Table 1. - 



Average 10-year diameter growth rates by species 

 for trees growing on white pine land 



Species 



Average 10-year diameter 

 growth, all sites 



Standard deviation 

 of growth 





inCncS 



Inches 



Percent 



White pine 





1.023 



43 



Ponderosa pine 



O ITT 



.821 



38 



Grand fir 



2.131 



1.003 



47 



Douglas-fir 



1.755 



.921 



52 



Cedar-hemlock 



1.711 



.864 



50 



Western larch 



1.656 



.777 



47 



Spruce-alpine fir 



1.508 



.746 



49 



Lodgepole pine 



1.468 



.782 



53 



Source: Forest Sun/ey data. 



land. The vegetation cover on the white pine 

 land of the Northern Region has changed con- 

 siderably in this century as a result of man's 

 actions as well as natural factors. 



Forest management started in the white 

 pine area in the Northern Region about the 

 turn of the century, on land supporting largely 

 old-growth white pine timber. Since then the 

 Forest Service has been selling timber, gradu- 

 ally converting the unmanaged old-growth 

 forest to a regulated forest condition as 

 economic limitations would permit. During 

 this time a large volume of old-growth timber 

 was destroyed by wildfires, disease, and in- 

 sects. Today over half the forest area supports 

 stands of sawtimber-size trees. However, saw- 

 timber stands older than 100 years occupy 

 only a little over a third of the area. The 

 forest can be pictured in terms of stand size 

 as follows:^ 



Stand size 



Stand area 



^All resource data in the tabulation were obtained 

 from Forest Survey. All information except that pre- 

 sented later for young stands originating since 1949 

 is from surveys conducted in 1958-61. Tlie informa- 

 tion for the stands originating since 1949 was up- 

 dated by the Northern Region from recent stand 

 examination records and stand establishment records. 





(Thousand 



(Percent 





acres) 



of total) 



Sawtimber: 







Older than 160 years 



586 



18.2 



100 to 160 years old 



523 



16.3 



Less than 100 years old 



741 



23.0 



Subtotal 



1,850 



57.5 



Poletimber 



620 



19.2 



Seedling and sapling 



749 



23.3 



Subtotal 



3,219 



100.0 



Nonstocked 



278 





Total 



3,497 





Species composition of stands varies. Al- 

 though white pine is a component of many of 

 the stands on this land today, as a result of 

 type conversion only 12 percent of the 3.5 

 million acres of National Forest land capable 

 of growing white pine actually supports stands 

 in which white pine is the principal species. 

 Much of this is sawtimber that can be har- 

 vested; however, as the following tabulation 

 shows, there are 125,000 acres of white pine 

 type containing stands of trees that are below 

 sawtimber size: 



3 



