Periodical Literature 117 



the dominant trees. Hence the well-known cylindrical form of 

 the lower tree classes. 



7. In older trees, which are liberated, a considerable change 

 in increment and form takes place. The ring width invariably 

 decreases upwards except, perhaps, in the middle portion, where 

 it may remain even, and especially toward the root collar the 

 ring width increases, the taper is accentuated. The same is ob- 

 served in trees that grow up in the open. These changes in 

 older trees are characteristic for the different species ; only the 

 spruce lacks somewhat in this respect. 



8. Due to the difference in the disposal of substance each species 

 shows a characteristically different form. Beech and fir are 

 columnar, cylindrical to the base of the crown, then in the fir 

 a parabolic top piece, in the beech a slender conical, and in later 

 age neiloid form follows. Pine develops its top similar to fir, 

 but in the lower trunk, especially below breast height, it is rapid- 

 ly tapering, hence its form factor is considerably lower than 

 that of fir. The spruce is slightly more tapering than the fir and 

 beech, but very much less so than the pine, except again in the 

 top pieces, hence its form factor lies between pine and fir. 



(We would conclude that Pressler's theory is still good in ex- 

 plaining in general the development of tree form with slight 

 changes which may be due to the dynamic needs accentuated by 

 Metzger and Jaccard. Rev.) 



Die Formausbildung der Baumstdmme. Oesterreichische Vierteljahrs- 

 schrift fiir Forstwesen, 1915, pp. 217-62. 



SOIL, WATER AND CLIMATE 



Five years of records near Flagstaff, 



Forest Arizona, indicate that the snowfall in the 



Influence forest and adjacent grass and farm land 



on park is the same ; but that the rate of melt- 



Snow ing is different. In the park the minimum 



temperatures are lower and the maxima 



are higher than those in the forest. Thus the soil in the park is 



generally frozen before the winter snow cover is established, 



while in the forest the soil may freeze only in a few spots. Any 



water from melting snow in winter forms an ice layer at the 



base of the snow cover in the park, but sinks into the ground in 



