Introduction

The Maps Scheme, launched in 1950, is the world’s oldest natural history distribution mapping project. It is constantly updated and improved by the BSBI’s networks of volunteers, county recorders and referees, and it is always in use by scientists, conservationists and governmental bodies for determining the abundance, range and change of vascular plants and charophytes in the British Isles.

The Tetrad Maps Scheme

The next step will be to change the resolution of the dots from 10km to 2km. Many counties have done this already, but coverage is far from complete. For the rarer species the tetrad maps are quite comprehensive, but for commoner plants they simply show the counties that record at tetrad scale.

If you would like to see how the Tetrad Maps Scheme is developing, have a look at the maps, but be aware of the limitations of the data so far.

Note that the tetrad Maps Scheme does not display date classes. Change is only one of the attributes that can be seen on a map - these are far more interesting for showing distribution, as opposed to range. For species with particular habitat requirements, it is often easy to pick out the geology or the landscape where they occur.