Trees of Britain and Ireland

Abstract

the particular species in relation to its ecology. In comparison with old-style listing of localities, which is here greatly reduced, it is important to recognise that a tetrad is four square kilometres; a large area to search. I have a special interest in the discovery of Sesleria caerulea in Monksdale which, with Cressbrook Dale, I surveyed in detail in 1957/8 on behalf of the then Nature Conservancy. It is a locally common grass on the north Pennine limestone, but that is 70 km distant and, unlike Geranium sylvaticum, scarcely likely to be a garden escape. Dare one suggest it was planted there (see Alchemilla alpina on p. 103), perhaps as an unrecorded experiment, or worse, as the new fashion of believing that planting of native species is conservation? Such interference may negate the value that detailed maps on this scale have in providing information on the changes in distribution of species in response to, for example, climate change. The maps for Brachypodium rupestre (syn. pinnatum), a calcicole grass at its north-western limit in Derbyshire as a common species, shows a three-fold increase in number of tetrads between Clapham’s Flora (1969) and the new Flora (2015) mostly on the Magnesian limestone, but many of the earlier records in the dales were not recorded subsequently, despite the normally aggressive behaviour of this grass. The history of the study of the flora in the third chapter illustrates not only the contribution of academic botanists in nearby universities, but also of the numerous expert amateurs who it was a delight to accompany for their field knowledge: a steel worker or industrial chemist on weekdays and a fund of knowledge on natural history at weekends. Of six more mostly short chapters, number five is outstanding and probably unique: it provides short but informative descriptions and a photograph of 55 sites scattered over the county where the richness and diversity of the flora and vegetation can be experienced. This chapter and the first are enough to make the book outstanding.