THE ART OF THE SECOND GROWTH 



P. The moister the climate, the easier becomes forest cul- 

 ture, and the forester is apt to make the least mistakes in thin- 

 nings, regeneration fellings, etc. Air moisture seems to exercise a 

 favorable influence on the straightness of tlie stems. 



Q. A failure of rain for several days may be fatal 



to young plants. The faculty of persistence increases with age,. 

 and the grown trees can endure long periods of drought. If, 

 however, the lack of rain is such as to bring the sum total of 

 precipitations during the four months of the growing season below 

 the two-inch mark, then the forest disappears, even if the humidity 

 of the air remains above .507o- Exception: Immediate neighbor- 

 hood of lakes and rivers with their sub-soil percolation. 



R. A fairly moist soil is the best for all species in 

 tJieir optimum climate. In hotter places the locality must be more 

 damp, while in colder ones it may be dry without hindering growth. 

 (White Pine in the Southern Appalachians in swamps, in Canada on 

 dry soil; Sitka Spruce in Washington on wet laud; In Alaska on 

 dry land). 



S. Snow protects those parts of a plant which it covers; 

 it increases the danger, however, for the parts just above the snow- 

 level. Snowy winters are, therefore, useful to low plants, but 

 harmful to trees. 



T. As regards the trinds, the most dangerous are those 

 following the direction of the barometric minima, w^hich travel in 

 North America and in Europe from west to east; in East Asia 

 from south to north. Next dangerous are the winds traveling in 

 the opposite direction, whilst those from other points of the com- 

 pass are more harmless. Every mountain, however, creates a de- 

 flection of the current and possibly a return in the opposite 

 direction. 



U. In their youth, the trees are almost indifferent to the 

 quality of tlie soil; with increasing age their exigencies increase. 

 Thus plantations on poor soil may thrive well for a number of 

 years, to be suddenly arrested at the beginning of the pole stage. 



V. In their most suitable situation (natural optimum) a 

 species succeeds on soil of any mineral description. Ih a less favor- 

 able climate the soil requirements of tlie species increase. 



W. The light most favorable to activity of the chlorophyl 

 is not the light of the blazing sun, nor is it the diffused light 

 coming through rain or fog, but that liglit which is reflected by 

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