TIMBER GROWING IN DOUGLAS FIR REGION Ti 
reproducing logged-off lands, therefore, whether it be an all-killing 
fire or not, should be regarded as damaging ‘ to the welfare of the forest. 
The season of the year at which slash burning should be done is of 
' considerable moment, not only because of the effect upon reproduction 
but because of the relative difficulty of handling fire in the spring and 
in the fall. 
Spring slash fires consume less of the deeper layer of duif and humus 
than do fall fires. Consequently more of the seed of the last and 
earlier seed crops might be expected to survive spring fires than fall 
fires. On the other hand spring burning has some practical dis- 
advantages. Spring fires leave unburned more ma aterial to invite a 
later fire than do fall fires. Spring burning, also, is risky unless 
the operator is willing and prepared to put out every smoldering fire 
before the dry season, in case late spring rains do not do so. 
There are difficulties and disadvantages in burning at any season, 
and the operator must compare all the advantages and all the dis- 
advantages from every angle for each particular set of conditions. 
It is obvious that slash burning, both in the spring and fall, gives a 
semiannual clean-up which is better from the fire-protection stand- 
point than doing all the burning only once a year. This, together 
with the very positive advantages to reforestation of prompt burn- 
ing, point to the wisdom of a “‘burn as you go”’ policy; 1. e., burning 
small areas of fresh slash as fast as they accumulate, using both the 
pane and the fall and even the winter season, as circumstances may 
allow. 
THE PLACE OF SINGLE SEED TREES IN DOUGLAS FIR REFORESTATION 
It has been shown above that the splendid reproduction which 
characterizes much logged-off land in the Douglas fir region comes 
chiefly either from seed cast by the virgin forest before logging or that 
blown in from adjoining blocks of uncut timber. Where a large area 
is logged absolutely clean, there is no other source of seed. 
In some logging operations it 1s the practice to leave here and there 
single trees which are too defective to be worth logging. This was 
formerly much more common than it is now. On the national 
forests 1t is the standard practice to leave an average of about two 
seed trees to the acre, usually misshapen or conky trees. 
In some parts of the Douglas fir region it is not uncommon to find 
an average of two or three big conky trees per acre of which the 
merchantable value is little or nothing, yet which have a potential 
value as seed trees if left intact. The effect of such trees in assuring 
adequate seeding up of their environs is very important. There 
are other parts of the Douglas fir region where the timber is so sound 
that no seed tree can be left without a sacrifice of commercial 
stumpage. 
Any trees of seed- producing character that can survive contribute 
toward the reforestation of the land and are particularly useful if 
an accidental fire wipes out the initial crop of seedlings. The smaller 
trees of a stand, which might by chance be left, do not function very 
well as seed trees because they are quite likely to be knocked down 
by the falling of their larger neighbors, to be killed by the slash fire, 
or to fail to produce seed. Even some of the larger trees may be 
killed by the slash fire, principally from heat damage to foliage . 
rather than to the living tissues of the trunk. 
