314 CONIFEROUS FORMATIONS SECT, xv 



In northern parts of Europe the relations are often somewhat 

 different. The soil is occupied by xerophytic dwarf -shrubs belonging to 

 pine-forest ; an underwood of SaHx, Betula, Alnus, Sambucus nigra, and 

 others may develop ; while lichens are present, though scanty. 



There are, therefore, different varieties of spruce-forest, which differ 

 in the nature of the ground- vegetation, according as mosses, grasses, 

 perennial herbs, and so forth are abundant. 



Spruce-forest retains humidity more efficiently than pine-forest does. 

 Raw humus occurs not infrequently in spruce-forest ; the carpet of 

 spruce-needles covering the ground may be interlaced by fine spruce- 

 roots and produce peat, beneath which hard pan occurs, just as in ling- 

 heath or beech-forest. Raw humus produced from spruce is lighter in 

 colour and less firm than that derived from Calluna or beech. 1 



Common spruce produces prostrate branches, which often trail over 

 considerable distances, and may produce adventitious roots as well as 

 new leading shoots. In this way the spruce can acquire several stems 

 and give rise to scrub. 2 In this respect it goes farther than the Scots pine ; 

 for the latter retains the tree-form until external conditions prevent its 

 growth, whereas the spruce assumes deformed and prostrate shapes, not 

 only when it passes beyond the limit of forest in Lapland, 3 but also on 

 the shores of Norway. 



Silver Fir Forest. 



Abies pectinata, the common silver fir, is a conifer producing vast 

 and stately forests in the central and southern mountainous districts of 

 Europe. In the mountainous parts of Saxony (' Saxon Switzerland ') it 

 competes with Picea excelsa ; on the poorer sandstone, which weathers 

 with difficulty, Picea has the upper hand, but on the basalt, with its 

 thicker weathered strata, Abies dominates. Yet both species may occur 

 on the two kinds of soil, and the final issue is the result of their struggle. 4 



Mountain-Pine Woodlands. 



Pinus montana gives rise to stately forests in the Pyrenees and French 

 Alps, but farther east it dwindles to scrub (elfin wood = 'Krummholz'), 

 and, expelled from more favoured localities by other species, has to 

 content itself with the poorest habitats. 5 It is a shade-enduring tree, 

 though not to the same extent as the Norway spruce, 6 so that in its forests 

 the ground is poor in plants. 



Pinus montana grows not only on the driest and most sterile mountain- 

 slopes, but also in wet moor, and in both these situations it gives rise to 

 scrub or bush-forest. 7 Beneath it on moors grow such shrubs as Ledum 

 palustre, Andromeda polifolia, Calluna, Vaccinium uliginosum, V. Myrtil- 

 lus, Vaccinium Vitis-idaea, V. Oxycoccos, also such low herbs as Erio- 

 phorum and Carex, mosses such as Hylocomium, Dicranum, and Sphag- 

 num, and, finally, lichens. In fact we are dealing with a Calluna-moor* 



1 P. E. Muller, 18870; Ramann, 1905. 2 J. M. Norman, 1894-1901. 



3 Kihlman, 1890; and see p. 215. 



4 P. E. Muller, 1871 ; Schroter, 1904-8. * See p. 18. 



P. E. Muller, 1887 b. 7 See p. 216. * See Chap. LII. 



