The grid mapping , and grid pattern mapping called, is now the most common method for detection of biological species in a certain area. The cartographic and methodological foundations of the respective inventory surveys still vary regionally and internationally despite many efforts to standardize them, as does the subsequent presentation of the results. One of the most common cartographic bases for data acquisition is a minute field , which the mapper subdivides into smaller rejons, the extent of which is also dependent on the relief of the mapping area, which should be scanned as frequently as possible during the data collection period, which is usually several years.
The mapper (here using the example of birds) determines the qualitative presence of species according to various criteria:
- possible breeding: the species is present in a suitable habitat during the breeding season, but no clear breeding indications were found.
- Probable brood, but no brood evidence: clear brood indications could be observed (nest building, copulating pairs, clear territory behavior, brood spot ).
- Brood has been proven: fledglings have been seen; the brooding adult bird could be observed; Young were heard or seen in the nest; Young are being fed or adult birds have been seen with food.
A basis for floristic mappings in Germany is the measuring table sheet (topographic map 1: 25000), on which a grid of 4 × 4 cm in each case according to the Gauß-Krüger coordinate system is printed on a scale of 1: 25000 each corresponds to 1 × 1 km. A location can be localized on the measuring table in several stages from rough to precise. The roughest level is the indication of the table sheet number. The most accurate are right and high values with pinpoint accuracy (Gauß-Krüger coordinates). The small 250 × 250 m field is often used. To do this, a square kilometer field is divided into 16 squares of the same size, numbered vertically from 1 to 4 and horizontally from a to d. Nowadays, however, precise coordinates should be given preference, especially through the use of GPS .
In many fields of botany and zoology , grid mapping plays a very important role. The results of raster mapping are published not only in specialist articles but also in very extensive dissemination atlases.
Readers of such publications, who are not exclusively scientifically oriented, should bear in mind that inventory figures must be extrapolated from basic mapping data and can therefore often be subject to a very large spread and a very large degree of uncertainty. Some species are very difficult to map, some areas are inaccessible and are therefore less intensively explored. The respective specialist knowledge of the mostly volunteer mapping workers can also influence mapping results.
- Colin J. Bibby et al. : Methods of field ornithology. Inventory in practice. Neumann Radebeul 1995. ISBN 3-7402-0159-2
- Peter Suedbeck et al. : Method standards for recording breeding birds in Germany . Radolfzell 2005: pp. 456–457 ISBN 3-00-015261-X
- Arno Wörz, Martin Engelhardt: Floristic mapping of Baden-Württemberg: mapping guidelines . Central office for the floristic mapping of Baden-Württemberg, State Museum for Natural History Stuttgart, 2008.