SAMPLE PLOTS IN" SILVICULTURAL RESEARCH 



77 



distinct, except in the lower crown. Branches are horizontal or upward curving, 

 except at the base of the crown where suppression is taking place. Numerous 

 stubs of dead branches are likely to be present below the crown. 



Class 2: Age class, young or thrifty mature; position, usually codominant 

 (rarely isolated or dominant) ; crown length, less than 65 percent of the total 

 height ; crown width, average or narrower ; form of top, pointed ; vigor, good 

 or moderate. 



Such trees are usually less than 24 inches in diameter. They are commonly 

 the inside codominant trees of groups. The crowns are smaller and less dense 

 than in trees of the first type. Otherwise they are similar to those of class 1. 



Class 3: Age class, mature; position, isolated or dominant (rarely co- 

 dominant) ; crown length, 65 percent or more of total height; crown width, 

 average or wider ; form of top, round ; vigor, moderate. 



These trees are ordinarily between 18 and 40 inches in diameter, depending 

 on site quality. The bark is light brown or yellow, with moderately large 

 smooth plates. The foliage is less dense than in class 1 trees. The top is 



to f^y., 



'Mi', ufc Jgfe 



Figure 4. — Tree classes in uneven-aged stands of ponderosa pine, as defined by Dunning. 



round, because of slow height growth. The nodes are indistinct, because of 

 incomplete whorls of branches. The branches are nearly all horizontal or 

 drooping. 



Class 4: Age class, mature; position, usually codominant (rarely isolated or 

 dominant); crown length, less than 65 percent of the total height; crown 

 width, average or narrower; form of top, round; vigor, moderate or poor. 



These are commonly the inside or codominant trees of this age class. Except 

 for their small, poorly developed crowns and smaller size, they are similar 

 to class 3 trees. 



Class 5 : Age class, overmature ; position, isolated or dominant ( rarely co- 

 dominant) ; crown of any size; form of top, flat; vigor, poor. 



These are usually the largest trees in the stand. The bark is light yellow in 

 color, the plates often very wide, long, and smooth, especially near the base. 

 The bark may be thin, having weathered more rapidly than it has grown. The 

 foliage is usually rather pale green and very thin. The needles are fairly 

 short, appearing as tufts on the ends of the twigs. The needles of 2 or 3 

 seasons only may be retained, even near the top. The top is flat, the terminal 

 rarely discernible. There is no appreciable elongation of the main axis. 



