TIMBER GROWING AND LOGGING PRACTICE IN CALIFORNIA 67 
DISTRIBUTION OF SEED TREES 
The distribution of seed trees is of fundamental importance. If 
the production of full timber crops is desired, no mechanical method 
of selectin^^ the trees or of spacing them is generally applicable. 
Obviously the statement that three seed trees per acre are needed 
does not imply that this number will appear on each acre. The 
virgin forest is so variable that in following out the principles here 
laid down it is often necessary to make openings of 2 or even 3 acres 
in extent, simply because there are no suitable trees to leave. An occa- 
sional opening of 3 acres is not to be regarded too seriously, par- 
ticularly if there are seed trees around the edges. For any extensive 
area, howcA^er, an average of three trees per acre should be left. 
SELECTION OF TREES TO LEAVE FOR GROWTH 
Full timber-crop production does not stop with the selection of 
three healthy seed trees to the acre. It demands as well the reserva- 
tion of other thrifty trees capable of rapid growth after release by 
cutting. Such trees will be the basis for the second cut, and their 
selection is the key step distinguishing this type of forest cultiva- 
tion from the measures previously discussed. 
Trees of certain characteristics make rapid growth after release by 
cutting, and others have no marked capacity for profitable growth. 
In general, young trees are thrifty ; old trees are growing so slowly 
that though they may respond to cutting the rate of growth is still 
veiy low. The external physical marks of youth are; first, the bark, 
which, particularly in the pine, is dark in color and broken into finer 
corrugations than on old trees; second, form and shape of crown. 
Uninjured young trees have conical pointed crowns, the unfailing 
indication that height growth is in progi;ess. Usually young trees 
have long crowns, i. e., more than half the total height of the trees. 
Lumbermen recognize that the young trees, variously called " black- 
jack" or "bull" pine, yield a poorer quality of lumber than is 
obtained from the mature or " yellow " pines. Thus, saving j^oung 
trees for growth and for seeding may not affect seriously the profit- 
ability of the logging operation. 
Flat or rounded tops, especially the former, are the unfailing 
indices of old age, and show that height growth has ceased or is at 
a very low ebb. Cessation of height growth is correlated with great 
reduction in the rate of diameter growth and with loss of ability 
to attain a profitable acceleration in growth rate after release. 
Therefore, the primary rule in selecting trees to leave for growth is 
to reserve healthy trees of "blackjack" characteristics and to cut 
" yellow " pines. With the other important species, similar practices 
should be adopted, cutting the old and leaving the thrifty young 
trees. 
INCREASED GROWTH ON RESERVED TREES AFTER CUTTING 
By careful selection of trees to remain uncut, rapid and profitable 
formation of w^ood can be obtained. This is one of the important 
sources of value of properly logged lands, and is largely or entirely 
lost through unregulated logging. 
The rate of increase of growth after cutting varies greatly, de- 
pending on the amount of cutting close to the trees left, the char- 
acter of the reserved trees, and the quality of the land. 
