54 FORESTRY 



The first two of these conditions are secured by a series 

 of thinnings of increasing severity being carried out in the 

 old woods. There results an accession of light and warmth 

 which favours both the production of seed and the decom- 

 position of the vegetable matter covering the soil. Without 

 preparatory treatment the thick layer of humus that collects 

 under the dense shade of a close crop may prove too much 

 for the tender radicles of seedlings to penetrate, and unless 

 they can reach the mineral or true soil, the. embryo plants 

 die as soon as they have exhausted the nourishment stored 

 in the seed. 



The age of the wood which it is proposed to fell and re- 

 generate has also to be taken into consideration. Immature 

 woods supply no fertile seed, or an insufficient quantity of 

 it, while very old trees get past their best for seed pro- 

 duction. Moreover, the ground below such old woods is 

 apt to become dry, overgrown with weeds, and otherwise 

 unfit, not only for the reception of the seed, but also for the 

 development of the young plants. The limits of age within 

 which the natural regeneration of our common forest trees 

 is most certain to be successful, lie between eighty and one 

 hundred years, or even a greater age in the case of Oak. 



In an ordinarily dense wood where only moderate thinnings 

 have been carried out, the process leading to reproduction is 

 commenced by a preparatory cutting ; about one-fifth to one- 

 quarter of the trees are taken, the removed material con- 

 sisting chiefly of the smaller stems from which good seed 

 cannot be expected. 



The new crop is then obtained by means of a "seed- 

 felling," which so far reduces the number of the existing 

 older trees that seedlings are able to spring up and establish 

 themselves. This cutting should, however, preserve for the 

 young plants enough of the old wood to act as shelter from 

 frost and drought. It should remove about one-quarter to 

 one-third of the existing wood, the -largest trees being those 

 that are felled. The overhead shade ought to be better main- 

 tained where, as on limy soils, a strong growth of grass and 



