An interesting bit of documental evidence from Richard Bland, on the importance of Bristol99’s work for our heritage…..
During May and early June this year there were five events supported by the Friends of the Downs and Gorge, supported by the Bristol99 project and the Gorge and Wildlife project based at Bristol Zoo. One was rained off, three were poorly attended as a result of my publicity failures, and the last involved a class from Clifton College lower sixth. The Downs is both a very substantial SNCI site consisting of some 200 hectares and the gorge edge is an SSSI. The Bristol 99 visits were designed to survey the common plants of twenty specific hectare squares, covering a variety of different habitats. They used tick lists as a simple way of producing an accurate but not complete species list. In the event 15 of the squares were covered at the time, and sub sequentially, inspired by the success of the scheme, all 200 of the tetrad squares of the SNCI were surveyed.
The Bristol99 visits were based on lists of some 30 common species expected at each site, and subsequent work has shown that this is indeed roughly the average number of plant species, excluding grasses, in each hectare. The extremes are 88 species and 7 species The survey also showed the extraordinary variety, and fragility of the Downs species list- over 70 species were found in a single hectare square, and a similar number were present in ten percent or less of the regions one-km squares. There were six very different habitat types present, the cliff face itself, parkland, ie essentially grass and trees, closed canopy woodland, scrub, football pitches, and limestone species rich grassland. This is the rarest habitat both on the Downs and in the region and it dominated as few as 14 of the squares. There were some 42 uncommon species associated with the limestone grassland, eight of them only found in a single square, but Catsear, the commonest found in 58.
This survey has shown the wonderful botanical diversity of the Downs and its extraordinary variety, and will act as a yardstick for the process of change which is continuous on the Downs, partly the result of the spread of scrub, partly a response to differing mowing regimes, partly a more natural response to varying weather conditions.
Bristol99 