REGENERATION MEASURES AND THE FORMATION OF SALTPETRE XCIX 
not oxidized into nitric acid, just as little as in the neighbouring 
wood. 
Complete clearings in the spruce forests of upper Norrland, with a raw 
humus covering, belong, as a rule, to this type, but the change of vegetation 
depends very much on the conditions of the ground and other factors. Even 
minor variations in the ground that are not at all prominent when the wood 
is dense, may make themselves very strongly felt on the clearing. 
There are, however, certain parts in the sparse spruce forests with raw 
humus that have a more or less regular tendency to be occupied with a more 
herbulent vegetation. These places are found in the neighbourhood of and 
adjacent to the old stumps, where one often comes across raspberry (Rubus 
zdaeus) and Epitobium angustifolium. This is connected with the influence exer- 
cised by mouldering brushwood and timber on the transformation of nitrogen 
in the ground. 
CHaP. VI. The influence of brushwood and withering timber on the 
transformation of nitrogen in the ground, 
(Detailed description on page 1043.) 
In many of the spruce forests of Norrland, above all within the Silurian 
region of southern Lapland, one can make an observation which may seem 
insignificant in itself, but which, with regard to the question before us, has 
both theoretical and practical interest. On the boundary lines and in small 
gaps one finds a certain break in the somewhat monotonous covering of the 
ground, consisting of mosses and berry shrubs. Raspberry, more or less min- 
gled with Epilobium angustifolium, replaces in patches the normal covering of 
the ground (see fig. 12). If one looks a little closer, one finds that the rasp- 
berry is confined to the neighbourhood of the old stumps, and that they 
thrive especially on those parts of the ground where the spruce 
brushwood was allowed to remain and moulder after the trees had 
been felled. It is therefore this that has produced nitratophilous 
vegetation. | 
In analogy with the observations just mentioned, we sometimes find how old 
mouldering trunks give a nitratophilous turn to the vegetation of the clear- 
ing. In Sösjö Crown Park in Bräcke revir one can thus observe that the 
raspberry plants grow on both sides of old half mouldering trunks while 
the rest of the ground is occupied by Azra fexuosa or berry shrubs. 
Similar observations can be made in central Sweden also. In many of the 
complete clearings in Garpenberg Forests, the present training park of the High 
School of Forestry, Atra flexuosa is the predominant plant in the clearings. 
On the brushwood heaps, however, one finds a nitratophilous vegetation of 
raspberry, Epilohium angustifolium and Galeopsis bifida. Similar observations 
can be made in many other places in our forests. 
These observations show clearly enough that mouldering timber, 
whether composed of old trees, brushwood left behind on felling, 
