36 
The diameter given for oak at seventy years is considerably 
larger than that given for European oak at the same age, or 
indeed for any other hardwood. The shortening of the rota- 
tions at present employed in the older countries is at present 
one of the most urgent problems in forest research. 
Both the ash and oak as given in the yield tables can be 
considered as standards for quality I. No better growth is 
found in this locality. The quality I sites are mainly at the 
lower elevations. The lower slopes are moister. The same 
quality soil at a higher and drier elevation must be regarded 
as quality II. Only two site qualities occur for oak and ash. 
Where the soil becomes too dry or too wet other species re- 
place these two trees. 
From Table XVIII it will be seen that the difference in 
height growth between oak and ash is very small, the greatest 
difference, four feet, occuring at the thirtieth year. There is 
less variation in the average annual height increment of ash, 
from decade to decade, than is the case with oak. The 
greatest individual height increment in oak saplings was 
found to be four feet three inches, and this occurred at the 
eleventh year. A growth of four feet one inch was also found 
in the ninth year. Ash does not appear to make any such 
growth as this. 
The lower limit of quality I as indicated by height is shown 
by the figures given in the following table. Heights below 
this must be regarded as indicating quality IT. 
TABLE XX 
Age in Height 
Years in Feet 
WO so sc tecessen ek eee cc secre Seer e fuk eas Bd ao Gbea cd dot ahdlerw es 14 
IDO) crete id isha rasaeabauls sam. abeien Saenteyteeca antni SMa ate gpecwes 34 
BO he cea ea ries yahoos tras hte re aerate as ote aetnn ores 50 
AO) 2 duel Sacivns tna rated sdreeivevte Reeke lapek enact Sayin aod 61 
DO idiarioverasanbeeeneantsd way tao enpean eats ctr heh he aya eo 69 
OO rieie ua tgdaten ears aus area each Deady ween oaeaeals ots 74 
