According to the current legal background for the regulation of genetically modified plants (GMPs) in Europe, an environmental risk assessment (ERA) has to be performed considering i) the crop plant, ii) the novel trait relating to its intended effect and phenotypic characteristics of the GM crop plant and iii) the receiving environment related to the intended use of the GMP. However, the current GMP-ERA does not differentiate between different intended receiving environments. Therefore, the question is to be raised: How can the ’receiving environment’ be classified on the European scale, both in an ecologically relevant and feasible way? As a first step this proposal focuses on invertebrates in the terrestrial environmental compartment. In order to check if already existing regionalization concepts are suitable for the above raised question the following selection criteria were employed:

•	Distribution of non-target organisms (NTOs): A suitable regionalization concept should appropriately reflect the specific characteristics of the animal and plant communities of the different receiving environments of a GMP. Therefore, such a classification should be done by an ecoregion approach, meaning that different ecoregions support different organism communities that may play a different role in supporting relevant ecosystem services. However, information on the distribution of invertebrates in Europe is not available in sufficient detail for this purpose. Hence, it is proposed to use the information about site conditions like climatic, vegetation and soil parameters, which determine the composition of invertebrate communities, for the selection of an appropriate classification concept.
•	Size and number of geographical units: This is a trade-off between the total number of ‘receiving environments’ in Europe manageable in a regulatory context and the ecological uniformity of a single geographical unit. An intermediate size and number of geographical units should be the aim of the classification.

With the ‘Indicative map of European biogeographical regions’ (IMEBR) there is an existing regionalization concept that meets many of the requirements identified above: the classification is based on parameters that also determine the distribution of invertebrate communities (i.e., the potential natural vegetation) and nine biogeographical regions represented within the 27 member states of the European (EU-27) are a manageable number for regulatory purposes. However, epigeic (living above ground) and endogeic (living below ground) faunal communities are determined by different biotic and abiotic parameters. For example, climate data is much more relevant for epigeic species than for endogeic organisms. The most important soil properties related to the distribution of endogeic organisms and plants are pH, texture, organic matter content and/or content of organic carbon, C/N ratio, and water-holding capacity. Hence, for endogeic non-target organisms there is currently no suitable regionalization concept available. For the time being, it is recommended to identify important species for testing purposes in each ecoregion with GMP cultivation by means of expert knowledge using the IMEBR for both epigeic and endogeic communities.

The regionalization concept is intended to be used in the context of the ERA of GMPs for the assessment of risk for NTOs. Hence, it should be tailored for the area in the EU where GMPs are likely to be grown. The overlap between the biogeographical regions and the intended area of cultivation for a novel GMP form the different cases, each of which should undergo a specific ERA process.

For example, there would be eight or nine separate potato cases for the EU-27 area, i.e. the Alpine, Atlantic, Boreal, Continental, Macaronesian, Mediterranean, Pannonian, Steppic and possibly the Black Sea biogeographical regions. For grain maize there would be five to nine separate cases, i.e. the Atlantic, Continental, Mediterranean, Pannonian, Steppic and possibly the Alpine, Black Sea, Boreal and Macaronesian biogeographical regions.