146 OUR FORESTS AND WOODLANDS 



average annual growth in height reaches about 

 fifteen inches on favourable situations, and even 

 increases to about nineteen inches among the 

 predominant poles of twenty to thirty years of 

 age. On soils of a less favourable character the 

 growth is of course less, while it does not reach 

 its maximum till from ten to fifteen years later. 

 The thick fall of leaves, rich in potash, yields the 

 finest class of woodland mould, so that at this 

 stage of growth dense thickets of beech enrich 

 and improve the soil in a greater degree than any 

 other crop can. Stimulated thereby, the growth 

 in cubic contents proceeds so vigorously that 

 pure beech highwoods, on soils of only average 

 quality, yield over 8000 cubic feet (true measure- 

 ment) per acre; but, unfortunately, only from 10 

 to 20 per cent, of this is usually classifiable as 

 first-class timber, the bulk of it being too small 

 for reckoning as such. 



