Overview of environmental themes and impact on nature in the Netherlands

Environmental theme	Impact on nature
Climate change - enhanced greenhouse effect	The global rise in temperatures as a result of the enhanced greenhouse effect influences the spread of plants and animals. Major consequences can be expected as a result of, in particular, the rising sea levels caused by the melting of polar ice and changes in precipitation patterns. The shift in the areas inhabited by plants and animals towards the poles is now becoming increasingly clear. In the Netherlands, the result has been the emergence of species from the south, as well as the possible disappearance of northern species. The plant and animal species that have moved to and settled in the Netherlands in the last century are mostly from the south. Hardly any, if at all, come from the north. Nevertheless, these phenomena cannot simply be explained by reference to the increase in global temperatures. Northern species that have disappeared from the Netherlands, or which are about to, are primarily victims of biotope destruction. Furthermore, a number of newcomers to the Netherlands are found almost exclusively in areas where humans predominate, such as urban and industrial areas and alongside roads. These 'built-up' areas have a warmer climate and therefore favour species that thrive in warm conditions. Nevertheless, there are all sorts of examples of increasing numbers of southern species outside urban areas, such as the wasp spider, the oak processionary caterpillar, the crimped gill fungus and lichens. The aquatic environment has also seen the emergence of species from the south such as the small hermit crab, the sea squirt and a few fish species. In addition to shifts in distribution, changes have also been observed in the times when plants grow and bloom and in bird breeding seasons. Relevant sections and indicators in the Environmental Data Compendium Guidance Climate change: consequences for flora and fauna Guidance Exotics Guidance urban area: bricking over
Eutrophication and acidification	Eutrophying and acidifying substances make the environment more nutrient-rich and more acid. The effects of these substances are difficult to separate because some of the acidifying substances also have a eutrophying effect. The increase in nutrient levels and acidity has a major impact on nature, especially on plant numbers. Indirect effects may also be apparent. For example, a lower concentration of eutrophying substances in the surface water of the lakes between the old coastline and reclaimed land influences the numbers of aquatic plants and, indirectly, of water fowl. Acidifying substances have a negative influence on mycorrhizal fungi. There has been some recovery in recent years. Lichens that are sensitive to sulphur dioxide have benefited considerably from the reduction in the levels of acidifying substances. Ammonia has had a local negative effect on lichens. Acidification and eutrophication, but also desiccation, have caused the decline in typical fen vegetation. Relevant sections and indicators in the Environmental Data Compendium Guidance Eutrophication and acidification: consequences for nature Guidance Heathland and fens: water draw down and acidification Guidance Heathland and fens: encroachment of grasses and trees Guidance Forest and woodland: water draw down and acidification Guidance Marshes, bogs and swamps: scrub encroachment
Spread of environmentally-hazardous substances	Human activities release substances into the environment which are not found there naturally or only in very low concentrations. Some of these substances, such as pesticides, heavy metals, PCBs, dioxins and fuel oil, are harmful for plants and animals. In recent decades, there have been various examples of hazardous substances having a adverse effect on nature. In the 1960s, numbers of birds of prey and sandwich terns declined as a result of poisoning with organochlorocompounds. Seabirds suffer from fuel oil, shellfish from anti-foulings and seals, until recently, from PCBs. A targeted approach to the air, water and soil contamination in question has led to the recovery of a number of species. Relevant sections and indicators in the Environmental Data Compendium Guidance Hazardous substances: influence on nature Seabirds and oil spills in the North Sea
Desiccation	Drinking-water extraction in the dunes has led to a sharp reduction in the area of dune slacks, and to the decline of some species such as the dark green fritillary. Treated river water is infiltrated to replenish the stocks of drinking water. Infiltration has led to an increase in reeded areas to the benefit of some species of birds. In other areas in the Netherlands as well, the authorities sometimes resort to bringing in polluted water from outside the area during severe droughts. This can lead to the eutrophication of groundwater and surface water. Desiccation leads indirectly to an increase in eutrophication in a number of cases. In peatland areas, desiccation results in the faster decomposition of organic material and therefore more nutrients in soil and water. The heaths are much dryer than they once were so that species numbers have declined in fens, and in wet and damp heathlands. Finally, a lot of damp and wet grassland has been lost due to desiccation, usually in combination with eutrophication. The small pearl-bordered fritillary, a type of butterfly, is very susceptible to this. Desiccation in higher-lying areas also affects surrounding biotopes in lower areas. For example, it can lead to less alkaline rainwater in lower areas, something on which a number of plant species depend. The current policy is aimed at the hydrological and ecological recovery of desiccated areas. As a result, rewetting has now resumed in many areas. Relevant sections and indicators in the Environmental Data Compendium Guidance Water draw down; consequences for nature Guidance Marshes, bogs and swamps: scrub encroachment Guidance Heathland and fens: water draw down and acidification Guidance Heathland and fens: encroachment of grasses and trees Heathland in Brabant is suffering from water draw-down
Fragmentation	One of the threats to the survival of plants and animals is the fragmentation of the suitable biotope. Fragmentation can have a considerable impact on species that depend on large uninterrupted areas and species with only limited migration options. Heathland and bogs in the Netherlands have become increasingly fragmented. In addition to the distribution over large and small areas, the distance between the areas and the obstacles between the areas also play a role. One of the obstacles for many species is the dense road network in the Netherlands, in combination with increasing traffic levels. Traffic also has a direct effect on animals, such as the badger, for example when cars collide with them. The aim of the policy is to reduce fragmentation. Important instruments are the establishment of the national ecological network (EHS) with uninterrupted areas and linkage zones and the construction of all sorts of animal passageways at roads. Relevant sections and indicators in the Environmental Data Compendium Guidance Creation and protection of nature areas Guidance Fragmentation: consequences for nature
Source: CBS.	CBS/EDC/July04/0329