CHAP, vi.] Advantages of Mixed Woods 131 



nothing short of a wide-spread calamity all over Germany. At first, two 

 to four-year-old seedling growth was chiefly attacked, but nowadays 

 sowings and plantations are both liable to be affected, and it is even be- 

 ginning to attack young thickets. And wherewith shall we replace the 

 Scots Pine, if even it refuse to serve our purposes? R. Hartig says, at 

 page 40 of his book on the Diseases of Trees 1 : " the best prophylactic 

 measure against the occurrence and spread of epidemics is the cultivation 

 of mired forest crops." ' 



A direct and fuller quotation may, however, also be per- 

 mitted from Professor R. Hartig's celebrated work, in which 

 the opening words of the Introduction are : 



' The transformation in the natural woods of Germany, the formation 

 of pure, equal-aged crops of the same species of trees, instead of the 

 composite mixed forests and copses made up of all sorts of trees of all 

 ages, and especially the restriction of the broad-leaved species by the 

 formation of pure crops of conifers, have during the present century, 

 and most particularly in the last few decades, threatened the well-being 

 of our woods to an extent which was formerly unknown. And it is 

 chiefly the enemies belonging to the animal and vegetable kingdoms 

 which find in the recent developments of our woodland economy the 

 conditions favourable to their increase in enormous strength, so that the 

 complaints made concerning larger and ever larger devastations, appear 

 in no wise unfounded.' 



But it is perhaps more with regard to damage caused by 

 injurious insects, than in any other way, that the beneficial 

 effects of the formation of mixed crops may be judged of, so 

 far as Spruce and Scots Pine are concerned. Simultaneously 

 with the disappearance of the natural mixed crops, which can 

 be proved to have formed the chief portion of the wooded 

 areas throughout Germany during the first quarter of the 

 present century, and with the formation of extensive pure 

 forests of coniferous species, the damage done by insect 

 enemies has increased enormously, and has on several occa- 

 sions during the past half-century attained the dimensions of 

 actual calamities, sometimes of national importance. 



Thus, referring to the ravages of the Black Arches, * Nun/ 



1 Lehrlruch der Baumkrankheiten, 1882 (2nd edit. 1889, p. 55). 

 K 2 



