46 BULLETIN 308, U. S. DEPARTMENT OF AGRICULTURE. 
good root systems so as to be windfirm. Such trees may not occur 
naturally in the stand. In this case it is advisable to make the last 
thinning in such a manner as to develop from 4 to 10 good seed 
trees per acre, well distributed over the area. The number will 
depend upon the age and size of the trees, more being left on eleva- 
tions than elsewhere. In the case of long-stemmed, slender trees, 
groups of two to four serve the purpose better than single trees. 
At least an average of three of these small groups should be selected 
for each acre. The crowns of the individual trees or groups as a 
whole should be entirely freed on all sides by the last thinning. Due 
allowance should be made for old “ forest ” or “ heart ” pine trees that 
may be left along fence rows or along the margin of a stand. These 
are usually heavy seed producers. It is essential to mark the good 
seed-producing trees in advance of logging. Blazing or boxing is 
injurious and should be strictly avoided. Some simple method, such 
as the use of strips of old sacking or burlap, is effective and inex- 
pensive. Light hacking in the outer bark only, if done carefully on 
two sides of the tree, is one method of identifying the trees against 
cutting. All other merchantable trees may be cut, but if the stand - 
is younger than about 35 years many of the small-sized lower crown 
classes will recover if left after logging. In most stands there are 
shade-enduring hardwoods, such as persimmon, sassafras, and dog- 
wood, which have entered small openings in the pine. It is desir- 
able to cut these in order to prevent their developing later and 
overshading the pine saplings. | 
In unthinned, well-stocked stands good seed trees are not usually 
developed until the maximum height growth is passed and crown iso- 
lation begins to take place, which is at about 40 or 50 years. There 
are present also many trees of the lower sizes, too small to saw into 
lumber without a high degree of waste. In such cases the large trees 
may be logged in a first cutting and the operation repeated after an 
interval of 5 to 10 years. Groups of seedlings will establish them- 
selves in the successive openings thus left. The remainder of the 
stand, previously thinned at the time of the second cut, may be re- 
moved in a third cutting as soon as a thorough restocking is assured, 
or they may be held over to form large standards for cutting during 
the first thinning of the younger stand. In understocked stands a 
larger per cent of the trees are of a merchantable size and can be 
taken in the first cut. Seed trees are developed from the smaller 
trees, which are of less value for saw timber and show rapid develop- 
ment in crown spread and seed production through an increased 
light supply. 
The second method (strip method) leaves alternate strips of clear- 
cut land and standing timber. The openings may be as wide as four 
times the average height of the trees and the timber strips one-fourth 
