130 Studies in Forestry [CHAP. vi. 



in the number of insects, as insectivorous birds are much 

 more frequent where broad-leaved trees exist than in purely 

 coniferous woods. But even where attacks of noxious insects 

 take place in such mixed woods, they seldom become wide- 

 spread over all species, and never necessitate the clearance of 

 whole crops, as unfortunately sometimes happens in the case 

 of Spruce and Scots Pine. 



Trees like the Oak, which are somewhat sensitive to late 

 frosts in spring during the early period of their growth, are 

 apt to suffer less damage whilst growing under the protection 

 of hardier kinds of quicker development, like Birch and Scots 

 Pine. And again, in mature mixed woods of conifers and 

 broad-leaved species, the technical value of the boles is less 

 likely to be diminished by frost-shakes than when these latter 

 are grown by themselves. 



The woodland proprietors, of Scotland especially, know 

 what ravages can be committed in pure Larch forests by the 

 fungoid disease, due to Peziza Willkommii^ which causes 

 a cankerous outbreak on the stems, and induces crooked 

 growth. And in pure woods of Spruce, Silver Fir, and Scots 

 Pine, red-rot and other fungoid diseases of the stem and the 

 root-system, occasioned by Trametes radiriperda, T. pini, 

 Aetidium elatinum, Peridermium pini, Agaricus melleus, &c., 

 are often productive of very serious sylvicultural and financial 

 results. Speaking of ' leaf-shedding] a disorder to which Scots 

 Pine is liable at an early age an infant ailment, due some- 

 times to frost, or to the drying-up of the needles when 

 stimulated to transpiration by bright sunshine in winter or 

 early spring, whilst the soil is still frost-bound and unable to 

 yield fresh supplies of moisture to replace that evaporated, 

 but in many other cases undoubtedly occasioned by a fungus, 

 Hysterium pinastri, Gayer says * : 



' About thirty years ago the sporadic occurrence of " leaf-shedding " in 

 Scots Pine was merely " an interesting observation" whereas now it is 



1 Der gemischte Wald, 1885, p. 24. 



