ABUNDANCE-RANGE SIZE RELATIONSHIPS IN THE HERBACEOUS FLORA OF CENTRALENGLAND

1 Using data from a survey of over 10000 l-m(2) quadrats in a 3000-km( 2) area, we examined the relationship between abundance and range for the vascular plant flora of central England. 2 At the level of the who le landscape, abundance was not related to local, regional or national range. Local, regional and national range were closely related to eac h other. 3 At the level of the whole landscape, range was significantl y and positively related to both niche breadth (expressed as the range of habitats exploited) and to habitat availability, although niche br eadth appeared to be more important. Abundance was not related to nich e breadth or habitat availability. Since specialist species are mainly confined to uncommon habitats (especially wetlands), we conclude that the relationship between range and niche breadth is not an artefact o f widespread species passively sampling more habitats. 4 At the level of individual habitat types, significant positive relationships betwee n range and abundance were common. These relationships remained after controlling for the effects of phylogeny. For predominantly annual wee d communities, the relationship was linear, but for perennial communit ies it was markedly 'upper triangular', i.e. all combinations of range and abundance were found except wide range/low abundance. The evidenc e suggests that this difference can be attributed to the greater mobil ity of annual weeds.