Biodiversity in numbers

The Netherlands contains 51 natural habitat types (1), a relatively high amount if we consider that it represents almost a quarter of all habitat types listed in Europe. The Netherlands contains important areas of salt meadows, coastal dunes, dry sand heath on inland dunes, natural eutrophic lakes and raised bogs. It provides habitat to 28 species of wild plants and animals, mentioned in the Annexes of the EU Habitat Directive (92/43/ECC), and to about 100 species of birds, mentioned in the Annexes of the EU Birds Directive (79/409/ECC) (2).

The Wadden Sea ecosystem, along the coast of the Netherlands, Germany and Denmark is a ‘Wetland of International Importance’ according to the Convention of Ramsar (1975) and has been recognized as a Biosphere Reserve by UNESCO (1990). Dutch wetlands and grasslands are of great international importance for water birds, partly because the Netherlands is located at the junction of flyways between the Arctic tundra and the African continent (2).

Vulnerabilities - Terrestrial biodiversity

The rate at which the temperature rises is likely too high to enable many species to adapt or migrate. Several plant and animal species are threatened with extinction in the Netherlands. New species will settle if they can migrate quickly enough. This will probably lead to a decreased diversity of species in the Netherlands (12).

The most relevant response of Dutch flora to the change in climate is a marked and quick increase of thermophile (warmth-loving) plant species as recorded from 1980 to 2000. A major concern is the threat posed by invasive species to indigenous species (3).

If the phenology of the various species is shifting at a different rate this may lead to mis-timing of seasonal activities. … The more restricted the preferences in the food chain, the higher is the chance that species will not survive.

Seasonal shifts

Climate has an impact on phenological processes like the date of flowering, leaf unfolding, leaf fall, ripening of fruits or species migration. … several phonological changes are currently taking place in the Netherlands as a response to climate change. In 2004, the timing of life cycle events in plants was about 16 days earlier than the timing observed during the period 1868-1968. The start of the pollen season in the Netherlands has advanced, between 1969 and 2000, from 3 to 22 days. Moreover most of the butterflies appeared early in the last few years. The above changes are likely to be attributed to a rise in temperature (10).

From a long-term dataset (1868-2010) of phenological observations of 320 plant species it was concluded that until the beginning of the 1990s, there have been no significant changes in the timing of plant life cycle events in the Netherlands (19). During 2001-2010 the timing of flowering, leaf unfolding and fruit ripening has advanced on average by 13 days compared with 1940–1968. Some species have advanced up to over 35 days. Autumn events occurred up to an average of 7 days later in 2001-2010 compared to 1940–1968 (19).

These seasonal shifts may lead to mismatches across trophic levels. For the Netherlands, it was demonstrated that earlier bud break in sessile oak due to climate warming leads to an earlier appearance of caterpillars, thus disrupting food supply during the main hatching period of the migratory pied flycatcher, which did not keep pace in its arrival at breeding grounds with the advance in peak food supply. As a consequence of this mismatch in timing, pied flycatcher populations breeding in oak forest declined by 90 % between 1987 and 2003 (21).

Northward shift

To cope with climatic changes, species are expected to shift from southwest to northeast Europe, as has already been observed for several plant, animal and lichen species, with high reproducing and/or dispersal capabilities (11). However species with much lower adaptation capabilities are at risk, for example some butterflies of peat moors that are not very mobile, and moor frogs who may not tolerate rising water temperature.

In the Netherlands the acreage of plant species that prefer warm conditions has increased while that of species that prefer cold conditions has decreased. … If we look at the area distribution, both southern and northern species of breeding birds are losing ground in the Netherlands, whereas central European and indifferent species are gaining ground (12). Climate change has significant impacts on the winter distribution of migratory birds that fly south to avoid the northern winter: based on ringing data from the Netherlands, 12 of 24 species studied showed a significant reduction in their migration distance to the south, and this was strongly correlated with the Dutch winter temperature in the year of recovery (20). 

If the temperature rises by 2°C compare to the temperature around 1900, millions of geese in the Northern Hemisphere will lose 50% of their breeding ground and more than 30% of plants from more than 40% of Europe will disappear. Indigenous and specialized species may become extinct. It is estimated that the Benelux countries will remain a suitable habitat for about 90% of the current plant species and will become suitable for about 5-15% new species. Newly arrived species will only be able to settle in the Netherlands if there are suitable locations of the necessary size and quality, and if barriers do not hinder their migration (12).

Few ecosystems can adjust to a rise of 3°C or more. More than 20% of the ecosystems worldwide will then completely change, and more than 20% of all marsh areas will be lost. It is not just the absolute temperature rise, the rate of this rise is also of particular importance. A rate of 0.1°C per 10 years is considered by many experts to be a threshold value. In such a situation, 50% of the current ecosystems are still capable of coping with the changes. Above this threshold level, ecosystems will become damaged (12).

In the Netherlands, the temperature has risen by almost 1°C over the past 30 years –  in other words, close to 0.3°C per 10 years. This rate is so high that non-mobile plants and animals cannot keep pace with it. Moreover, as the Netherlands is densely populated and urbanized, plants and animals continually face man-made barriers and therefore cannot always shift their habitat. Species need to shift by 4 km per year to keep pace with the current temperature rise. This is equivalent to about 10 m per day over the entire year irrespective of the season (12).

Changes in occurrence of pests and diseases

Changes in temperature and humidity are expected to promote pests and diseases in the Netherlands (4).

Indirect impacts

The flexibility and resilience of systems like peat moors, wet heathlands and grassland is reduced under drought condition. … Drought is currently affecting 50% of deciduous forests, especially deciduous forests on sandy soils in the southern and eastern parts of the Netherlands are sensitive to lack of water. Some trees, like Beech and Birch suffer very much from drought whereas Oaks have difficulties to adapt to changing water tables (5).

Land subsidence in the peat areas will probably increase. Depending on the waterlevel, this land subsidence can be up to 1 cm per year. At this rate, a subsidence of 0.5 m will occur in some of the peat areas until 2050 … The rising temperature, the longer summer season and a greater difference between wet and dry conditions will most likely result in a faster oxidation of peat. This in turn may lead to accelerated subsidence. … Various provinces, especially in the western part of the Netherlands, have consequently included measures to counteract land subsidence. These measures, however, only affect 4% of the total peatland area (12).

Groundwater tables are expected to become more complex to manage due to the more extreme shifts between summer and winter temperature and precipitation patterns. Nature areas that already suffer from lowered groundwater tables, because of surrounding agricultural practices and resulting lack of buffer capacity, are vulnerable to droughts. These affected nature areas are common in the Netherlands (12).

In the summer more surface water will have to be discharged into the fenlands to maintain a high water level. The relatively low quality of this water may result in a deterioration of the biodiversity of the fenlands (16).

Extreme events like fire and storms can cause damages to the ecosystem composition of forests and it is very likely that species will have problems to recover because of landscape fragmentation in the Netherlands (5).

Vulnerabilities - Fresh water and wetlands biodiversity

The water temperature in the shallow lakes of the Netherlands is gradually increasing … A sudden rise seems to have taken place between 1987 and 1990; this rise is parallel to the outdoor air temperature and probably associated with a rise in the NAO index (12)

The influence of water temperature and other climate effects on (swimming) water quality is on balance much smaller than the influence of nutrients and the composition of the fish stock. For example, lakes with a high phosphorus load are always turbid and mostly experience problems from blue algae, whereas those with low phosphorus loads are always clear and do not, or scarcely ever, experience problems from blue algae. The net result is that climate effects are often difficult to distinguish from other effects.

The rising temperature will probably facilitate blooms of blue algae and botulism in Dutch lakes, thereby leading to a higher chance of mortality among waterfowl. Increasing peaks in rainfall will increase the leaching of phosphorus from the soil into surface water and, consequently, loading of lakes. More phosphorus means a higher chance of algal blooms, as a result of which lakes may become even more turbid. Turbid lakes have a lower biodiversity than those with clear water (12).

The risk of eutrophication, algae blooms and low oxygen levels in fresh water systems will increase in warmer and drier summers due to the longer residence time of water in rivers, lakes and canals (17).

A temperature rise of 2–5°C may lead to an increase in the species diversity in streams. However, when bodies of water will dry up, the number of species would drastically decrease (12).

Vulnerabilities - Marine, estuarine and intertidal biodiversity

In a large part of the North Sea the quantity of phytoplankton is decreasing as the temperature of the seawater rises. In addition, the peak of the spring bloom is occurring increasingly earlier. However, the peak density of zooplankton feeding on phytoplankton occurs later in the season, when the availability of phytoplankton as a food source has already dropped. The peak in the plankton bloom is also no longer synchronized with the larval stage of fish and, therefore, fewer fish reach maturity. This means that a limited amount of food is available for the higher levels in the food chain (12).

While overfishing in the North Sea is directly affecting fish populations in general, the rising temperature is probably at least in part responsible for the poor state of the cod population. Fewer larvae are surviving than in the past. This decrease in cod numbers has been attributed to both changes in the plankton and the direct effect of the water temperature on the physiology of the cod. However, there are indications that at the end of the 19th century equally large shifts in the fish populations of the North Sea have occurred, in the absence of anthropogenic climate change effects. Therefore, natural variations and other human influences probably play a considerable role as well (12).

In the 1960s porpoises were rare along the Dutch coast. Since the 1980s they have been increasingly sighted, and in the past 15 years their numbers have increased by more than 40% per year. It is highly likely that this is due to a geographical shift in their distribution and not to an increase in the local population. This habitat shift of the porpoise is possibly correlated (fifty-fifty probability) with a local decrease or geographical shift in its prey in the northern North Sea, as a result of which the porpoise has moved further south looking for food. In turn, this change in prey abundance is probably an indirect consequence of the warming up of the seawater and the effects of this on the basis of the food chain (12).

With rising temperatures in the Wadden Sea, the expectation is that the reproductive capacity of shellfish will further decrease in the near future, with the result that shellfish-eating birds, such as Red Knots, oystercatchers and eider ducks, will find less food (12).

Moreover, if a sea level rise of more than 60 cm occurs in the second half of this century, the shellfish eaters might be doubly affected. The rate at which the sea level rises is more important than the absolute rise in sea level. If this rate rises above a critical value, the sedimentation might no longer keep pace, and sandbanks and salt marshes will become submerged. It is estimated that this critical boundary is between 3 and 6 mm per year. If sandbanks and salt marshes disappear, then many of the plants and animals that are dependent on these (such as shellfish-eating birds) will also disappear. Other factors such as eutrophication and fishing also play a role. The temperature might also influence the availability of nutrients (12,13).

Adaptation strategies

Several adaptation strategies help in preserving biodiversity. Corridors can be created that allow plants and animals to migrate. Areas can be protected and ecosystems can be restored. Plants and animals can be translocated from threathened areas to areas with climate conditions that better suit the species involved. Agro-environmental measures can be stimulated to protect wildlife and habitats and increase the environmental quality of agricultural land. Integrated water and coastal management serve biodiversity in many ways.

Corridors

The National Ecological Network (NEN), introduced in 1990 by the Nature Policy Plan, has been designed with the main purpose of restoring natural ecosystems lost during the past years as a consequence of human actions. Although the NEN was not originally meant as a climate adaptation measure, the creation of the NEN can enhance the adaptation capacity of species to climate change (2).

It is very important to improve existing corridors between green areas, and establish new ones, to allow plants and animals, especially those with low migration capabilities, to follow favorable environmental circumstances. Particular attention should be given to lowland forest and marsh ecosystems that are high fragmented (6). New corridors can be created through rehabilitation of degraded areas or conversion of areas which were used for other purposes (e.g. agriculture).

Biodiversity levels can be maintained in the face of climate change if nature conservation policies focus more forcefully than at present on increasing the spatial connectivity of nature conservation areas, improving environmental and water conditions, and creating room for natural processes.  For the internationally important habitats in the low-lying areas of the Netherlands, this will involve strengthening spatial connectivity in the coastal dunes, the peat marshes and the Rhine-Meuse floodplain, and restoring natural processes in the Wadden Sea, the south-west delta area and the coastal zone. Greater spatial connectivity and restoration of the natural hydrological dynamics is also required in forest and heathland ecosystems. Climate-proofing ecosystems and biodiversity, therefore will require revision of the government strategy for the National Ecological Network (18).

Policy plans could focus on safeguarding from development those areas that could be required for wildlife in the future, or promoting wildlife-friendly environments in both rural and urban locations for threatened species to move into or through (2).

In order to increase the robustness of the NEN, actions are required at a broader, international level (5). Currently some initiatives (e.g. the Pan-European Ecological Network (PEEN)) have been taken in order to establish a wide network of ecological areas within Europe. …. According to Sijtsma and Strijker (1995) the NEN leads to a biodiversity increase of 15 to 20% compared to the situation without this network.

Policy

Increasing the adaptive capacity of nature, given current nature policy, calls for a transition from a focused conservation (biodiversity, target species) to a more development-oriented policy (the functioning of ecosystems, the creation of conditions) and/or more dynamic target species policy (updating the species every few years) (8,15). Topics will mainly be peat and swamp nature, the sensitive nature types on the higher sandy soils, surface freshwater (which are sensitive to temperature rise and eutrophication), the southwestern delta and the Wadden Sea (8).

Protected Areas

The selection of sites should focus on areas which have the highest potential to provide suitable habitats to threatened species under changing climatic conditions. These areas can contribute to the expansion and robustness of the NEN, and can assure long-term protection of species and maintain biodiversity, not only within the Netherlands but in connection with other European countries (5).

In order to increase the robustness of ecosystems, it is also necessary to adjust management strategies for protected areas, e.g. to ensure certain environmental conditions, take into account pest-control measures or adjust water management (2).

Artificial translocation of plants and animals

Recently some researchers showed concerns about the efficiency of the ecological corridors and protected areas networks in supporting adaptation of species to climate change (7). … The results of this study lead the authors to propose artificial translocation of plants and animals as a way of preserving species under climate change. For example, for the conservation of many mammals, artificial translocation may be more useful than the creation of large-scale migration corridors; whereas wind-dispersed plants may be best conserved in disjunctive reserves aligned in the direction of projected climate change (2).

Implementation of effective agri-environmental measures

Agri-environmental schemes are implemented within the European Union since 1992. Farmers are paid to modify their farming practice in order to protect wildlife and habitats and increase the environmental quality of their agricultural land by reducing the nutrient and pesticides emission. Although not meant as an adaptation strategy to climate change, agri-environmental schemes could contribute in maintaining a variety of valuable semi-natural habitats, maintaining or increasing species richness and thus enhancing the resilience of the natural system against climate change (2).

Integrated water management for ecosystems

If well planned, integrated water management can provide benefits in many ways. It can increase the space available for species, create opportunities for the development of new nature areas and contribute to the expansion of the ecological corridors enabling thus migration of species. Indirectly, integrated water management can help in counteracting flooding and drought and thus can prevent damages to the ecosystem. Moreover it can enhance recreation (2).

In the Netherlands a program is being carried out to increase the discharge capacity for the Rhine and at the same time improve the conditions for nature development in the river floodplain.

For the low-lying Netherlands there are important synergies between climate adaptation and nature in developing river nature landscapes, adjusting the water management in the reclaimed land (polders) and peatlands, and in developing peat nature. In the high-lying Netherlands, there are opportunities for synergy in the development and restoration of brook valley systems and seepage zones (9).

Adjustments in water management may help making the fenlands and peat bogs less vulnerable to changes in (the quality of) the water balance (16).

Integrated coastal management

Sea level rise and flooding are main threats in the coastal areas, especially in low-lying areas. The following adaptation strategies can be considered (2):

• Re-establishment of the natural dynamics of the dunes. This can create opportunities for nature development and can reduce the risk of flooding, thus can prevent damages to the ecosystems;
• Use of natural areas (e.g. peatlands). These natural areas, besides enhancing the natural functions of the coastline, can increase the water retention capacity of the coastal zone, reduce the risk of salt water intrusion caused by sea level rise and prevent damage to the natural system;
• Wadden Sea: Enhancement and maintenance of salt marshes, Development of mussel beds and sea grass fields. Besides helping to safeguard, on a local scale, inter tidal areas from drowning, this measure can provide favorable conditions for other species and is therefore enhancing biodiversity.

Climate Buffers

Climate Buffers will, to a considerable extent, contribute to climate-proofing the Netherlands as they are able to grow with the pace of climate change (9). This means that all damage and threats (ecological, economic, hydrological) due to climate change can be reduced or offset through specific planning, and constructing buffer zones on critical sites. Climate Buffers serve to reduce the risk of flooding (and other water problems), while simultaneously reducing the effects of prolonged drought (both agriculture and nature). Climate Buffers can also be arranged so that they create secondary positive effects for living, landscape, cultural-history and recreation. Examples of climate buffers are (8):

• ‘Room for the river’ measures such as restoration of meandering patterns and deepening of the floodplains;
• Restoration of the, often channelled, streams in the upstream areas of the rivers to their natural meandering pattern. Thus, the sands and the hills in the upstream areas will hold water from (extreme) precipitation for a longer period and discharge (in lower areas) is more gradual. Besides, the sandy soils, in particular, will have less burden of dehydration during heat-waves;
• Increase and broadening of (narrow) dunes to make them more resilient and more defensible;
• Restore (and further promote) the natural sedimentation of flats, meadows, silts and salt marshes in the tidal landscape of the Wadden Sea and Zeeland, so they can keep pace with sea level rise (and subsidence);
• Raising groundwater levels in the fenlands so the continued subsidence will be slowed down or stopped completely.

Restoration of ecosystems directly depending on water quantity or quality

Though not explicitly designed as an adaptation strategy for coping with climate change impacts, the Water Framework Directive does explicitly state that it: ‘contributes to mitigating the effects of floods and droughts’. …  the WFD may be considered to be one of the means to enhance resilience of nature against any change, including impacts of climate change (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 the Netherlands.

1. NMP (2003), in: Nillesen and Van Ierland (2006)
2. Nillesen and Van Ierland (2006)
3. Tamis (2005), in: Nillesen and Van Ierland (2006)
4. Mooij et al. (2005), in: Nillesen and Van Ierland (2006)
5. Van Ierland et al. (2001), in: Nillesen and Van Ierland (2006)
6. MNP (2004), in: Nillesen and Van Ierland (2006)
7. Paerson and Dawson (2005),in: Nillesen and Van Ierland (2006)
8. Ministry of Housing, Spatial Planning and the Environment (2009)
9. Netherlands Environmental Assessment Agency (PBL) (2008)
10. Leemans and Van Vliet (2004), in: Nillesen and Van Ierland (2006)
11. Van Oene et al. (1999), in: Nillesen and Van Ierland (2006)
12. Bresser (2006)
13. Van Geijn (1998), in: Nillesen and Van Ierland (2006)
14. Mooij et al. (2005), in: Nillesen and Van Ierland (2006)
15. Raad voor Verkeer en Waterstaat (2009)
16. Interprovinciaal Overleg (2009)
17. Netherlands Environmental Assessment Agency (PBL) (2008)
18. PBL Netherlands Environmental Assessment Agency (2011)
19. Van Vliet et al. (2014)
20. Visser et al. (2009), in: Hölzel et al. (2016)
21. Both et al. (2006), in: Hölzel et al. (2016)