ot PRACTICAL FORESTRY 
assemblage of trees, and his unit is at least a small 
group or hurst. For example, let us imagine an acre 
of land over which we have sown the seeds of pine. 
Let us imagine that these have germinated and grown 
so that the crown of every little tree has met the 
crowns of its neighbors. The thicker the trees the 
sooner will the branches of their crowns interlace, 
and there is then formed a canopy. As the little 
trees grow, there is a struggle for room. The weak- 
lings are unable to hold their own. The strongest 
push upward into the air in quest of light and room. 
Soon there are those which are dominant, and those 
which are suppressed and dying. The forester, by a 
careful system of thinning, endeavors to maintain a 
uniform canopy, so that it will rise in a zone grad- 
ually higher each year as growth proceeds. The 
density of the canopy is so carefully regulated that 
the number of trees in the forest is in due proportion 
to their size, so that the quality and quantity of wood 
are always in the highest degree. In order to produce 
a fine quality of wood, the shade must be regulated so 
that the lower branches are shed while still small in 
size as the canopy moves upward with the height 
growth of the trees. The ideal canopy is an unbroken 
whole—in fact, the forest on the acre referred to is 
not unlike one great wide-spreading banyan tree with 
hundreds of trunks, In a rough, irregular forest there 
