BRITISH FOREST TREES 121 



of distribution and its warmer southern home, pure forests of 

 silver fir could scarcely be expected to yield in Britain, and 

 especially in Scotland, such favourable outturn of large 

 timber per acre as in southern Germany and France, so that 

 it seems here principally suited for admixture along with 

 some other ruling species. There are in particular three 

 cases in which the sylvicultural importance of the silver fir 

 can hardly be questioned, viz. firstly ', as its branches have 

 a considerable degree of elasticity, it suffers less from 

 breakage through snow or ice than either spruce or Scots 

 pine, and consequently minimises damage arising there- 

 from in mixed forests, wliilst being also less liable to infection 

 from root-rot (Tramctes radiciperdd) than the spruce, it 

 therefore in mixed forests hinders the disease from becoming 

 wide-spread and serious, and thereby directly improves the 

 ultimate outturn from the mature crop ; secondly, in forests 

 of broad-leaved, deciduous species, in which for obvious 

 sylvicultural reasons beech ought usually to be the principal 

 ruling species, the silver fir is on the whole better able to 

 accommodate itself to the peculiarities of growth of broad- 

 leaved trees, and in general yields better returns than other 

 conifers ; thirdly, as on suitable soil it bears more shade 

 than any other conifer, not even excepting the spruce, it 

 often yields excellent service when planted as underwood, 

 especially under oak or under Scots pine on a somewhat 

 binding soil, without losing the power of developing fairly 

 into good, useful timber when the overwood or standards have 

 been cleared for sale. In the filling up of blanks, where 

 the shade may be somewhat too great for even the spruce, 

 it is a welcome species except where frost is to be feared. 



When thrown in pure forests in southern (Jcrmany, it is 

 usually worked with an average rotation of 100 to 120 years ; 

 even on soils of average medium quality the outturn per 

 acre varies from 8,700 to 10,900 cubic feet per acre, as 



