20 TREES IN" WINTER 



factors and how do they become effective? What influence do they 

 have upon the growth .of the individual tree? 



If a wood& is cut do^A^l or burned over or if a pasture is neg- 

 lected^ what are the first trees most likely to grow up? How have 

 they come there? Are these the trees that will prevail after fifty or 

 one hundred years? What is the character of the '^climax forests" 

 in the region investigated? In the northeastern part of the United 

 States there is no lack of deserted pastures in all stages of return 

 to the forest condition and old, gnarled apple trees even, the rem- 

 nant of some forgotten orchard, may be foimd still living in the 

 midst of the woods and completely surrounded by forest trees. 

 These various stages of development may be pieced together and 

 may enable us to make out the order of "forest succession." 



The climate of a given locality is the resultant of such diverse 

 factors as latitude, altitude, rainfall and exposure to wind and 

 sun. It is expressed by the character of the vegetation. The length 

 of the growing season, from the gradual awakening of growth in 

 the spring till its cessation in the fall, is of prime importance to 

 agriculture. Are the springs and falls early or late in a given lo- 

 cality? The progress of the seasons can best l)e measured in terms 

 of tree activities, such as the appearance of the leaves and flowers, 

 the ripening of the fruit and the falling of the leaves in different 

 species. Observations of these points in the yearly history of dif- 

 ferent species of trees is of so much importance in measuring gen- 

 eral and local climate, that the Forest Service, Washington, D. C, 

 is attempting to obtain records on this subject from as many dif- 

 ferent places as possible. They will gladly send record blanks to 

 anyone willing to co-operate with them in making observations. 

 The time of opening of the bud, of flowering and of leaf fall if ac- 

 curately recorded, especially for a series of years, although for 

 only a single species, will be information of value. 



The life of the individual tree will well repay our study. What 

 are the problems that it must solve in order to lead a successful ex- 

 istence, and how are these problems solved by different kinds of 

 trees? These questions are discussed in Chapter II. The effect of 

 external conditions upon the habit is touched upon in Part II. 



Tree Measurement — The information regarding the dimensions 

 of a tree are of minor importance for purposes of identification, but 

 are of considerable value to the woodsman. The diameter of the 



