The Nature Index assesses intervention alternatives by awarding points to areas (hectares) of nature. The higher the quality or the more highly valued, the more points an ecotope gets. The method then compares alternatives by the number of points received. The points are preferably based on (inter)national criteria as set out in policy documents such as the Water Framework Directive or Natura 2000. When objective criteria are lacking, points will be based on expert judgement.
The origin of the nature index tool lies within the Netherlands Environmental Assessment Agency (PBL), the national institute for strategic policy analysis in the field of environment, nature and spatial planning (Sijtsma et al., 2009). The agency has developed a method to assess the permanent effects of policy alternatives for terrestrial nature. In the ‘Building with Nature’ innovation programme this method has been developed further, which now applies to all natural systems, including aquatic/ marine systems. In addition, anticipated changes over time can be included, which enables valuation of dynamic as well as static effects of interventions.
Building with Nature interest
A system analysis approach facilitates the assessment of changes in ecological quality rather than ecological status
Building with Nature strives for tuning and optimization of infrastructural designs and natural processes. It also aims at increasing natural values, existing as well as new ones. Quantifying the effects of infrastructural works on natural processes requires a system analysis, which is provided by the Nature Index approach. The overall philosophy of the (eco)system analysis is that nature values can increase if the required abiotic conditions are provided. Large infrastructural projects and/ or measures to improve the ecological status of an area do affect these abiotic conditions. Indirectly – via system relations – they may also affect the relevant indicator species. Therefore, a system analysis is necessary to identify the ecological impact of such projects. Although this may seem obvious, many ecological studies, and sometimes even legislation, focus on the ecological status (by means of indicator species), rather than the change in ecological quality resulting from interventions in the system.
The tool enables a budget approach to nature values, providing the flexibility needed for multi-functional (integrated) design processes
Building with Nature designs aim at multi-functionality, including ecosystem services and nature values. This means that a balance has to be found between different functions. A budget approach can be of use here, provided that relevant values can be expressed in an adequate ‘currency’. When applied to nature values, with the Nature index as a currency, such a budget approach leaves room for compensating negative effects with positive ones. So far, this budget approach remains to be widely accepted. Now it is still possible that a measure with a positive nature index gets a negative score in an environmental impact assessment because it has a negative effect on a legally protected indicator species. For this reason, we expect budget approaches to become more widely used in the future.