PERIODICAL LITERATURE 



FOREST GEOGRAPHY AND DESCRIPTION 



The coniferous forests of Minnesota occur to 

 Distribution of the northeast of a line drawn from near the north- 

 Jack Pine western corner of the State in a southeasterly 



in direction to the boundary of Wisconsin at about 



Southeastern latitude 45° 30'. This line shows a marked con- 

 Minnesota vexity toward the southwest, amounting to about 



75 miles in its middle portion. Rosendahl and 

 Butters, in a recent article, state that the original distribution of the 

 three pines, Pinus strobus, P. resinosa, and P. banksiana, within the 

 coniferous forest area was determined largely by soil conditions. Of 

 these species the first is the one most capable of maintaining itself out- 

 side the evergreen forest area and of forming isolated outposts. These 

 outposts of white pine are numerous, and for the most part consist of 

 small groups of a few trees on rocky ledges of river bluffs, but occa- 

 sionally of pure groves of an acre or more in extent. The authors 

 state that to their knowledge there are about 30 of these isolated patches 

 of white pine in southeastern Minnesota today, some consisting of but 

 a few old trees, while others include younger trees and seedlings as 

 well. Although many of these isolated patches of white pine occur 50 

 or more miles from the border of the coniferous forest area, the red 

 pine and jack pine behave differently in their distribution. They rarely 

 appear as isolated groups beyond the general area. 



The red pine is not found beyond the general coniferous area except 

 in the valley of the St. Croix River, where it forms outposts on the 

 exposed Precambrian diabase of the river valley a few miles beyond 

 the general border of the evergreen forest area. 



Although the jack pine with the white pine form the skirmish line 

 along the evergreen forest area across the entire State, the known out- 

 posts of the former were confined to three stations, all less than 15 

 miles from the general coniferous border until 191 5, when a grove near 

 Rushford was located about 120 miles from its previously known limit 

 in Minnesota and some 50 miles southwest of the nearest place where 

 jack pine is known to occur in Wisconsin. This isolated grove is con- 

 fined to a limited area of disintegrating Paleozoic sandstone, so that the 

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