INFLUENCE OF DIFFERENT DEGREES OF THTNNING ON BEECH. 119 



with light thinning, while the growth on the strongly thinned 

 areas is five or six times that of the latter. On two areas, again, 

 the increase of growth of the stronger stem classes on the a and b 

 thinned sections showed no important difference, while the growth 

 on the same stem classes on the strongly thinned sections was 

 from 25 per cent, to 100 per cent, higher than that on the former. 

 The ages of the trees on the various areas referred to above 

 ranged principally from thirty to eighty years; the majority, 

 however, lying between forty-five and sixty years. 



Light-Felling. 



The areas devoted to this research were divided into three 

 groups, and treated by the following methods : — 



1. Borgreve's method of light-felling. 



2. A method adopted by the Research Association. 



3. Seebach's system of treating beech high forest. 



No. 1 method was only a step in advance of the d thinning 

 carried out in the thinning experiments, and was observed in 

 conjunction with a control aiea (strongly thinned) in Frienwalde. 

 In 1887, 34 per cent, of the stem sectional area was removed, 

 leaving the equivalent of 75 per cent, of the sectional area pre- 

 sent on the control plot. The result of this treatment was par- 

 ticularly good, showing within the ten years an increase of 25 per 

 cent, of sectional area and 26 per cent, of volume over the control 

 plot. The removal of the badly-shaped and broad-crowned trees 

 benefited the growth of the middle-class stems greatly, and the 

 growth of adventitious shoots on the stems was but slight ; and 

 it is questionable whether the removal of hopelessly suppressed 

 stems is at all prejudicial in this respect. 



In order to ascertain the effect of removing predominant stems 

 from their neighbours, observations were directed to four groups, 

 two of which stood on the light-felling sections and the other 

 two on the control area. The trees were tested with the growth- 

 borer, and the growth during the five years preceding the com- 

 mencement of the experiment taken as the unit. On the control 

 area the growth during the five years following the date of light- 

 felling was 79 per cent, and 77 per cent, respectively of that of 

 the preceding period, while on the light-felling area it rose to 

 138 per cent, and 238 per cent, of that of the preceding period. 



2. Light-felling Research, arranged by the Research Association. 

 — This consisted of a strongly-thinned control area and two sub- 



