CXVIIL HENRIK HESSELMAN. 
bound up with both the planning and the treatment of the regrowth areas, and 
also with the previous management of the forest. To begin with, I wish to 
dwell on the latter of these two questions. 
The woods which are most favourable for the natural regeneration of the 
forest are represented by the type which we meet with in central Sweden-— 
such as the forests of Jönåker, Högsjö, Äs and Alkvättern. The ground- 
covering consists, in the main, of a mossy carpet, the raw humus layer is 
rather loose and mellow and of a very moderate depth (see fig. 4). Berry- 
shrubs and heather play a quite subordinate part in its production, What 
really forms the humus is the mosses and fallen boughs and fallen needles 
from the trees. Even the opening up of a little gap produces an active nitri- 
fication; yet the herb and grass vegetation will not become excessively luxuriant, 
but the pine and spruce plants can germinate comparatively easily, and, provided 
they come by sufficient light, develop further (see figs. 5, 34, and 41). 
The opposite type is represented by woods where the raw humus covering 
has attained a very strong development. This is often the case in the sparse 
spruce forests of Norrland. There, under the carpet of moss, we have 
a more or less thick layer of half-mouldered moss remains, woven together 
with stems of berry-shrubs and the like. Mosses and berry-shrubs are here 
the most important humus-formers. If a sufficient amount of light is ad- 
mitted to the ground in such a stand, Azra flexuosa develops and soon forms 
a thick carpet, which is not very susceptible of the germinating coniferous seed. 
The humus nitrogen is not converted into saltpetre, at least not in any quan- 
tities worth mentioning; and planted plants develope distinetly worse than 
in places where the humus nitrogen is nitrified. 
The above-named mixed coniferous forests in central Sweden, which are 
highly productive and suitable for regeneration, are distinguished by their great 
denseness, and the ground under the trees is pretty evenly overshaded. This 
has undoubtedly a very favourable influence on the humus-covering; but for 
the present I will say nothing on the question whether this is the only cause 
why it changes so rapidly and so advantageously for regeneration on the trees 
being cut. No analyses of the mineral qualities of the ground have yet been 
made. The ground flora in the wood, however, does not indicate a specially 
fertile forest soil; in the ground-covering the same species are met with as 
in woods with strong raw humus; but the proportion between the various 
species is different, and the mouldering of the plant-remains proceeds in a 
different manner. 
In the development of an unfavourable raw humus covering both the climate 
and the ground, and also the treatment of the wood, are of great import- 
ance. The rawer and colder the climate is, the more easily does the humus- 
covering acquire a character unfavourable to the forest; but the treatment of 
the wood itself obviously plays a very great part. In the extremely sparse 
old spruce forests, where the access of light is stronger than in a really dense 
spruce forest, but where it is too weak to produce a very active transforma- 
tion, berry-shrubs thrive well and contribute powerfully to an unfavourable 
development of the humus-covering. In the low-lying parts of Norrland, that 
is to say, near the coast, where the climate is most favourable, the clearings 
show a greater degree of transformation in the humus-covering. Nitratophilous 
plants are not so very rare there, even if the ground has not been burnt—for 
