1 14 Studies in Forestry [CHAP. v. 



the danger from frosts is greater in hollows and throughout 

 low-lying tracts than where currents of air have free play. 



Mountain masses have greater uniformity of soil and situation 

 than ranges of hills. On these the well-being of the woodland 

 growth depends to a great extent on the amount of protection 

 that can be given to it from winds ; for the bad effects of want 

 of protection may only too clearly be seen in exposed planta- 

 tions or woods near the sea-coast or on bleak hill-sides. 



In the assessment of the quality of soil the best standard is 

 that which makes five distinctions, thus : 



I. Very good ; II. good; III. average or moderate; IV. inferior; 

 V. poor. 



In Germany the decimal system is often adopted. But 

 practical men will have less difficulty in making up their minds 

 as to whether any given soil is average or inferior in quality, 

 than they will find in estimating it at 0*3, or 0*4, or 0*5 of the 

 first-class soil classed as equivalent to i 'o. Such assessments 

 are very useful, but are in each case only relative ; for a soil 

 that might only be regarded as inferior so far as the cultivation 

 of mixed crops of Oak, Maple, Sycamore, Larch, Douglas Fir, 

 and Beech are concerned, might perhaps be considered a 

 moderately good, or even a good soil if considered with regard 

 to woods in which Pines, Spruces, and Firs were to be the 

 ruling kinds of trees. 



