SUITED FOR PLANTI^'G. 301 



beeches, and occasionally produces a fine stem, [e.g. Eotlienkir- 

 cliener Forstrevier, Forstorte Uhlenstocke, Ahlsburg, Fuclisloclier, 

 and Hanebach) ; on the lighter-coloured, poorer varieties it does 

 not thrive so well, but is useful underwood for improving the 

 .soil. 



III. The Relations between Soils and Subsoils, and their 



effeets on Timber. 



In the preceding pages we have directed attention almost 

 solely to the soils suitable for the various hardwoods reared in 

 forests ; now we examine shortly the relations between soils and 

 subsoils, and the combined effect they produce on the timber 

 reared over them. Where the soil is dry, or apt to be rendered 

 dry by the sun's rays, the subsoil must be moist and capable of 

 supplying the roots of the trees with a sufficient quantity of 

 moisture for their nourishment. If it have a disposition to 

 become wet, an undersoil which can absorb and retain a large 

 quantity of moisture is highly desirable. The underlying layers 

 may be of the same rock, whence has arisen tlie soil by decom- 

 position, or of a different nature — it may be impervious, or cleft, 

 horizontal, inclined, or tilted. An impervious subsoil is never 

 desirable, and ought to be broken through before sowing or 

 planting operations are commenced. A cleft undersoil may in 

 some cases be extremely useful, in others it woi'ks deleteriously. 

 Thus, if a wet peat, or marsh, or a still clay apt to become 

 saturated with rainwater, and so give rise to swampy, marshy 

 ground, be above, a cleft subsoil works most beneficially in con- 

 ducting away a large quantity of the superfluous moisture, and in 

 rendering it less tenacious and plastic ; imperfectly decomposed 

 organic remains in the peat have then a better chance of being acted 

 on by the atmosphere. Again, if the under-soil be much cleft, an 

 immoderate supply of moisture is drawn from the surface-soil, 

 and conducted far down into the rock, in consequence of which, 

 (as may be well seen in the case of Norway spruces (Picea, 

 excelsa), in many parts of the Eisenacher Forst, the trees 

 remain dwarf, the material that ought to increase the stem, in 

 height and girth, being employed in the formation of roots, 

 which, spreading far and wide in search of moisture, are strangely 

 disproi^ortionate to the size of the tree. 



Horizontal layers are apt to collect an over-supply of moisture, 

 on account of which the quality of the timber is injured; this 

 evil is, however, not by any means so observable where the soil 

 is deep, loose, and therefore inclined to be dry. If it be shallow, 

 wet, or plastic, an inclined or tilted underlayer is more favourable 

 to the growth of timber. 



Massive rocks, such as granite, diabase, basalt, porphyry, &e., 

 are generally but moderately cleft, remain moist, and form good 

 under-soils; many clays are, however, plastic and impervious, so 



