FACTORS OF FOREST PRODUCTION. 123 



with pasture and farm use, and which require care- 

 ful consideration as to which use is financially, or 

 for other reasons, preferable. 



If we compare the amount of production per 

 acre in the two industries, it must not be forgotten 

 that in such countries as Europe the forest occupies 

 already mostly these poorer sites and situations, 

 the absolute forest soils, and hence the comparison 

 must be unfavorable, apparently, as far as money 

 returns are concerned. 



In amount of vegetable material produced, for- 

 est crops, to be sure, are in no way inferior ; nay, 

 if we do not confine ourselves to the wood, but 

 add the leaf litter produced per year, offsetting 

 the straw of agricultural crops, the forest pro- 

 duces larger quantities in weight than the farm. 

 Taking average crops of the common farm prod- 

 uce, there are produced dry weights of 3400 to 

 4600 pounds vegetable substance per acre, of 

 which, mostly, not more than one-third is repre- 

 sented in the grain ; while the forest acre produces 

 8000 to 10,000 pounds, of which one-half or more 

 is wood, namely, 4500 to 6500 pounds, with 450 

 pounds for roots, and 3000 pounds for leaves, the 

 dry substance of wood grown per acre per year 

 varying between 1500 and 3600 pounds, accord- 

 ing to the site.^ The interesting fact is that all 

 species produce on the same site the same weights, 



1 A one-hundred-year-old stand then contains at best 180 tons 

 of dry wood, equivalent to about 90 tons of carbon. 



