766 FOREST-LITTER. 



From the above considerations it is evident, that forest litter 

 is one of the most important factors in the productivity of 

 the soil. As in forestry, where practised on a large scale, 

 it is impossible to substitute manure for litter ; normally 

 decomposed litter by its physical and chemical properties 

 and its effects on the soil, is indispensable. 



SECTION IV. AMOUNT OF FOREST-LITTER PRODUCED. 



Owing to the importance of moss and weeds as well as dead 

 leaves and needles in the supply of litter for farmyards, the 

 different nature of these kinds of litter and the various ways in 

 which they affect wood-production, itis necessary to consider the 

 question separately for each kind of forest litter. 



1. Dead Leaves and Needles. 



Experience shows that the annual amount of litter produced 

 from dead leaves and needles in a forest varies with the species 

 of tree, locality, weather, density of crop and age of trees. 



(a) Species of Tree. Three factors have great influence on 

 the amount of litter produced by European forest trees ; namely, 

 the density of the foliage, its duration on the trees and the 

 suitability of the species to form a more or less dense leaf- 

 canopy. Considering all these factors, not for individual trees 

 but for a crop of trees, and deducting the amount of moss pro- 

 duced in coniferous forests, the species may be arranged, as 

 follows, in descending order of their comparative production of 

 dead leaves or needles : 



Beech ; 



Sycamore and other maples, lime, sweet-chestnut, hazel ; 



Hornbeam, alder, black pine ; 



Elms, oaks, black poplar ; 



Scots pine, larch ; 



Spruce, silver-fir; 



Ash; 

 Birch, aspen. 



The density of foliage of a species depends on the nature of 

 the locality and its mode of growth. Silver-fir, spruce and 

 beech have the densest foliage ; that of hornbeam, sycamore, 



