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PINE TREES OF ROCKY MOUNTAIN REGION. 45 
of its range, where formerly this pine was very abundant, the wood 
was but little used, except locally for fuel, light-traffic ties, and occa- 
sionally for rough lumber. In recent years, however, the scarcity and 
high cost of other northeastern pines has led to extensive commer- 
cial use of jack pine lumber wherever the trees are large enough to 
be milled. Logs as small as 6 inches in diameter are now cut into 
rough slack-cooperage stock and lumber for packing cases. Heavy 
“tongue-and-grooved” jack pine planking, used for roofing under a 
waterproof covering and for various other similar purposes, has been 
entering our northeastern markets more and more of recent years, 
but usually under an assumed name. The so-called “ Hudson Bay 
pine,” purporting to come from a far northern source, is in some 
instances jack pine. Clear grades of jack pine are so similar in 
appearance and working qualities to Norway pine that they could 
probably pass for Norway pine. For the most part, however, Jack 
pine produces a low-class knotty lumber unfit for the better uses to 
which Norway pine is put. 
OCCURRENCE AND HABITS. 
Jack pine is essentially a tree of barren sandy or rocky land 
throughout its wide range (Map No. 14). It occures also, however, 
in moist soils of good quality, which, if well drained, produce the 
largest trees. The vertical range of jack pine is between about 100 
and 1,200 feet above sea level. For the most part it forms either 
small scattered patches or extensive bodies of pure growth. In its 
eastern range Pinus banksiana is associated more or less with white 
pine, and to some extent also with Norway pine. The mingling of 
these species occurs chiefly when the jack pine begins to decline, the 
red and white pines later generally crowding it out. Jack pine is 
decidedly intolerant of shade at every period of its life except during 
the first year or two of seedling growth, when it bears light shade, 
but with some loss of vigor. 
Pinus banksiana is an abundant seeder, some seed being borne 
practically every year, but specially heavy seed production occurs 
at intervals of about 2 or 3 years. Trees in an open stand often begin 
to bear cones when they are only a few feet high (10 to 12 years 
old) ;+ trees in a dense stand begin to bear when about 25 years old. 
The seed has a very high rate of germination (from 60 to 80 per 
cent) and persistent vitality. Reproduction is usually scattered, 
owing doubtless to the irregular and tardy opening of the cones, 
but the precocious seed bearing results in gradual and constant ex- 
tensions and the filling out of openings in thin stands of this tree. 
1 Near relatives of the jack pine, Pinus contorta, P. virginiana, and P. clausa, have the 
‘simildr habit of producing cones at a very early age, 
