THE VEGETATION OF WOODLANDS I 9 



ground-vegetation includes fewer species. In wood after wood 

 of the dry type there may be little else than bracken, wood 

 hyacinth {Scilla) and soft-grass [Holcus mollis). Wood sage 

 {Teucrium Scorodonia), foxglove, tormentil {Potentilla), and the 

 rock bedstraw {Galium saxaiile) are also useful indicator plants, 

 not always confined to woods. In some dry oak-woods, blaeberry 

 ( Vaccinium Myrtillus), ling {Callima vulgaris) and the heath hair- 

 grass {Aira flexuosa) form a characteristic ground-vegetation. 



The oak-birch-heath association is the term applied to a 

 scrubby wood common on light sandy soils in the south-east of 

 England. Careful observations have been made on many of 

 these areas, and there is reason to believe that in some cases 

 they represent a stage of degeneration from the dry oak-wood 

 to heath, as a result of constant felling and neglect. Oak does 

 not seem to rejuvenate well, but birch comes abundantly from 

 seed. In places beech has secured a hold, and by its deep 

 shade clears out the ground-vegetation. Scots pine is another 

 successful tree which spreads rapidly from plantations, so that 

 considerable tracts of these southern English heaths are being 

 rapidly converted into seedling pine-woods. 



The birch-wood association is of more interest to northern 

 readers. In the hilly districts of the north of England, the oak 

 becomes rare at altitudes of about looo feet, whereas the 

 pubescent birch {Betula tomentosd) ascends higher. The oak 

 which is dominant in the lower valleys becomes stunted higher 

 up, and the birch increases until it gives the tone to the higher 

 woodland. The cause of this cannot be traced to soi4 conditions, 

 and it appears to be an effect of climate. Rowan, hawthorn 

 and some willows almost exhaust the list of trees and shrubs in 

 the birch-wood. The ground-vegetation, as a rule, does not differ 

 much from the adjoining moorland on the one hand, and the 

 poorest type of oak-wood on the other ; it may consist of wiry 

 grasses, dry heather and blaeberry, or wet moor with peat-plants. 

 We have seen fairly good examples of this type of birch-wood 

 in the higher valleys of the Lowlands of Scotland, In the 

 Highlands birch-woods are much more evident, and a special 

 colour is allotted to them in the vegetation maps of Perthshire 

 and Forfarshire. ^ The typical Highland birch, as seen by us 



1 "Botanical Survey of Scotland," by Robert Smith: II. Northern Perth- 

 shire, 1900 ; III. and IV. Forfar and Fife, 1903-4 {Scottish Geographical 

 Magazine). 



