THE LARCH AND ITS IMPORTANCE IN SWEDISH FOREST ECONOMY. LXXlI 
Institute of Experimental Forestry show that this is also the case with the 
larch. In this connection, however, it is of importance that the kind of tree 
mixed with the larch should not greatly overshadow the larches. From this 
point of view, the spruce is risky in certain cases, when it reaches the first 
tree-stratum, that is to say on better lands. If the spruce is keptas an inter- 
mediate stand —-- second and third tree-strata — the mixture is less dangerous 
from the standpoint of light. If, on the other hand, the spruce occurs only 
as undergrowth, the larch would be more to be regarded as pure stand and 
the possible advantage of mixture would become illusory. 
The mixing with pine, on the other hand, can be unreservedly recom- 
mended. The sample plots provide many examples of successful mixtures of 
this sort which are little affected by canker. 
In order to avoid larch-canker, moreover, the larch should not be culti- 
vated in moist low-lying places. This partly in order that it shall not be 
exposed to injury by frost, through which the canker may spread, and partly 
because the larch-fungus develops freely in raw, damp positions. The same 
reasons speak against using the moist places in Sweden with a heavv preci- 
pitation. In central Europe it is considered that the larch should not be 
cultivated where the average rainfall exceeds 600 mm. In Sweden too, in 
the south-west of Sweden, with a rainfall of about 700 mm., its cultivation 
has proved rather doubtful, with the exception of the Scottish race, which 
seems able to thrive both there and on the west coast of Norway. 
These points go to show that there are many possibilities of avoiding the 
rapid spread of the larch-canker; but it is certain that scarcely anything of 
that kind has been done here in Sweden. In laying out larch woods there 
has been no thought of avoiding larch-canker, but many stands have been 
raised hap-hazard (it is more or less by chance that it has been done with 
a mixture of pine in many places), and then, when the canker has made its 
appearance, the cultivation of the larch has been sweepingly condemned. If, 
however, more care is taken to adopt suitable forms of mixture for the larch, 
and if larch stands are afterwards subjected to heavy thinnings, it is the 
decided opinion of the present writer that, in the greater part of Sweden, 
the larch-canker will not be a very dangerous disease. 
Finally, on pp. 690—9691, there is a brief mention of other species of 
fungus that attack the larch, but are of minor economic importance. 
Chap. III G treats the properties and use of larch timber. 
No direct investigations into larch timber etc. have been undertaken, as 
there is no equipment for such technological investigations at the State Insti- 
tute. In Table 13 there is a comparison, based on JANKA's investigations 
(544 6), between the lumber properties of the larch, the pine, and the spruce. 
It is above all things the great percentage of heartwood in the larch that 
makes this timber so excellent. Thus this seventy-year-old larch-stand of 
quality I has a heartwood mass amounting to 50.7 Y, of the whole trunk 
mass, and 62 HY, of the trunk timber without bark. An example of the extent 
of the heartwood is shown in Fig. 74, where a trunk analysis from that stand 
is given. 
The formation of heartwood also begins very early. A fourteen-year-old 
stand of Siberian larch at Omberg (sample plot 283) was found to have at 
the root a heart of 39.6 of the stump diameter on an average. A material 
