6 BULLETIN" 139, U. S. DEPARTMENT OF AGRICULTURE. 



years are local; there may be a good crop in Minnesota and a failure 

 in Michigan or Wisconsin the same season. According to Forest 

 Service records there have been five seed crops in Minnesota at 3- 

 year intervals since 1898. In Wisconsin there were crops in 1890, 

 1893, 1897, and 1900. In Canada good seed years are said to occur 

 not oftener than every 5 to 7 years, due possibly to the colder cli- 

 mate. Trees in the open have produced good cones when 25 years 

 old, and in stands when from 50 to 60 years old. It is not known 

 definitely when seed production begins to fail in old stands, but 

 probably the fertility and quantity begin to fall off when the trees 

 reach an age of 150 years. Squirrels annually destroy large quanti- 

 ties of seed. 



The seed is disseminated by the wind and can be relied upon to 

 restock areas at least 300 yards away, provided the soil has been 

 bared by logging. Even after proper dissemination there is always 

 a chance that seed will fall on heavy litter to dry out before germina- 

 tion or on sodded ground where it can not get a start. Seedlings 

 do not establish themselves after fire if there is much ash on the 

 ground. Light burning before a seed crop may often be conducive to 

 excellent reproduction where the soil is moderately rich. On dry, 

 pure sand even a light fire may keep out Norway and white pine and 

 give jack pine a start. After a fire jack pine always seeds before 

 Norway, because it produces seed each year, which are released from 

 cones by the heat of the fire. White pine will come in first where 

 there is partial shade, provided it is not crowded out by broadleaf 

 trees. On areas between these two extremes of baked, parched soil, 

 free from all growth on the one hand and ground covered with 

 dense underbrush on the other, Norway pine reproduction will have 

 the best chance. 



However, the three pines compete with one another for the occu- 

 pancy of the ground, as shown by actual measurements of repro- 

 duction on small plots in the National Forests. On the Minnesota 

 National Forest, on an area where 5 per cent of the stand had been 

 reserved for seed, there were 1 ,900 Norway and white pine seedlings per 

 acre which had come in on exposed mineral soil rather than near the 

 seed trees. In Hubbard County, Minn., on a plot 50 by 100 feet, 

 there are 499 jack pine seedlings and only 481 of Norway pine, although 

 there were two Norway pine seed trees and no jack pine within 300 

 feet. In a small, open stand, composed of 3 white pine and 70 Nor- 

 way pine, growing on sandy soil, there were 13 white pine seedlings 

 to every 1 of Norway pine. Near Mahtowa, Minn., young stands of 

 Norway pine 7 and 8 years old averaged 20,855 trees to the acre, and 

 near Barnum and Moose Lake stands about 23 years old averaged 

 4,699 trees to the acre. This shows that excellent reproduction of 

 Norway pine is possible, provided soil conditions during the seed 



