Botanical recording , distribution maps and species frequency

A standardised botanical survey technique was used to investigate sources of variation in botanical surveys used to produce distribution maps and assess species frequency, The most significant sources of variation between visits were the individual botanists; the number of habitats visited and length of route recorded also explained some variation. The number of records for each species increased proportionally with the amount of recording as species were encountered in essentially a random manner. The results demonstrate that as recording for atlas projects is unlikely to be comprehensive, care should be taken to obtain even coverage and minimise the variations in recording. Recommendations to improve the quality of atlas data are given.