In consultations that included environmentalist groups, the HSL Project Organization will replace a total of around 200 hectares of natural area. The new natural areas will be laid out as close to the original areas as possible under competent management, for instance the Dutch Forestry Commission or Brabant Landscape. For each location an on-site assessment will be made to decide what is the best way to regain the nature.

It concerns the following areas in South Holland:

• lake area Oude Ade
• Achthoven Polder
• Groenendijk Polder
• Munniker Polder
• recreation area IJsselmonde
• Devel
• Oude Maas
• Marshlands Hollandsche Biesbos          

and the following areas in North Brabant:

• Weimeren
• Rooskensdonk
• Aa or Weerijs
• Breedbroeken            

The aim is to cause the least possible adverse consequences for all wildlife during the construction of the HSL, by taking extra care of nature and the landscape. Any adverse effects will be compensated or mitigated, for instance by connecting natural areas that are separated by the line.

On a large part of the route, the embankments, verges and ditches will be zoned as a so-called green ribbon, which means a wildlife area for plants and animals. To keep animal habitats as accessible as possible and their trusted migratory courses clear, passageways such as small tunnels, culverts and grids will be installed. These allow the animals to get safely from one side of the track to the other.   

If nature has to disappear (even a single tree), this will be compensated by creating new wildlife areas or planting a tree elsewhere. This compensation obligation has been laid down in the Green Spaces Structural Action Plan (SGR).

From Schiphol to the Belgian border, as many ditches as possible are conserved ecologically, and in places where the HSL crosses existing natural areas, ditches are continued under the line. In addition, new ecological zones are laid out.

A good example is the Hoeksche Waard area, south of Rotterdam. In this polder area, the banks of a number of coves are reorganised. As a result, more plants and animals are able to live here than before.

Another example is the Green Heart Area. The bored tunnel under the Green Heart has five aboveground tunnel buildings, and around these buildings ecological bogs are created. These bogs are to become a single ecosystem, serving as a connection between two existing natural areas.

A final example is the Ade Area north of Leiden, where environmental loss is compensated by means of agricultural nature conversation. Here the land remains the property of the farmer, who organises, manages and uses the land ecologically, collecting a subsidy granted for this purpose by the HSL Project Organisation.

All parties involved confer to arrive at the best solution for the environment. Ecologists and landscape architects are working closely together with such groups as environmentalists, conservationalists and the municipalities. The farmers living and working along the route are also an important link. In places where loss of nature is compensated by means of agricultural nature conversation, farmers who want to co-operate are eligible for a subsidy from the project organization, specifically intended for environmentally friendly farmers. In general, the various parties are working together well, in particular because now it is definitely known where and how exactly the HSL construction is taking place.

The 1993 Green Spaces Structural Action Plan (SGR) protects natural areas, forests and recreation areas in those areas that have been granted a special status. The guiding principle of the memorandum is that these areas may not be affected. Interventions are only allowed if these are of 'considerable importance for society', and if there is no other alternative available. In any case, loss must be kept to a minimum. If this proves impossible, the loss must be compensated.

The compensation obligation means that the affected nature must be replaced on a one-to-one basis, in terms of quality and surface area, preferably as close as possible to the place affected. For each tree and every square metre of nature that disappears, new plantings must be realised close by.