12 



. Next to soil fertility and moisture the factor that most 



determines tree growth is the amount of sunlight af- 

 forded All trees grow most rapidly in the full sunlight; yet each 

 species has its peculiar requirements. A species that thrives with 

 little sun is tolerant of shade, or commonly simply "tolerant" sugar 

 maple, spruce: one that requires full sunlight is intolerant pitch 

 pine, gray birch. There are all degrees between the extremes, 

 though young trees of any species are more tolerant than old ones. 

 It is this quality of tolerance, or light requirement, that determines 

 whether trees make the tall clear shafts that produce the most valu- 

 able lumber, or whether they grow short and branchy as a shade 

 tree should. It is also one of the forester's chief aids, since by tak- 

 ing it into account nature will help produce the desired results. 



Know Of course, one must know the trees what are the 



the Trees. characteristics of oaks, of maples, of pines, etc. 

 Whether or not one gets any knowledge of silviculture, it is a pleas- 

 ure to be able to identify any tree at sight. This can be done in a 

 comparatively short time by carrying a tiee book and studying each 

 tree on the spot. The best for this purpose are references n, 12, 13. 



References i, 2, 5, 6, 7, n, 12, 13. 



I. In a mixed forest what kinds of trees have the 

 Questions. , , . 



best chance to grow? 



2. On sandy land of low fertility what kinds of trees will be 

 apt to thrive best? 



3. How does sunlight affect the relative vigor of forest trees? 



4. How can any one tree in a forest be given an advantage 

 over its neighbors? 



5. How can the age of a tree be told? 



6. Are trees of the same kind and same size always of the same 

 age ? Why ? 



FOREST PLANTING. 



Forest planting must not be confused with tree planting, for like 

 forestry in general it deals with masses, not with individuals. More 

 t*ees always are planted than are expected to mature. 



