JACK PINE. 19 



persist on the tree for several years/ opening gradually under the 

 drying cH'ect of heat and wind. Many cones that are on the gi'ound 

 do not open at all until scorched by fire. The process of seed dis- 

 semination of jack pine is thus almost continuous. 



The small, light, jack pine seed with its relatively large wing is 

 readily disseminated to considerable distances. It is probable that 

 light winds, which are of frequent occurence in the range of jack 

 pine during the season of dissemination, cairy some of the seeds for 

 distances of a quarter of a mile or more; but most of the seeds un- 

 doubtedly fall within 100 yards of the parent tree. 



QUALITY OP SEED. 



Freshly gathered samples of jack pine seed have shown germi- 

 nating percentages of 95 or 100.- Samples from cones that had 

 remained closed for some time indicated a germination of from 60 to 

 75 per cent. Seed in well-closed cones may retain its germinating 

 capacity many years. The great quantity of seed jjroduced and 

 the high average percentage of germination explain to a degree the 

 widespread distribution of this hardy species and its rapid regenera- 

 tion on burned lands. 



ESTABLISHMENT OF SEEDLINGS. 



Under average natural conditions jack pine seed requires from 

 2 to 4 weeks for germination. Good seed, however, will germinate 

 in 8 days under very favorable conditions of heat and moisture. If 

 it is moist enough, the poorest sand will make a seed bed. After a 

 a few weeks development of the root system the seedling becomes 

 drought-resistant. 



Reproduction is most plentiful on bare soil in the open, where the 

 germinating seed strikes quickly into the mineral soil. Jack pine 

 reproduction is usually excluded by other trees, weeds, and under- 

 brush from better classes of seed bed, such as have a layer of well- 

 decomposed humus. But a fire that destroys these and bares the 

 mineral soil gives jack pine an excellent chance. In fact, fire is 

 usually a necessary precursor of very dense jack pine reproduction, 

 especially on good sites, because it clears the seed bed and opens up 

 old cones. Where jack pine seeds in after a fire it is usually able to 

 hold its own against other species. In northern Minnesota, how- 

 ever, if birch or aspen seed in simultaneously with it on a better 

 class of soil, they usually crowd it out. 



Jack pine seeding after a fire commonly produces an overstocked 

 stand. Such a stand when 6 feet high would have from 5,000 to 

 10,000 trees to the acre; but, on account of the intolerance of the 

 species, this number would rapidly diminish, so that the danger of 



1 In the southern part of the range of jack pine in Wisconsin very few cones remain imopen on (he trees. 

 » State Forester Schaaf, of MicMgan, reports a 58 per cent germination for good, fresh seed. 



