2 BULLETIN 820, U. s. DEPARTMENT OF AGRICULTURE. 



and prolong the tenure of jack pine over extensive areas of sandy 

 ridges and plains. There are large areas with poor soil and severe 

 climate, especially in Canada, on which jack pine is the permanent 

 forest growth. It is, therefore, one of the characteristic forest types 

 of the North.i 



In the Lake States j ack pine produces chiefly smaU-sized, knotty 

 lumber, much inferior to that from the Norway and white pines which 

 grow with it. It has, however, good possibilities of profitable utiliza- 

 tion for pulpwood, box boards, mine timbers, and other low-grade 

 material. Its rapid growth when young, its good yields per acre on 

 poor land, and the ease which it reproduces itself make it suitable 

 for timber growing on a short rotation. 



Jack pine is an important tree for forest management on poor, sandy 

 soils in the region of its natural distribution, and has been successfully 

 planted outside of its natural range in the sand hills of western Ne- 

 braska. In the Lake States there are hundreds of thousands of acres 

 of poor, sandy plains-land, impoverished by fires, on which jack 

 pine is a pioneer tree, forming stands by natural reproduction where 

 white and Norway pine have not appeared. These two species come 

 in later with improved soil conditions and under the shelter of the 

 j ack pine. Wherever good stands of j ack pine can be secured without 

 expense by natural reproduction, that is usually preferable to plant-- 

 ing the land with more valuable species at considerable expense and 

 with less certainty of success. 



DISTINGUISHING CHARACTERISTICS. 



Jack pine has leaves in bundles of two, from | to If inches long, flat, 

 or slightly concave on their inner surface, and surrounded by a short 

 sheath. The cones are from IJ to 2 inches long, oblique at the base, 

 sessile, erect, and strongly incurved, with thick, soft scales, armed with 

 minute, incurved prickles which usually fall away. (See Pis. I and II.) 



The only other two-leaved pine with which jack pine is likely to be 

 confused is the lodgepole (Pinus contorta). The ranges of these two 

 species overlap slightly in central western Alberta.- Their leaves are 

 about the same size, and their cones are very similar. The cones of both 

 are curved, but those of jack pine are erect or pointing in the direction 

 of the end of the twig, while those of lodgepole are horizontal or declin- 

 ing, pointing upward or even backward. Jack pine is further dis- 



1 The growth, yield, form, and volume tables which are the chief basis for this bulletta were compiled 

 mostly from measurements taken in 1905 on pure, dense, even-aged stands of jack pine in Hubbard 

 County, Minn., by Prof. H. H. Chapman, of the Yale Forest School. The bibliography of data used and 

 reports consulted in the preparation of this bulletin is found on page 34 (appendix). 



2 "The lodgepole is ordinarily confined to higher elevations in Alberta. The upper portions of river 

 slopes will be occupied by lodgepole pine, while the lower slopes and bottom lands may be covered with pure 

 jack pine. As the river is followed into the hills the lodgepole pine gradually replaces the jack pine on the 

 lower levels and finally occupies the whole river bottom and side slopes. " — Extract from a letter by R. H„ 

 Campbell, Director of the Canadian Forestry Branch. 



