl-Meier et al. (2014)
21. Wittich and Liedtke (2015)
22. ICPR (2013a), in: Hardenbicker et al. (2017)
23. Hardenbicker et al. (2017), in: Hardenbicker et al. (2017)
24. LAWA-AO (2007), in: Hardenbicker et al. (2017)
25. Hilton et al. (2006), in: Hardenbicker et al. (2017)
26. Meier et al. (2017)
27. Meier et al. (2011), in: Meier et al. (2017)
28. Saraiva et al. (2019)
29. Meier et al. (2019)