392 JOURNAL OF FORESTRY 



Alaska possibly can supply, above its own needs, a total of about 

 300.000,000 cubic feet of hemlock and spruce annually.* This amount 

 is relatively small and can cut little figure in the total needs. 



A number of years must elapse, naturally enough, before the cut 

 and burned over forest lands here figured can be brought into the pro- 

 ductiveness given above. 



This question is pertinent now : If entirely adequate measures of 

 forestry were introduced immediately on all the regions given, how soon 

 could the forest be built up to its full productive capacity? How soon 

 could this come even with the most energetic beginnings and with sus- 

 tained progress? The number of years, of course, must vary with the 

 seriousness of the retarding factors. For instance, to change an area 

 which is densely covered with undesirable sprout hardwoods, such as 

 have usually followed lumbering operations in the spruce forests of 

 New England, back to the more desirable spruce, is an exceedingly 

 difficult and lengthy task. To replant the sand plains of the Lake 

 States that have been so severely burned year after year that there is 

 now little or no tree growth on them is comparatively simple and easy, 

 and the years before these lands will be producing their full capacity 

 are numbered roughly by the rotation of the species grown. 



The figures given below are. to be sure, only estimates, but yet, per- 

 haps, pretty good estimates. They are based on silvical studies made 

 in most of the regions at one time or another by members of the faculty 

 of forestry at Michigan : 



TABI.E 2. 

 Region Years to become 



fully productive 



New England 12.5-150 



Middle Atlantic 125-150 



Lake States 100-125 



Central 50-100 



East Gulf and South Atlantic 50-75 



Lower Mississippi Valley 100-150 



Rocky Mountains 25-50 



Pacific Coast Probably could get onto sustained annunl yield immediately 



The above figures throw new light perhaps on the relative urgency 

 of adequate measures of forestry for the nation,' that is, measures 

 necessary to prevent further forest destruction. 



Forest devastation, as shown by the above, has now progressed to 

 such an extent in the countrv that it will take nearlv a hundred years 



* Obtained by this approximation : 10,000,000 acres at 30 cubic feet growth per 

 acre per year. 



