24 BULLETIN 523^ U. S. DEPARTMENT OF AGP-ICULTURE, 



medium sized trees. The silviciiltiiral conditions for growing such 

 trees are a good soil and abundant growing space. 



Sj^ecies. — Table 10 indicates that distinction between species is of 

 little importance in judging mechanical values. Thus while one lot 

 of white ash was the best of any tested, two other lots ranked below 

 one of green ash. 



With the exception of black ash, which will be considered later, 

 the differences in mechanical properties of the various species of ash 

 are the same as would be expected in trees of the same species with 

 varying specific gravities. In general, however, ash species growing 

 under natural conditions will rank about as follows in relative 

 strength as a beam or post: White ash, green ash, blue ash, Biltmore 

 ash, pumpkin ash, black ash. Pumpkin ash and black ash usually are 

 found growing jLinder unfavorable conditions (wet swamps and slow 

 growth ) for putting on dense wood ; while white, blue, and Biltmore 

 ash occur naturally on more favorable sites ; green ash occurs about 

 half on sites with defective drainage and half on sites where the 

 drainage is sufficient, but always on rich alluvial soil. (See Pis. VII, 

 VIII, and IX.) 



A further classification of the relative strength of the different 

 species, of importance to future growers of ash timber, may be made 

 on the basis of uniformly fast growing, small to medium sized trees, 

 growing under favorable conditions, such as would be secured under 

 proper management. From this standpoint the species probably 

 would rank as follows : White ash, green ash, Biltmore ash, blue ash, 

 and black ash. It would be hard to say whether pumpkin ash Avould 

 precede or follow blue ash, where grown under favorable conditions. 

 This ranking of species is based on Table 10, consideration being 

 given at the same time to rate of growth (rings per inch), age (or 

 size), character of site, and- the conditions given in Table 11. These 

 factors account for apparent variations in the relative strength of 

 the different species. Thus the blue ash in the table has a relatively 

 high rank because of the unusually favorable conditions for putting 

 on dense wood under which the specimen trees grew — all the trees 

 were predominant and grew in an open stand on limestone soil. It 

 will be seen, also, that the blue ash falls below gi-een ash of Missouri 

 in strength, although equalling it in weight and having fewer rings per 

 inch. Black ash, on the other hand, if grown under favorable condi- 

 tions, might reasonably be expected to produce much stronger timber 

 than the table indicates — nearly equal to blue ash, to which it is 

 botanically closely related. 



The tests on black ash in the green condition indicated almost 

 double as much moisture content as the tests on any of the other 

 ashes. Black ash is the lightest of the ashes tested, is very weak, 



