Insularity and the Quaternary tree and shrub flora of the British Isles

The distribution of trees and shrubs within the British Isles and elsewhere in northern Europe is considered in the light of palaeoecological evidence for Holocene distributions. A small number of species appear to be capable of spreading across any seachannel in the region, and the overwhelming majority are capable of spreading across channel of 10-100 km extent. Thus, there is little evidence that insularity would have been a significant factor in controlling the tree and shrub flora in the present or previous interglacials, and hence the presence or absence of any species cannot be used as evidence or otherwise for isolation. However, there have been significant losses of tree and shrub species from islands during the late Holocene as a consequence of anthropogenic activities. These may be among the more dramatic prehistoric extinctions yet described.