HOW BIG TREES GROW 49 
After forty years the mad race rather slows down. 
The period of most rapid height growth has passed and 
the three hundred or four hundred trees now forming 
the stand, tall and rather slim with crowns completely 
shading the ground are the picked survivors of the 
10,000 that started and each is nearly as strong as his 
fellow. From now on.they commence to take on girth 
like boys who suddenly change from gangling youths 
to sturdy young men. Good wide rings are laid around 
the trunks, covering up the places where branches 
formerly pushed through the bark. This means clear 
timber free from knots and easy to work, the kind that 
delights the carpenter or the pattern maker. 
From now on our forest community loses a citizen 
from time to time, from lightning stroke, disease, in- 
sects, etc. The holes in the canopy are soon filled by 
the neighboring crowns which still possess the power 
of vigorous growth. The trees are now reaching 
maturity with tall cylindrical boles, having from fifty 
to sixty feet of clear length since the crown has been 
continually shortening. Finally a time comes when 
the crowns can no longer fill the gaps and the opening 
made by a fallen veteran remains open and permits the 
sunlight to reach the ground beneath the trees. The 
forest floor previously shaded and free from weeds now 
shows patches of grass here and there, the thick layer 
of humus begins to decompose under the influence of 
sunlight and the forest as a whole is ready to reproduce 
itself beneath its own shade. This period, known as 
‘‘silvicultural maturity,’’ occurs some time before the 
final breaking up of the old stand but nevertheless it 
marks the beginning of the end. 
From now on the decline is quite rapid as measured in 
forest periods. The groups of seedlings found beneath 
