FOREST commissioner's REPORT. 83 



to develop more rapidly and eventually to establish themselves 

 as the permanent forest type. 



In mixture paper birch occurs in three quite distinct ways — 

 with aspen, with other hardwoods, and with conifers. Mixed 

 stands of brich and aspen closely resemble pure birch stands in 

 general character and appearance. The two species may be 

 present in practically equal numbers, or one or the other may 

 slightly predominate. There is the same even-aged, even- 

 crowned character of the pure birch stand, except that the aspen 

 often shows larger and taller individuals than the birch. The 

 stands begin to break up at about tlic same age and to deteri- 

 orate in much the same way. 



When paper birch is mixed with other hardwoods its prin- 

 cipal associates arc yellow birch, sugar maple, and beech. These 

 .stands differ considerably from pure birch stands. They are 

 often irregular and not even-aged, and evidently start as a more 

 or less open mixed stand in which paper birch is prominent. 

 Then more tolerant species gradually come in and fill up the 

 blanks, .so that the stand assumes somewhat the character of a 

 virgin forest with various age classes present. Paper birch in 

 such stands usually develops a spreading crown, a large diam- 

 eter, a knotty bole, and a comparatively short merchantable 

 length. The tree is likely, however, to have a large proportion 

 of clear, white sapwood and to remain .sound longer than when 

 in pure stand. Stands of this character, when the birch has 

 once been cut or has died out, usually revert to the mixed hard- 

 woods, type. 



Mixed stands of paper birch and C' >nifers, usually spruce and 

 balsam, have still a different character. In these the birch and 

 conifers usually take possession of the ground at the same time, 

 although the conifers may be a few years later in making their 

 appearance. The birch, however, makes a very much more 

 rapid height growth in early youth and soon overtops the coni- 

 fers, so that the stand has the appearance of a two-storied for- 

 est, the birch occupying the upper story, with plenty of space 

 and light in which to develop. The spruce and balsam are tol- 

 erant and thrive under the relatively light shade. Their growth 

 is more persistent and well-maintained than that of the birch, 

 and in time they overtake it. The exact age at which they do 

 this varies considerably, but as a rule the conifers catch up with 



