136 SCIENTIFIC SURVEY OF BLACKPOOL AND DISTRICT 



to grow up, they all contain a considerable abundance of small timber, mainly 

 hazel and birch, as well as a considerable variety of trees, many of which have 

 been introduced. Of the native trees, Pr units Avium is possibly the most 

 constantly and widely distributed species ; ash, elm and Prunus padus are 

 frequent in the damper places, while yew, Taxus baccata, may form dense 

 communities on the more broken rocky knolls and outcrops. 



The ground flora of these woods is less uniform than that of the typical dry 

 oak wood, and both mosses and ferns are more frequent. The community of 

 Scilla, Holcus mollis and Pteridium exists in various forms where the soil 

 exceeds nine inches in depth. More commonly, bluebells and Holcus occur 

 with an abundance of Mnium hornum, some Anemone and mosses such as 

 Hylocomium triquetrum. On damper slopes, particularly those with a 

 northerly aspect, this community changes to one in which Mnium hornum 

 is associated mainly with Oxalis acetosella, and ferns, Dryopteris aristata and 

 D. Filix-mas. At the bottom of slopes, dog's mercury and garlic (Allium 

 ursinum) are likely to be found, their commonest associate being the moss, 

 Eurhynchium praelongum. 



The characteristic feature of these woods is, however, the frequency of rocky 

 knolls, mainly covered by such mosses as Dicranum majus, Hypnum 

 cupressiforme, Plagiothecium undulatum and Leucobryum glaucum. The 

 higher plants are usually represented by bilberry (Vaccinium Myrtillus), 

 Deschampsia flexuosa and Luzula pilosa. Melampyrum pratense and its 

 variety hians are often found on or near these knolls. The soil is extremely 

 acid, usually below pH 5. Another common and wide-spread ground flora 

 is dominated more or less completely by grasses to the ultimate exclusion of 

 other herbaceous plants. The grasses usually include Agrostis spp., Holcus 

 spp., Festuca ovina and Anthoxanthum odor at um. In various modifications, 

 this grassy type of ground flora may occur over an extremely wide range of 

 soil types, and there is no doubt that it is developed mainly where grazing by 

 animals is or has been possible, although it is possible that the shallow soils 

 may also be a contributing factor in its development. 



The importance of the effects of grazing animals, here mainly sheep, rabbits 

 and to a less extent deer, can hardly be over-estimated in the Lake District. 

 The grassy and grazed type of woodland just described merges naturally into 

 the grasslands of the hill slopes. The absence of tree seedlings in grassy 

 woodlands indicates that such woodlands normally fail to regenerate and must 

 give way to grassland. The typical Lake District grasslands are, in fact, biotic 

 plant communities whose extension and maintenance depends on grazing. 

 The extreme importance of the pressure exerted by animals is not easily 

 realised, but it is at once apparent if one stands above one of the steeper slopes, 

 when the light is shining on it obliquely at an angle nearly that of the slope. 

 Then the slope is seen to be terraced by thousands of horizontal sheep tracks, 

 giving a most striking demonstration of the severity of animal pressure. 



It is probable that the grasslands have always existed above the tree limit, 

 and it seems equally probable that their downward extension has been going on 

 since the earliest times. The prehistoric remains in this district are confined 

 to the hill tops, and, moreover, they show a quite striking correlation with what 

 are to-day the best grazing grounds. It would seem logical to suppose that the 

 early inhabitants dwelt and pastured their flocks above the forest limits, and 



