IMPROVEMENT OF THE FOREST 201 



5. By the prompt removal of diseased and insect- 

 mfested trees further injur)' from these sources can be 

 prevented. 



6. The amount of inflammable debris on the ground 

 is less than where there are no thinnings. 



7. The trees are more windfirm. 



Theory of Thinnings. — The objective point is the 

 development of the dominant trees of good form. The 

 aim is to give them the space required for their proper 

 growth, with a view to a larger yield per acre, and the 

 maintenance of a degree of density of cover which will 

 maintain the soil in good condition. 



In making thinnings, therefore, the forester studies 

 the crowns of the trees and their position in the canopy. 

 He does not consider the number of trees per acre, or 

 the spacing between the trunks; his principal attention is 

 directed to the requirements for crown space of the trees 

 he seeks to develop. In order clearly to understand the 

 principles of thinnings, the reader should keep in mind 

 the distinctions between the different crown-classes, as 

 outlined on page 28, and illustrated in the diagram on 

 page 29. 



The methods of thinning most common in Europe 

 are those developed in Germany and to-day most exten- 

 sively practised in that country. The theory is to re- 

 move, first, the suppressed stand, and then such of the 

 intermediate and co-dominant trees as are required by 

 the local conditions and objects of management Dom- 

 inant trees are not cut, except in the case of indi- 



