Forest Research Problems and Program— Taylor 15 



these soon fall. Pulp cutting, however, will be in the climax 

 forest with its many live culls which may be left standing. Re- 

 generation may be sparse as the result of shade and competition 

 and the new stands may contain more hemlock and be some- 

 what understocked. This is a major silvicultural problem. 



The Climax Forest 



This climax forest should be explained, perhaps. The rough 

 picture is this: 



When a stand of timber is blown down or clear-cut, an even- 

 aged young stand regenerates. When it becomes mature on the 

 better sites we may have a sawtimber stand. If uncut, the trees 

 become over-mature and gradually, one by one, they fall. The 



Table l.—An acre of climax forest and an acre of 80-year-old second-growth 

 compared.- Trees S inches in diameter, breast high and larger 



Climax Forest Second-Growth 



Age range— years 900 1 2 



Average diameter— inches 20 1 1.3 



Number of trees 102 364 



Net volume, cubic feet 4»343 8,922 



Annual growth, cubic feet 35 112 



stand gradually gives way to a mixture of ages as new trees, 

 mostly hemlock, come into the small openings. As there is little 

 light or space at any one time, growth is very slow. When the 

 original even-aged stand has vanished, we have the so-called 

 climax composed of trees ranging in age from a few years to 

 over 800 years, often on the same acre. The 800 year-old tree 

 may be only 18 inches in diameter. 



Nature works towards this climax (5). The forester prefers 

 the pre-climax of healthy young even-aged stands. They have 

 little disease or defect and produce on the average twice as 

 much volume in 80 years as the climax forest maintains (7). 

 See Table 1. Theoretically, the second crop, after pulp mills 

 cut the climax, would have so much more volume that the 



- Site 3 of climax forest compared to site index no of second growth. Climax 

 has 5 sites (6 logs to less than 1 log). Second-growth sites range from 70 feet to 

 150 feet at 100 years (7). 



