764 FOREST-LITTER. 



(a) Kind of Soil- Covering. Soft and only slightly lignified 

 parts of plants decompose most rapidly. Thus, of broadleaved 

 trees, the dead leaves of the hornbeam, ash and lime decom- 

 pose more rapidly than those of oak, beech and birch. Of 

 conifers, larch needles are decomposed soonest, then Scots pine 

 needles, those of silver-fir, and most slowly, those of spruce. 

 ]t is generally true, that dry leaves of broadleaved trees 

 decompose more rapidly than coniferous needles. Mosses 

 are known to decompose very slowly : but their decomposition 

 once commenced, they pass quickly through the condition of 

 humus to that of complete dissolution. On this account, the 

 living layer 'of moss rests on the ground with hardly any 

 noticeable intermediate layer and may be removed from it 

 like a carpet. 



(b) Soil. The most important factors in the soil, which 

 expedite decomposition of the soil-covering, are, its capacity for 

 heat, its degree of porosity and the amount of moisture it con- 

 tains. Decomposition is generally slowest on clay or loam, 

 quickest on calcareous soil and sand. It is especially rapid on 

 moist calcareous soil in South Germany ; after two years most 

 of the litter is decomposed, the humus decomposing still 

 more quickly. 



(c) Locality. It is well known that decomposition proceeds 

 more slowly on north and east than on south and west aspects ; 

 northerly slopes are damp and cool, and in folds of the hills near 

 the valleys the rate of decomposition is extremely slow ; in such 

 places the greatest amount of partly decomposed humus and 

 litter accumulates. 



(d) Climate. Southern countries prove conclusively that 

 heat combined with moisture is most effective in expediting 

 decomposition ; in South Germany, and still more in Hungary, 

 etc., decomposition proceeds much more rapidly than in North 

 Germany and the countries bordering on the Baltic. Whilst 

 in the latter case 8 or 4 years are often required to complete 

 the process of decomposition, one or at most two years suffice 

 for the former. [In an Indian forest, except in mountainous 

 districts, it is rare to find any noticeable layer of humus in 

 forests. Tr.] The contrasting climates of the lowlands and 

 high mountain-regions of Europe have opposite effects on 



