ECONOMIC VALUE OF FOREST FLORA 195 



tions in this country are few, and much depends upon the 

 surface conditions at, or immediately after, the sowing. 

 Scots pine is successfully sown on sandy soil in 

 German}', spruce in Bavaria, silver fir in the mountain 

 districts of Central Europe, maritime pine in Gascony, 

 etc. In Britain, however, sowing of conifers has rarely 

 been a success when tried, but the cause of failure is not 

 easy to explain. On thick grassy surfaces the seedlings 

 of most small seeds have little chance in any case ; but it 

 is possible that slugs and birds are the two chief causes 

 of failure, combined with the ease with Avhich conifer 

 seedlings are killed by drought during the first summer, 

 or thrown out by frost during the first winter. On 

 peaty soils, however, sowing would probably prove a 

 success in many cases, but here again trouble from frost- 

 lifting is general in Britain, whereas on the Continent a 

 thick snow covering usually protects them in winter. 



Several broad-leaved species, such as oak, chestnut, etc., 

 can however be sown in situ Avith little trouble, provided 

 protection against such animals as mice, pheasants, etc., 

 is given them. A century or so ago sowing was the usual 

 method practised with these species, but for several 

 reasons, the chief probably being the great quantity of 

 seed required per acre, the custom has been discontinued. 



Natural regeneration very largely depends upon a num- 

 ber of factors which are rarely found in combination on a 

 large scale, or over a large area. Many of these factors 

 are connected with surface conditions, depending upon 

 various forms of vegetation either resulting from soil, 

 situation, or artificial interference with the timber crop. 

 Others are closely connected with climate, and especially 

 rainfall, which latter may enable seed to germinate, and 

 the plants to survive under surface conditions which would 

 otherwise prove fatal to them. 



Amongst the common species, beech, ash, sycamore, 



