1904 



FORESTRY AND IRRIGATION 



iSg-j-'gS, the proportionate yield of 

 each method stood as follows : 



C thinning, 100 per cent. 



Borggreve, go per cent. 



Selection thinning, 82 per cent. 



At the second thinning, in i9O2-'c>3, 

 the result had changed to : 



C thinning, 100 per cent. 



Borggreve, 65 per cent. 



Selection thinning, 82 per cent. 



Although this experiment has not 

 progressed far enough for definite re- 

 sults, it seems already to show the im- 

 practicability of the Borggreve method. 

 On the other hand, the position of selec- 

 tion thinning is better than the propor- 

 tion would seem to evince. The stand 

 was heavily cut into and has not had 

 time to recuperate. The general ap- 

 pearance of the trees is better than by 

 any method and the total increment is 

 largely in the trees chosen for the final 

 stand. The author expects that this 

 method will finally give the best results 

 of any system. 



CONCLUSION FOREST THINNING IN 

 AMERICA. 



The European results here summa- 

 rized would have no interest or value in 

 this country were it not for the useful 

 experience which may be adapted to 

 American conditions. German forest^ 

 is intensely conservative and has devel- 

 oped very slowly. This is especially 

 true in regard to thinnings, as it may 

 be safely asserted that four- fifths of the 

 forest land today is not thinned beyond 

 the A or B grade of the Tharandt experi- 

 ment. Hartig, who practically founded 

 the art of forestry at the end of the i8th 

 century, laid it down as an axiom that 

 no dominant trees should be cut and the 

 cover never broken in thinning. In 

 spite of modern teaching, his influence 

 seems to still live, and the average thin- 

 ning yields but a comparatively small 

 amount of low-grade wood. Such a 

 method may pay well enough in a coun- 

 try where wood is so dear as in Ger- 

 many, but in America this timber could 

 be removed only at a loss, and there- 

 fore could not be touched at all. Hence 

 it is of the greatest importance that a 

 method of heavy thinning shows the 

 best financial results in both the final 



and intermediate yields. If a correct 

 system gives large enough timber to 

 make thinning pay, we can begin our 

 experience with all the accumulated 

 knowledge of Germany behind us and 

 save ourselves time and trouble by com- 

 mencing on the right track. 



Of course, it is evident that it is only 

 possible to practice thinning in a small 

 part of the American forests. Through- 

 out the great lumbering regions they 

 are not to be considered at all, but there 

 is a large area of country in the north- 

 east where thinning should often pay 

 if properly managed. In parts of New 

 England, New York, Pennsylvania, 

 Ohio, and Indiana there are numbers of 

 woodlots and timber tracts which could 

 be profitably improved by systematic 

 thinning. 



The tree classification is the most im- 

 portant and difficult preliminary to an 

 effective system. The trees should be 

 divided into enough classes to make 

 several degrees of thinning quite dis- 

 tinct from each other, and at the same 

 time the division should be so broad 

 that there is no doubt of the class to 

 which ever> r tree in the stand belongs. 

 The classification given in Part I is not 

 difficult to apply after a little practice, 

 but for American conditions the follow- 

 ing plan seems more advisable : 



Class I. Dominant. Trees which 

 make the upper forest cover. 



a. Withsymmetrically formed crowns. 



b. With unevenly developed crowns. 

 Class II. Overtopped. Trees which 



have fallen in growth below the upper 

 forest cover. 



a. With crowns free to the light. 



b. With crowns directly shaded, but 

 still thrifty. 



c. Dying or dead. 



This grouping is less arbitrary than the 

 other and follows nature more closely. 

 Its simplicity will make it easy to apply 

 to the conditions of the average wood- 

 lot. Trees belong to Classes I and II 

 only in relation to their immediate 

 neighbors. An individual which from 

 its size belongs to Class II in one part 

 of the forest may be in Class I where 

 the general average is smaller. 



As wood is cheap and labor dear, it 

 follows that thinning will not pay until 



