10 JOURNAL OF FORESTRY 



need not be determined if their diameters make it certain that they 

 have reached an age at which height growth is no longer active. Height 

 growth "maturity" is likely to have been reached in trees older than 

 150 years, so that the heights opposite this age in the table may be 

 regarded as applying to timber mature as to height growth. The 

 heights of the "mature" trees measured should be averaged, and the 

 site found by comparison with the average. This determination should 

 then be checked by measuring the age and height of the dominant 

 second growth of intolerant, rapid-growing hardwoods of the different 

 species which are to be found in the immediate vicinity. Scarlet, red, 

 and black oaks, poplar, and chestnut are suitable species for this 

 purpose. The immature trees chosen for measurement should give 

 evidence of having always been dominant; experience in this study 

 has shown that such trees can usually be found. 



Discrepancies between the sites indicated by miniature and "mature" 

 trees are to be looked for, especially when the six-class system is used. 

 It should be remembered that the juvenile stage is not always a 

 reliable index, as evidenced by the cases previously cited, and it should 

 be checked by measurements of "mature" dominants, where these can 

 be found on the site in question. As a rule, however, even the younger 

 dominants, when the heights for a given age class are averaged, 

 afford a satisfactory key to the site as it has been during their life 

 periods. They do not, of course, tell what the site may become as a 

 result of long continued protection from fire, and yield forecasts based 

 upon them ought to be conservative for sites which have been badly 

 burned. 



While the use of isolated trees as indices of site is still questionable 

 pending further study, it is not believed to involve a large risk. In 

 the case of old-growth timber, trees now isolated probably reached their 

 age of height growth "maturity" while still closely surrounded by other 

 trees, since logging operations in this region rarely date back over 

 three decades. The average height of such trees is without doubt close 

 enough to the average height of the upper crown cover of the original 

 forest to serve as a sufficiently reliable index. The second growth 

 measured in such stands, however, must not only not be advance growth, 

 which may have been suppressed at the start, but should be selected, 

 if possible, from groups representing substantially well stocked condi- 

 tions. It is believed, however, that a comparison of the height growth 

 of dominant second-growth hardwoods of intolerant species in relatively 

 open as compared with closed stands will not show a very great dif- 



