A GENERALIZED YIELD TABLE FOR EVEN-AGED, WELL- 

 STOCKED STANDS OF SOUTHERN UPLAND 

 HARDWOODS 



By W. D. Sterrett ^ 



Forest B.rainincr, U. S. Forest Service 



The importance and use of site classification work, based on age and 

 height, the principles of which were carefully regarded in the prepara- 

 tion of the generalized yield table to be discussed will first be sum- 

 marized. An outstanding feature in the future development of forest 

 mensuration in the United States, it seems to me, will be to tie up to 

 quality of site all growth and yield tables for a given species, both for 

 single trees and stands, and, to a less extent, form and volume tables, 

 using average height attained by dominant trees as an index for judg- 

 ing quality of site. Height has long been recognized and used in 

 Europe as the most practicable index for judging differences in yield 

 capacity of different land for a given species. Quality of site, as 

 indicated by height, is much more definite and precise as a factor for 

 indicating possible rate of growth and yield on different lands than the 

 much abused term "forest type." The latter often includes several 

 distinct qualities of site, and in other cases a given quality of site 

 might embrace several forest types. Physical types, on the other hand, 

 based chiefly on soil and physiography, which correspond to a given 

 quality of site as determined by height for a given species, are also 

 important for determination and description in site classification work 

 for a species. 



The first step in making growth tables for a given species should be 

 the construction of a series of age-height site curves based on sufficient 

 data to cover the range of sites on which it grows, the range in age 

 classes from young to mature, and sufficient to establish the proper 

 direction of the cur^'es for each site class. Growth tables for single 

 trees and stands should be made separately for the different age-height 

 site classes thus determined. In making age-height site curves it has 

 been found most convenient to make even intervals between the curves. 



The yield curves (see figure) were prepared by E. H. Frothinghar 

 382 



