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Biological value

Description​

Originally, the Nature Value Explorer only offered an evaluation of the provision of ecosystem services by alternative layouts of areas. In the recommendations of the tool it was indicated to add the biological and relational values in addition to the values calculated in the tool in order to have a complete picture of the values that open space generates.

The question to include the biological value in the tool came quickly because

  • An improvement of the biological quality (e.g. restoration of a malfunctioning ecosystem, increase in biodiversity) is often described qualitatively.
  • The improvement is usually not reflected in the valuation of ecosystem services if the same land use class is maintained.

We base the biological value method on the valuation of the Biological Valuation Map (Vriens 2011). The Biological Valuation Map (BWK) shows the nature of the whole of Flanders and Brussels. It indicates what the soil is covered with in a certain place (e.g. buildings, grassland, forest, ... ), what vegetation you find there (e.g. wet heathland, alder marsh forest, ... ) and which small landscape elements occur (e.g. hedges, rows of trees, drinking pools for cattle, ...). The map also indicates how biologically valuable a particular zone is.

Qualitative appreciation​

To make the maps easier to interpret for policy, a biological evaluation was carried out. A grounded and fixed valuation was assigned to each raster cell based on 4 criteria:

  • Rarity is a commonly used criterion for valuing species and biotopes. It indicates how often a species or biotope occurs within a certain area. In this case it concerns the area within the total territory of Flanders and Brussels.
  • Biological quality takes into account the diversity of species (plants and animals) that the biotope can contain if it is well developed, the possible presence of less common species and the refuge function for endangered species.
  • Vulnerability relates to the extent to which a biotope is sensitive to changing environmental conditions (as a result of e.g. pollution, eutrophication, desiccation, wetting, trampling, ...).
  • Substitutability indicates the extent to which the biotope can be recreated in another place, taking into account the time required to achieve an ecological balance and good quality.

The global fixed valuation consists of the following classes

  • Very valuable
  • Complex of valuable and very valuable elements
  • Valuable
  • Complex of less valuable, valuable and very valuable elements
  • Complex of less valuable and very valuable elements
  • Complex of less valuable and valuable elements
  • Less valuable

The Nature Value Explorer presents three scores. For the first score, we use the overall assessment and the underlying assessment of the four criteria directly from the BWK (updated version) for the current situation.

A second score provides the overall assessment and the underlying assessment of the four criteria based on current land use as shown on the land use map. We do this because the BWK has not been updated in some places since 1997 (see principles).

For this purpose, we have classified all the BWK land use mapping units within the Nature Value Explorer. Based on the mapping units within a specific measure and the assessment of these mapping units, the quality of the land use for the four criteria was assessed using expert judgment, and the overall assessment was then made.

The third score represents the overall assessment and the underlying assessment of the four criteria based on future land use. This can then be compared with score 2 to see how the biological value improves or deteriorates.

Quantitative and monetary valuation are not possible.

Assumptions​

  • When taking nature restoration measures, we will aim for the most valuable form of a land use type.
  • BWK is up to date for the studied area. This is not necessarily the case because the BWK is only updated annually for a number of areas because of the resources required for mapping and monitoring. We recommend comparing data for which the site visit has been conducted less recently with recent orthophotos to determine whether any changes are likely.
  • The value for fauna is currently not taken into account.
  • No potentials or landscape relationships are displayed via the valuation in the BWK. The valuation corresponds to the biological value of each individual biotope in its current condition and at plot level. It therefore does not take into account the landscape context.

Translation to indicator​

As an indicator in the dashboard we use the increase/decrease of valuable to very valuable biotopes within the study area based on the global valuation.