JACK PINE. 19 
persist on the tree for several years, opening gradually under the 
drying effect of heat and wind. Many cones that are on the ground 
do not open at all until scorched by fire. The process of seed dis- 
seminatioh of jack pine is thus almost continuous. 
The small, light, jack pine seed with its relatively large wing 1s 
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, carry 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 OF SEED. 
Freshly gathered samples of jack pine seed have shown germi- 
nating percentages of 95 or 100.2 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 produced 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. I 
ib 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 wnopen on the trees. 
2 State Forester Schaal, of Michigan, reports a 58 per cent germination for good, fresh seed. 
