HERMAN H. CHAPMAN 33 



in height growth, but by its tough wood and resistance 

 to decay, it survives them. It is, therefore, more numer- 

 ous in old virgin forests than in those which have been 

 cut heavily and grown up to second growth since such 

 a condition favors the more rapidly growing oaks which 

 are shorter lived. 



Reproduction of Trees and Stands. The Seed. The 

 most important feature of the struggle of species, is the 

 ability of the trees to reproduce themselves, and the con- 

 ditions affecting reproduction determine the composition 

 of a stand. Seeds are borne by some species every year 

 abundantly. Such trees are always ready to seize an op- 

 portunity if offered. Others only produce seed at inter- 

 vals of two to seven years. Many conifers have this habit. 

 Spruce seed trees are five to seven years apart. The seed 

 borne in the intervening years is so small in quantity that 

 it is usually all destroyed by birds, animals or insects. 

 In seed years the abundance of the seed insures a sur- 

 plus over the ordinary ravages of such pests, and a crop 

 of seedlings, if conditions favor them. 



Distribution of Seed. In the distribution of seed, the 

 light wind blown seeds of the aspen will travel for miles. 

 As each seed is supported by a thistle-down tuft of hairs, 

 a few trees will seed up large areas. This is the chief ad- 

 vantage which such a species possesses. All conifers have 

 wind blown seeds, and the distance to which they will 

 blow depends on the lightness of the seed, the size of the 

 wing, and the position of the tree and strength of the wind. 

 Spruce seeds will travel half a mile down hill. But the 

 heavy seed of the longleaf pine will only fly to a distance 

 about equal to the height of the tree. Many hardwoods 

 as maples, elms and birches, have winged seeds, and can 

 capture seed spots at varying distances from the parent 

 tree. 



Of the trees which do not depend on the wind, some 

 produce berries or fruit, which is eaten by animals and 



