AMOUNT PRODUCED. 



595 



Even-aged woods, therefore, do not produce as much annual 

 litter as uneven-aged selection-woods, double-storied woods 

 (with overwood and underwood) or woods managed according 

 to the group-system. Well-stocked coppice-with-standards on 

 good soil may yield annually even more litter than even-aged 

 high forest.* 



(e) Age of trees. — The greatest production of dead leaves and 

 needles is during the pole stage, and only slightly falls off in the 

 older stages of high forest, provided the leaf-canopy is fairly 

 complete. 



Whenever no direct experimental results as to the amount 

 of litter in a forest are available, estimates of the quantity of 

 litter are necessarily based on the physiological fact that the 

 annual production of foliage is very nearly proportional to the 

 annual production of wood. The results of the Bavarian investi- 

 gations has not so completely confirmed this rule as was 

 expected, but all sylvicultural observations tend to prove the 

 existence of a fixed ratio between the amount of foliage and the 

 wood-increment. 



The following results give the average yield of litter as deter- 

 mined by observation! made in the Bavarian State forests. 



One acre of dense forest of the ages given in the subjoined 

 statement produces annually so many tons of air-dried litter : — 



It is evident that when the litter is allowed to accumulate in 

 a forest for several years, the supply is greater than that pro- 



* [The apparent contradiction between tliis statement and that in (f), p, 589, 

 is due to the fact that here the annual supply of litter is referred to, and there, 

 the accumulated amount of litter undisturbed for years. — Tr.] 



+ Ebermayer, Die gesammte Lehre der Waldstreu, Berlin, 1876. 



Q Q 2 



