120 ENGLISH ESTATE FORESTRY 



of wood, due to a warm and favourable summer, tends to 

 the formation of flower buds, while a spring free from late 

 frosts favours the setting of the flowers and their develop- 

 ment into seed. But, apart from climate, seed production is 

 also encouraged by the crowns of the trees being exposed to 

 sun and air ; and this condition may be brought about by free 

 thinning and comparative isolation of the best trees. Such 

 a thinning is technically known as a " preliminary felling," 

 and consists in taking out about one-half of a full crop of 

 seed-bearing trees. 



A suitable seed-bed consists in a loose and pliable 

 condition of the surface, which allows the seed to sink easily 

 into it, and which provides the seedlings with abundance of 

 plant food when they germinate later on. In thick woods 

 the dead leaves, known as raw humus, are apt to accumulate, 

 and these afford no support to seedlings in themselves, and 

 also prevent them from reaching the more suitable layer 

 below. Time must therefore be given this raw humus to 

 decay, and this can also be effected by thinning out the trees 

 so as to reduce the leaf-fall, and also hasten the decay of 

 previous falls by admitting sun and air. With some species, 

 such as oak or ash, raw humus seldom accumulates, and the 

 surface is usually in a suitable condition for the germination 

 of the seed. In the case of beech, on the other hand, leaves 

 are apt to fall at a faster rate than they decay, and under a 

 heavy crop the surface may be covered by them to too great 

 a depth for successful germination to take place. These 

 conditions must be examined on the spot, and will vary in 

 individual woods ; but enough has been said to indicate their 

 importance. 



A few specific details regarding those species likely to be 

 successfully dealt with by the process in question, namely, 

 oak, ash, beech, and Scots fir, may now be given as 

 follows : 



Oak. Good seed years, with oak, occur on an average 

 about every three or four years, and, as a general rule, no 

 preliminary treatment is necessary unless the trees stand 

 very thickly. The chief obstacle to successful regeneration 

 is the consumption of the acorns by pigeons, pheasants, mice, 

 etc., and it is necessary that they should be covered or 



