CHAP, vi.] Advantages of Mixed Woods 133 



happens when swarms of caterpillars of the Processionary Moth 

 ( Gastropacha processionea) defoliate the Oak, for instance the 

 injury is not of a permanent nature, owing to the much larger 

 reserves of starchy matter accumulated by the broad-leaved 

 kinds of trees, and the stronger reproductive and recuperative 

 capacity with which they are consequently endowed. 



By admixture of broad-leaved genera, therefore, and parti- 

 cularly of Beech or Hornbeam, along with conifers, the danger 

 of attacks from insects can be greatly diminished without 

 prejudicing the other advantages derivable from the formation 

 of mixed crops. Thus Danckelmann states 1 that woods 

 which consisted of four-fifths Scots Pine and one-fifth Beech 

 or Hornbeam practically did not suffer at all in Prussia from 

 any of the insect calamities caused by moths between 1860- 

 1880, whilst the pure woods of Pine suffered severely. 



The beneficial effect of mixed crops in obviating extensive 

 injuries from insect enemies is perhaps almost the only point 

 concerning which German sylviculturists are absolutely unani- 

 mous. That such calamities as have from time to time 

 occurred in different parts of Germany have not taken place 

 similarly, though on a smaller scale, in any part of Britain is, 

 most probably, solely due to the happy chance or the prudent 

 sagacity of woodland proprietors imitating nature by the forma- 

 tion of mixed woods rather than pure forest over areas of 

 considerable extent. Experience on a large scale in Germany 

 has shown that the number of dangerous insects is not only 

 less in mixed than in pure crops, but also that at the same 

 time the number of insectivorous birds is greater. Should 

 Sir Herbert Maxwell's advice be extensively adopted, however, 

 the days of such comparative immunity will almost to a cer- 

 tainty be numbered. 



What is true about dangers from injurious insects, may also 

 be repeated as to windfall and breakage from storms, and to 

 damage wrought by accumulations of snow or ice on the 

 1 Zeitschrift fur Forst- und Jagdwesen, 1881, p. I. 



