78 



TIMBER RESOURCES FOR AMERICAS FUTURE 



Stocking Deficiencies Most Significant 

 Element in Productivity 



Regardless of locality, ownership, or forest type, 

 substandard stocking proved to be the main factor 

 in lowering the index of forest productivity suffi- 

 ciently to cause recently cut lands to drop out of 

 the upper class. Deficiencies in existing stocking 

 were more pronounced in the South and West than 

 in the North, and in small private ownerships than 

 in large and medium private ownerships or in 

 public OAvnerships (table 51). For the Nation as 

 a whole, if existing stocking were the only criterion 

 of productivity, over half of the recently cut lands 

 would fail to qualify in the upper productivity class. 



Prospective stocking often partially offsets 

 deficiencies in existing stocking. On individual 

 ownerships, prospective stocking might offset lack 

 of existing stocking entirely, but this was not 

 general for any section of the country or for any 

 major ownership group. Prospective stocking 

 was most effective in the West and on the public 

 and large and medium size private ownerships. 

 It was least effective on the small private owner- 

 ships. Whereas over half of the recently cut areas 

 in the Nation failed to qualify for the upper pro- 

 ductivity class because of deficiencies in actual 

 stocking, a little more than half of this area was 

 returned to the upper class when allowance was 

 made for prospective stocking (table 51). When 

 both existing and prospective stocking were con- 

 sidered, about one-fourth of the recently cut lands 

 would still fail to qualify for the upper productivity 

 class. 



Reasons for nonstocking were recorded for parts 

 of the Pacific Northwest where certain additional 

 data were obtained. In that region, the most im- 

 portant reasons for nonstocking appeared to be 

 inhibiting vegetation — especially brush, presence 

 of cull or noncommercial species, or a perennial 

 sod cover — and inadequate seed source. Adverse 

 site conditions, rodents, or other animals were 

 judged to be of less importance. 



In all regions, species composition and felling 

 age had much less effect on forest condition than 

 either existing or prospective stocking. However, 

 composition and felling age were more important 

 in the North than elsewhere, and on small private 

 than on other ownerships. On a national basis, 

 deficiencies in species composition were responsible 

 for removing only 4 percent of the recently cut 

 lands from the upper productivity class, and 

 premature cutting had about the same effect. 



Species composition was appraised mth respect 

 to the proportion of desirable and acceptable spe- 

 cies that stocked the area after cutting. If com- 

 position of the stand after cutting had been con- 

 sidered in relation to that before cutting, it is 

 possible that composition would have been a more 

 significant element. In Douglas-fir types of the 

 Pacific Northwest, Douglas-fir tended to occupy 

 a smaller proportion of the stand after cutting 

 than before cutting. This was true of recent clear 

 cuttings in all ownerships except the national 

 forests where the proportion of Douglas-fir in- 

 creased. Similarly, in the ponderosa pine tj'^pes 

 in the Northwest, ponderosa pine tended to make 



Table 51. — Relative e^ect of various elements in deriving upper productivity percentages 



BY SECTION 





Proportion of operating area deducted ( — ) 

 or added ( + ) due to — 



Proportion 



of area 



in upper 



Section or class 



Existing 

 stocking 



Prospective 

 stocking 



Composi- 

 tion 



Felling 

 age 



productivity 



class on 



basis of all 



elements 



North. 



Pei'cent 

 -40 

 -62 

 -59 



Percent 



+ 23 

 + 27 

 + 37 



Percent 

 -8 

 -3 



-2 



Percent 

 -8 

 -7 

 -1 



Percent 



67 



South ___ . .. . . 



55 



West and Coastal Alaska _ . .. 



75 







All sections _ 



-55 



+ 29 



-4 



-5 



65 









BY OWNERSHIP CLASS 











Large and medium private 



Small private 







-49 

 -62 

 -52 



+ 30 

 + 19 

 + 35 



-4 

 -6 

 -2 



-4 

 -11 



-1 



73 

 40 



Public 



80 









All ownerships 



-55 



+ 29 



-4 



-5 



65 







