Recording & Support -
Help & Advice
Grid References
7. Uses of Different Grids
You may be asking why we need so many different types of grid reference. This is because each has their own use, and some methods are more appropriate than others to use whilst recording.Remember, grid references can always be 'dumbed-down' later without the help of the original recorder, but cannot be made more accurate.
If a record has a grid reference at the 1km level of TR1246, you can determine that it resides in the 10km square TR14, but you cannot determine which 100m square the record resides in. Consequently, you should always record as accurately as possible when appropriate.
Uses of different grid references levels are as follows:
100km level -
only ever used (although rarely) for distribution mapping for very large areas, e.g. European distribution (although it should be stated that the rest of Europe does not use the British National Grid system).10km level -
usually used for national distribution mapping of a species.5km level -
this method is not often used in recording, but is used to divide large digital maps or aerial photographs for ease of use.2km level -
this method is mainly used by recorders wishing to map species at a local level, such as the Kent distribution. It is useful in showing the rarity of a species or broad abiotic associations, but not for locating individuals. It is also used by some national recording schemes, e.g. Botanical Society of the British Isles, for monitoring purposes.1km level -
this method is also used for mapping local distributions, giving a more accurate picture, although it is sometimes the most accurate grid reference that can be determined from a map, depending on the scale of the map and the amount of detail present.100m level -
this is the most accurate grid reference you can reliably obtain from a standard OS map. It is also the level obtained from the internet using the postcode to determine location. This is the level at which most species are recorded.10m level -
a GPS unit is required to accurately record at this level. Most GPS units record at the 1m level (see below), although if you cannot get a good accuracy due to environmental factors, or if something covers a 10m x 10m area, then this is the best level to record.1m level -
a GPS unit is required to record at this level, and this is the most accurate location possible. It should be noted that although this is theoretically recording at the 1m x 1m level, this is rarely the case, as GPS units always carry a level of inaccuracy due to environmental factors. Consequently, when recording using a GPS, you should always note the level of accuracy given by the GPS unit.
Although it may be possible to record certain species at very accurate levels with the use of a GPS, this is not always appropriate due to the species' ecology. If you have located a rare plant, the most accurate location possible should be given, as plants are generally not mobile, and so an expert could use the locational data to find the species and verify or invalidate that record. Highly mobile species do not need to be recorded at such an accurate level. Birds are often recorded only at the 1km level, unless the area of habitat they are found in is small, such as a small reedbed, or if recording a breeding site. However, this does not always apply and also depends on the state or aspect of the species. A fox may be recorded at the 1km or 100m level, but if it is found dead on the side of the road, or you have located a fox den, a more accurate location should be noted.
Ultimately, if you have any questions about recording the location of a species, or any questions about recording in general, please contact the KMBRC.
