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FORESTRY BRANCH BULLETIN NO. 33 



meadows are the result of fire, and many are formed after a single fire in the manner 

 described. 



Reproduction of poplar follows fires, mainly on the edges of the meadows, which 

 are commonly bordered by this species. Poplar prefers a moist seed-bed, and, on 

 account of the rapid growth of its seedlings, can compete against grass. These stands 

 are seldom extensive. Poplar also seeds in with spruce on moist sites and is found as 

 a minor component of the stand. The largest areas of poplar are found on southern 

 exposures where its presence is due mainly to the ability of its seedlings to develop 

 on sod. 



REPEATED FIRES. 



When a fire occurs in a second-growth pine stand, if there has been an interval 

 of twenty-five or more years since the fire from which the second-growth stand 

 dates its origin, reproduction will usually be dense, as pine begins to bear cones at 



Photo T. W. Dwigh 

 Plate 8 Mixed Stands of Second-growth Aspen and Lodgepole Pine, Resulting from Repeated Fires. 



an early age. In a stand younger than twenty-five years, the reproduction may be 

 more or less scattered, and grass will occupy the remaining area. The grass will 

 assume the dominance, if the stand be too young to have an effective stock of seed, 

 or if the second fire is followed by still others^ The result is that the areas become 

 mainly grass-land, with scattered young trees. When repeated fires occur in young 

 stands in which aspen forms a part of the stand and in which the amount of seed on 

 the pines is limited, the aspen is at an advantage on account of its sprouting capacity. 

 Most of the aspen stands on drier sites owe their formation in part, at least, to this 

 factor. 



When a fire runs through reproduction under ten to fifteen years old, the occur- 

 rence of future tree-growth depends on the existence of a portion of the original 



