18 BULLETIN 1163, U. S. DEPARTMENT OF AGRICULTURE. 
to cut stands before there is any real loss and at the same time per¬ 
mit the trees to attain the maximum size. 
Equally important is the periodic rate of increase in the loss through 
decay after the above age has been passed. Such information is of 
the highest value to organizations holding extensive stands of mature 
or overmature timber, enabling them to estimate the loss in their 
holdings and adapt plans accordingly. But these questions can only 
be answered by the study of all the trees felled and left standing on 
a wide range of plats in stands of different ages and conditions 
selected on logging operations throughout the Douglas-fir region of 
the Pacific Northwest. 
