JIRITISII FOREST TREES 27 



Whilst woody plants suffer little from frosts during winter, 

 the late frosts in spring and the early frosts in autumn 

 often occasion very considerable damage, especially to young 

 growth. Danger from frost is greater on plains than in hilly 

 tracts ; greater on south and south-eastern exposures than on 

 northern and western ; greater in valleys, and coombs, and 

 basins, than on ridges and shoulders ; greater in localities 

 protected from the wind than in those where currents of air 

 have free play ; greater in a dry state of the atmosphere than 

 in a moist ; greater on fresh soil than on dry ; greater on 

 loose sandy soil than on stiffer loam. 



With reference to their liability to suffer from frost Gayer classifies 

 the forest trees as follows: Liable Ash, acacia, sweet chestnut, 

 beech ; less liable oak, silver fir, maple and sycamore, spruce, and 

 common alder ; hardy lime, hornbeam, elms, birch, larch, aspen, 

 Austrian and Scots pines (pp. cit. p. 21). 



The liability to suffer depends, however, less on the 

 species than on the stage of growth to which the young 

 shoots have advanced ; it is greater in weakly than in healthy 

 and vigorous plants ; greater too in plants suddenly exposed 

 after having long had the shelter of standards than in 

 those that have been gradually accustomed to the loss of 

 shelter. 



By comparison of the development of trees of the same 

 species, growing on soils of nearly equal quality, but in 

 localities known to differ greatly as to the relative humidity 

 of the air, it has been concluded that spruce, alder, maple, 

 sycamore, and ash, also in a less degree silver fir, beech, 

 and birch, thrive best in localities where the air has a high 

 degree of relative humidity. On the Continent the principal 

 tree on the dry sandy North-German plain is the Scots pine, 

 which though it thrives in the insular climate of Britain does 

 not thrive in the damp climate of Schleswig-Holstein ; whilst 



