3.c. Comparability of Data Sources

3.c. Comparability of Data Sources

33 % of sources on species do not use taxonomic standards

An object for which data are collected must be identified and named. Animal and plant species surveyed for inventories or monitoring programmes are named using nomenclatures with varying degrees of standardisation according to species groups. For Mammals and Birds, the nomenclatures which are applied are often in common use. Less well known groups which are more important in terms of size, such as Invertebrates and Lower Plants have no standard lists of names in common use.

Following the question : « which taxonomic standard are you using ? » 10 % of sources use national standards, 10 % Flora Europaea, the rest being shared between 7 standards. Even if the number of standards is related to the number of species, 33 % of sources do not use standards at all.

Another important point is the utilisation of coding to make the management of data easier. Figure 17 shows that 47 % of sources have their in-house coding system and 24 % have no system at all.

43 % of sources on habitats do not use standards

Discussions on classification are on-going and work on standardisation is not well advanced.

In the results of the questionnaire, 7 classifications have been quoted including :

• CORINE classification

• Habitats Directive classification

• Nordic Vegetation Type

• UK National Vegetation Classification

Figure 17 : Taxonomic coding systems used by data sources in Europe

Various spatial units

To allow comparison between species and habitats distribution, a geographic reference system based on comparable spatial units is necessary.

Figure 18 illustrates the wide variety of types of units used.

It is also very difficult to compare the different grids used (50, 10, 2 km2, ...) since the associated type of projection is hardly ever specified for sources on habitats and sites; it is only specified for 50 % of sources on species.

Figure 18 : Spatial units used by data sources in Europe