CONTENTS. 



Page. 



Introduction 3 



Historical 4 



Distinguishino; characteristics 5 



Silvical forms 7 



Variations between the coast and mountain forms 7 



Geographical distribution 11 



Relation of altitude to distribution 11 



Relation of exposure to distribution 12 



Silvical regions within the range of Douglas fir 13 



North coast region ^ 14 



Sierra region 15 



Northern Rocky Mountain region 15 



Central Rocky Mountain region 17 



Southern Rocky Mountain region 18 



Permanence of Douglas fir stands 19 



Silvical characteristics and requirements of the two forms 19 



Soil and moisture 19 



Tolerance 21 



Reproduction 22 



Susceptibility to injury 25 



Fire , 25 



Wind 26 



Frost 26 



Longevity 28 



Size 28 



Rate of growth 29 



Management 31 



North coast region 31 



Sierra region 34 



Northern Rocky Mountain region 34 



Central Rocky Mountain region 35 



Southern Rocky Mountain region 36 



Conclusions „ 37 



LLUSTRATIONS. 



Fig. 1. Specimens of Rocky Mountain and coast forms of Douglas fir 8 



2. Cones of the Rocky Mountain and coast forms of Douglas fir . 10 



3. Map showing distribution and silvical regions of Douglas fir 13 



[Cir. 150] 



(2) 



