50 WESTERN YELLOW PINE IN ARIZONA AND NEW MEXICO. 
It often happens that some dry-topped and diseased trees which 
can and should be removed are overlooked in the original marking. 
It may also be advisable to reserve seed trees that were originally 
marked. Necessary changes in the first marking should be made 
before the sawyers have moved away. It is only by a careful re- 
marking that undesirable trees can be completely eliminated and 
necessary seed trees retained. 
In marking timber a simple rule to remember is: Mark most yel- 
low pine and leave all healthy blackjack except when in need of 
thinning. This rule should be varied according to the age and con- 
dition of the stand marked. If the timber is mature, with no repro- 
duction, it may be necessary to retain trees that are fully mature, and 
approximately one-third of the volume may have to be left standing, 
even at some risk of windfall and decline in vigor. In a mature 
stand with good reproduction the marking may be heavier, but suf- 
ficient trees should be left to provide for reproduction in case of 
fire. The marking should aim to open up the reproduction and 
enable each group to enlarge. It should also tend to improve the 
stand by removing dry-topped or otherwise deteriorating trees. Ina 
pole stand of blackjack thinning can often be made to advantage, 
but these should never be heavy and should aim to preserve a close 
canopy. Trees which should be removed are those that are deterio- 
rating and which may be eventually suppressed. 
In marking any sale area innumerable variations will be encoun- 
tered, and no uniform system should be adopted for the entire stand. 
On the border of the woodland type the marking should be merely 
an improvement cutting, and if the stand is less than 2,000 feet per 
acre no cutting whatever should be allowed, except the occasional 
removal of dying trees, and this only if practicable from a lumber- 
man’s standpoint. On the borders of parks and where windfall is 
likely, or where it is desirable to preserve forest conditions, marking 
should be particularly conservative. On dry south slopes and on 
ridge crests but a few trees should be removed. Ordinarily in west- 
ern yellow pine an approximate diameter limit of 20 inches should 
be stated, though not followed lterally in the marking, as already 
explained. Wherever practicable advantage should be taken of good 
seed years to increase the cut or to direct the marking where the local 
seed crop is best. The scenic value of timber along roads must be 
carefully weighed. 
Table 28 shows the actual results of marking on a large timber sale 
area in the Coconino National Forest. Figures are given for each 
section, in order to show how uniform the cutting has been. The 
windfall on seven sections was; respectively, 0.7 per cent, 0.2 per cent, 
0.6 per cent, 0.2 per cent, 0.8 per cent, 0.3 per cent, and 0.8 per cent of 
the stand from one to two years after cutting. This loss was almost 



