1902. 



FORESTRY AND IRRIGATION. 



415 



ern Jack Pine has several noteworthy 

 pecuHarities. Its firmly closed cones, 

 often surviving even a hard forest fire, 

 open so reluctantly that it has been as- 

 serted that fire was necessary for their 

 opening. How long the vitality of the 

 seed is retained in these cones has per- 

 haps never been fully determined, but 

 there is little doiibt that it continues for 

 a number of 3'ears. This peculiarity 

 and its advantages are well known, and 

 have been discussed so often that there 

 is danger of its being overrated. Nev- 

 ertheless, it appears certain that this 

 peculiarity of the Jack Pine, together 

 with its regularity and abundance of 

 seed production, are the chief qualities 

 which make the tree a regular "fire 

 pine." 



In its development the Jack Pine 

 must be counted among the rapid 

 growers, both in height and in diame- 

 ter. In keeping with its scrub-pine 

 character, however, this period of rapid 

 growth is short, and is followed, not 

 by a steady, moderate growth, but bj^ 

 a sudden and permanent decline in the 

 rate of growth, which appears to indi- 

 cate a short rotation for jack pine for- 

 ests. 



Unlike its common neighbor, the 

 Norway Pine, the Jack Pine, like others 

 of the scrub pines, departs in the for- 

 mation of its crown from the regular 

 form common among the pines. Its 

 limbs are not regularly set in whorls, 

 but extra limbs appear, inserted at ir- 

 regular points, and thus disturb the 



SCENE IN VIRGIN FOREST OF WHITE AND NORWAY PINE, MICHIGAN. 



