The use of the axiophyte species concept to describe the ecological network of the Birmingham and Black Country of the UK West Midlands

The UK conurbation of Birmingham and the Black Country has recently been surveyed for a new Flora, on the basis of a 1 km square grid. The present paper uses the data to describe the ecological network of the conurbation. The total number of taxa per 1 km squares is shown to be moderately but significantly correlated, and the number of native taxa more strongly correlated, with the area of the previously-established network of protected sites. Nevertheless coincidence maps of total numbers or numbers of native species per 1 km square give only poor representations of the ecological network compared with maps of protected sites. Axiophytes are defined as plant species 90% restricted to conservation habitats and recorded in fewer than 25% of 2km × 2km squares in a county. Applying the concept to 1 km squares in Birmingham and the Black Country creates a list of 256 axiophytes. Numbers of axiophytes are shown to be more strongly correlated with areas of protected sites than total taxa or native taxa and a coincidence map of the axiophytes is found to provide a useful quantitative assessment of the ecological network. Maps of axiophytes are used to divide the network into core and linking areas and their use in consolidating and improving the botanical ecological network is explored.