AMOUNT OF LITTER PRODUCED. 767 



ash, elm, lime, Weymouth pine, sweet-chestnut, alder and hazel 

 is also dense though comparatively lighter than the above ; 

 oaks, poplar, birch, pines and larch close the list. 



The duration of the leaves on the trees is longest for 

 evergreen conifers, silver-fir, spruce and pines. In the case 

 of the black, Weymouth and Scots pines, the needles remain 

 from two to four years ; in the spruce and silver-fir, four to 

 six years and even longer for the latter. Hence it follows that 

 pines shed about one-third of their foliage annually, the spruce 

 and silver-fir only the fifth or sixth part. These species, there- 

 fore, are much worse producers of litter than follows from the 

 density of their foliage. 



Silver-fir, spruce and beech possess in the highest degree the 

 property of growing in densely stocked woods, next come the 

 hornbeam and hazel some way further down in the list alder 

 and sycamore. In the case of ash, elms, oaks, sweet-chestnut, 

 birch, aspen, Scots pine and larch, the woods open out much 

 earlier. As compared with woods of light- demanding trees, 

 those of mixed light-demand ers and shade-bearers produce 

 more litter, whilst woods of spruce, silver-fir and beech produce 

 litter most abundantly. 



(b) Locality. The nature of the locality in which it is grown 

 has the greatest possible influence on the wellbeing of a species 

 of tree. The more a locality suits a tree, the greater, other 

 conditions being equal, will be the production of litter. As a 

 rule, a moist atmosphere, provided there is sufficient heat 

 available for the species in question and a rich soil, increases 

 the density of the foliage. 



E. Weber's* note on beech leaf-production should also be 

 noted, viz., that it falls off in quantity with the altitude. 



(c) Weather. Any casual observer must have noticed that 

 according to the changes of weather in different years, the 

 forest presents different appearances, being in certain years 

 fresher, greener and possessing denser foliage than at other 

 times. Spring weather, when the foliage is produced, is most 

 decisive in this respect. Years with severe late frost and dry 

 seasons produce less foliage than moist years free from frost. 



* Ebermayer, " Die Waldstreu," p. 37. 



