Change in species distributions at tetrad scale – a supplement to Change in the British Flora 1987-2004

Abstract

The report on BSBI’s ‘Local Change’ repeat tetrad survey (LC) was published in 2006 as Change in the British Flora 1987-2004. Excellent species distribution maps at tetrad (2 km) scale are now readily accessible on BSBI’s online Distribution Database (DDb). The opportunity has been taken to download a selection of such maps and match them with the species chosen for detailed accounts, including maps and statistics, in the LC Report. Statistics on species distribution change at tetrad scale have also been derived from data extracted from the DDb for England and Scotland comparing the dateclass 1987-99 with 2000-19. Further statistics have been derived for Bedfordshire v.c.30), where two complete surveys at tetrad scale have been completed. The statistics of change for the chosen species are expressed as ‘% Change per decade’. Taken together, the maps and statistics provide greater insight into the geographic patterns of change than was available at the time of the LC Report.