AMERICAN SYLVICULTURE 



brilliant white clouds. Leaf cover overhead is favorable when it 

 filters the rays of a burning sun and unfavorable when it excessively 

 reduces the intensity of insolation. Under a continental climate, 

 •cloudless days are more numerous than near the coast. The influ- 

 ence of thinnings and removal cuttings on the remaining growth, 

 consequently, depends on the continental position of a forest, — not 

 solely on species and soil. 



X. The regeneration of forests approaching exploitable age 

 is easiest in their optimum climate. If the climate is too warm, 

 seed will be more abundant, and the young plants will endure cover 

 better. The moisture of the air, however, is wanting, and the 

 denser cover overhead may intercept too much of the needed rain- 

 fall. 



If the climate is too cold, the moisture of the air indeed 

 increases; but the production of seeds and the persistence under 

 ■cover decrease. 



Y. In mixed forests, artificial regeneration is more difli- 

 •cult than natural regeneration. A clean felling results in a capri- 

 cious complication of natural laws and phenomena whose contrary 

 actions are not easily understood. Natural regeneration, a mixture 

 of species suitable to the locality, a crop resembling as closely as 

 possible the primitive state, such are the conditions which the 

 forester should seek to realize for the avoidance of dangers as well 

 as for the greatest possible yield of the most valuable produce. No 

 method of treatment harmonizes better with nature's laws than 

 the so-called selection system, when each tree is placed in a con- 

 dition most favorable to its development, and when no single tree 

 is removed for a purpose other than that of regeneration or im- 

 provement of the crop. 



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