REGENERATION MEASURES AND THE FORMATION OF SALTPETRE XCVII 
play a rather subordinate part. Amongst the shrubs may also be noticed 
Pyrola chlorantha. In the woods themselves there appears Viola riviniana, but 
in very isolated specimens. In the wind-caused gaps, even in those of small 
scope, there very soon appears a nitratophilous vegetation, which gives a 
strong saltpetre reaction (see, too, page 1038). These plants also occur on 
ground which has not been disturbed when the trees were blown down by 
winds. 
In the types of forests now described felling has a very distinct influence 
on the transformation of nitrogen in the soil. Either the formation of salt- 
petre is very considerably increased, as in the herbulent spruce 
forest, or else it is produced in ground where formerly nitrifica- 
tion did not take place (e. g. in certain types of mossy coniferous forests). 
This change is independent of all measures taken to prepare the 
Bnonrnd for, a Hew crop he mere increase in theraccess of Helt 
which accompanies ther telling accelerates the formation of sal 
petre (herbulent, sprucemtorests) ot directs the transtotrmnatto mor 
nitrogen into new paths, in that it brings about nitrification (the 
TWOSSyA conIflerousforestsihere desetiibped). 
There are, however, extensive forest lands where the effects of fellings are 
quite different. "These seem to be most extensive in Norrland, but they also 
occur in other parts of the country. 
CHaP. V. Clearings in mossy coniferous forests without 
the appearance of nitrification in the ground. 
(Detailed description on page 1038.) 
The question of the regeneration of the Norrland forests has during the 
last few years been more prominent than ever before in discussions about 
forestry. It has not only become a problem for the practical forester, but it 
has also attained great importance in forest policy when the question of the 
felling of the overmature forests has been closely connected with the ques- 
tion of the regeneration of the ground on which they stand. At first it seems 
to have been hoped that effective regeneration would be obtained merely by 
a select cutting of the timber; but as these hopes have proved to be mistaken, 
the tendency has gradually been to find in complete clearing the right princi- 
ple for the utilization and regeneration of the overmature forests of Norrland. 
The raw humus covering in the Norrland: forests is often fully developed; 
and this is especially the case in the mossy spruce woods which have become 
very sparse owing to select fellings of timber. In these the bilberry shrubs 
have attained a high degree of development, especially in the somewhat lighter 
parts between the trees, while the red whortleberry shrub is usually predominant 
immediately under the crowns of the trees. The thimber felling here seems 
often to have brought about conditions extremely favourable for the bilberry 
shrub; and as that shrub is a powerfubk former of raw humus, this form of 
cutting has also favoured the development of a great raw humus covering. 
We may refer to figs. 8 and 9 for an example of the shape this can take 
in a fairly old, extremely sparse spruce forest with weak powers of growth. 
Under the covering of living moss we find a very thick and strong layer of 
half-mouldered moss remains, penetrated by the underground branches of the 
VIL.  Meddel. från Statens Skogsförsöksanstalt. 
