46 BRITISH FOREST TREES 



Beech forest. 



Oak forest, ash forest, hornbeam forest. 

 Birch forest. 



The conifers in general are more energetic in growth of 

 cubic contents than the broad-leaved deciduous trees, and 

 Gayer estimates that on the average the vital energy of 

 crops of silver fir and spruce is about 100 per cent, and that 

 of pine about 50 per cent, greater than beech, which is 

 the broad-leaved species best endowed in this respect. 



5. Differences of forest trees as to reproductive power. -In 

 the vegetable as also in the animal world the effort made 

 in reproducing and increasing the species is under certain 

 circumstances even greater than that devoted to the main- 

 tenance of individual existence for the longest possible 

 period. The tendency to reproduction is seen in all forest 

 trees, as when treated in a natural manner they yield rich 

 supplies of seed at short intervals during a great portion of 

 their term of existence. 



The natural process of reproduction takes place either 

 from seed shed by the trees, or else by means of shoots 

 from the stool, or stoles or suckers from the roots. 



(a) Reproduction from seed is the chief method of propa- 

 gation, and that in which the various forms of high forest 

 are usually produced. The quantity of seed formed 

 depends on many factors, the principal of which are the 

 species of tree, the age of the trees, the nature of soil and 

 situation, and the amount of light enjoyed. 



The various species of trees show great differences in repro- 

 ductive capacity as measured by the total quantity of 

 germinable seed produced during a period of several decades ; 

 while again this total is dependent on the average quantity 

 of good seed produced in each seed-year, and on the 

 frequency with which seed-years recur. The monoecious 

 species (e.g. oak, beech, conifers), in which pollination 



