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 Pinm 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 lifeexcept 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) 5 1 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 f have the 

 similar habit of producing cones at a very early -age. 



